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DEPARTMENT OF TRANSPORTATION may view this service information at the potential for a single erroneously high FAA, Airworthiness Products Section, AOA sensor input received by the flight Federal Aviation Administration Operational Safety Branch, 2200 South control system to result in repeated 216th St., Des Moines, WA. For airplane nose-down trim of the 14 CFR Part 39 information on the availability of this horizontal stabilizer. To address this [Docket No. FAA–2020–0686; Product material at the FAA, call 206–231–3195. unsafe condition, the NPRM proposed Identifier 2019–NM–035–AD; Amendment It is also available on the internet at to require installing new FCC software, 39–21332; AD 2020–24–02] https://www.regulations.gov by revising the existing AFM to remove the searching for and locating Docket No. AFM revisions required by AD 2018– RIN 2120–AA64 FAA–2020–0686. 23–51 and to incorporate new and revised AFM flightcrew procedures, Airworthiness Directives; The Boeing Examining the AD Docket Company Airplanes installing new MDS software, changing You may examine the AD docket on the horizontal stabilizer trim wire AGENCY: Federal Aviation the internet at https:// routing installations, completing an Administration (FAA), DOT. www.regulations.govby searching for AOA sensor system test, and performing ACTION: Final rule. and locating Docket No. FAA–2020– an operational readiness flight. The 0686; or in person at Docket Operations NPRM also proposed to allow operation SUMMARY: The FAA is superseding between 9 a.m. and 5 p.m., Monday (dispatch) of an airplane with certain Airworthiness Directive (AD) 2018–23– through Friday, except Federal holidays. inoperative systems only if certain more 51, which applied to all The Boeing The AD docket contains this final rule, restrictive provisions are incorporated Company Model 737–8 and 737–9 (737 any comments received, and other into the operator’s existing FAA- MAX) airplanes. AD 2018–23–51 information. The address for Docket approved MEL. required revising certificate limitations Operations is U.S. Department of and operating procedures of the Transportation, Docket Operations, M– Related Actions Airplane Flight Manual (AFM) to 30, West Building Ground Floor, Room During September 2020, the FAA provide the flightcrew with runaway W12–140, 1200 New Jersey Avenue SE, conducted an operational evaluation of horizontal stabilizer trim procedures to Washington, DC 20590. the operating procedures (checklists) in follow under certain conditions. This FOR FURTHER INFORMATION CONTACT: Ian the proposed AD, to assess their AD requires installing new flight control Won, Manager, Seattle ACO Branch, effectiveness. The FAA also evaluated computer (FCC) software, revising the FAA, 2200 South 216th St., Des Moines, pilot training proposed by Boeing existing AFM to incorporate new and WA 98198; phone and fax: 206–231– pertaining to the 737 MAX. The FAA revised flightcrew procedures, installing 3500; email: 9-FAA-SACO-AD-Inquiry@ conducted the evaluation jointly with new MAX display system (MDS) faa.gov. the Ageˆncia Nacional de Aviac¸a˜o Civil software, changing the horizontal SUPPLEMENTARY INFORMATION: (ANAC) Brazil, Transport Canada Civil stabilizer trim wire routing installations, Aviation (TCCA), and the European completing an angle of attack (AOA) Discussion Union Aviation Safety Agency (EASA). sensor system test, and performing an Summary of NPRM This joint evaluation is referred to as the operational readiness flight. This AD Joint Operational Evaluation Board The FAA issued a notice of proposed (JOEB). The operational evaluation also applies to a narrower set of rulemaking (NPRM) to amend 14 CFR airplanes than the superseded AD, and included airline pilots with varied part 39 and supersede AD 2018–23–51, levels of experience from the United only allows operation (dispatch) of an Amendment 39–19512 (83 FR 62697, airplane with certain inoperative States, Canada, Brazil, and the European December 6, 2018; corrected December Union. The FAA and the other civil systems if specific, more restrictive, 11, 2018 (83 FR 63561)) (AD 2018–23– provisions are incorporated into the aviation authorities (CAAs) concluded 51). AD 2018–23–51 applied to all that air carrier pilots operating the 737 operator’s existing FAA-approved Boeing Model 737–8 and 737–9 (737 minimum equipment list (MEL). This MAX need to complete special training MAX) airplanes. The NPRM proposed to on the 737 MAX, including ground and AD was prompted by the potential for apply only to the 737 MAX airplanes a single erroneously high AOA sensor flight training in a full flight simulator identified in Boeing Special Attention (FFS). The FAA also identified input received by the flight control Service Bulletin 737–31–1860, dated system to result in repeated airplane additional special emphasis areas to be June 12, 2020, which identifies line included in 737 MAX recurrent or nose-down trim of the horizontal numbers for airplanes with an original stabilizer. The FAA is issuing this AD continuing qualification pilot training. airworthiness certificate or original The FAA documented the results of to address the unsafe condition on these export certificate of airworthiness products. the JOEB evaluation in the draft FAA issued on or before the effective date of Flight Standardization Board (FSB) DATES: This AD is effective November the original Emergency Order of 20, 2020. Report, The Boeing Company 737, Prohibition. Airplanes that have not Revision 17 (draft 737 FSB Report). As The Director of the Federal Register received an original airworthiness approved the incorporation by reference described in an addendum to the draft certificate or original export certificate 737 FSB Report, the JOEB evaluation of a certain publications listed in this of airworthiness on or before the date of AD as of November 20, 2020. identified three areas in the proposed the original Emergency Order of Airspeed Unreliable checklist for ADDRESSES: For service information Prohibition will have been modified to potential refinement.1 On October 6, identified in this final rule, contact incorporate the changes required by this 2020, the FAA made the draft 737 FSB Boeing Commercial Airplanes, AD prior to receiving an original, or Report and the Addendum available to Attention: Contractual & Data Services original export, airworthiness the public for comment (85 FR 63641, (C&DS), 2600 Westminster Blvd., MC certificate. 110–SK57, Seal Beach, CA 90740–5600; The NPRM published in the Federal 1 These areas are described in the 737 FSB Report telephone 562–797–1717; internet Register on August 6, 2020 (85 FR Addendum, which is in the docket for this https://www.myboeingfleet.com. You 47698). The NPRM was prompted by the rulemaking.

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October 8, 2020). The comment period this final rule. This final rule mandates software; as a result, certain stickers closed November 2, 2020. corrective action that addresses an (known as INOP markers) will be The FAA issued the final FSB Report, unsafe condition on the 737 MAX. This removed. The Boeing Company 737, Revision 17, unsafe condition is the potential for a Additionally, this AD mandates dated November 16, 2020 (final 737 FSB single erroneously high AOA sensor adequately separating certain airplane Report), after considering the relevant input received by the flight control wiring, and conducting an AOA sensor comments received to the 737 FSB system to result in repeated airplane system test and an operational readiness Report docket (Docket No. FAA–2020– nose-down trim of the horizontal flight on each airplane before the 0928). The FAA considered the stabilizer, which, in combination with airplane is reintroduced to service. conclusions of the JOEB, comments multiple flight deck effects, could affect Finally, this AD requires that received during the NPRM comment the flightcrew’s ability to accomplish operators that wish to dispatch period regarding the AFM procedures, continued safe flight and landing. airplanes with certain inoperative and comments received during the draft As proposed in the NPRM, the systems must first have incorporated 737 FSB Report comment period in corrective actions mandated by this AD specific provisions that are more determining the final AFM procedures include a revision of the airplane’s flight restrictive into their existing FAA- contained in this final rule. For control laws (software).4 The new flight approved MEL. information on the refinements to AFM control laws now require inputs from Differences From the NPRM procedures identified in the proposed both AOA sensors in order to activate AD, please refer to the section of this MCAS. They also compare the inputs This final rule differs from the NPRM preamble titled, ‘‘Suggestions for Crew from the two sensors, and if those in minor respects. After review of input Procedure Changes.’’ inputs differ significantly (greater than from the operational evaluations and Additionally, the FAA has also 5.5 degrees for a specified period of public comments, the FAA adjusted two finalized the ‘‘Preliminary Summary of time), will disable the Speed Trim AFM procedures: The Airspeed the FAA’s Review of the Boeing 737 System (STS), which includes MCAS, Unreliable and the ALT Disagree non- MAX,’’ dated August 3, 2020, which the for the remainder of the flight and normal checklists. This AD simplifies FAA placed in the docket at the time of provide a corresponding indication of and corrects grammatical and publication of the NPRM. This that deactivation on the flight deck. The typographical errors in the Airspeed ‘‘Summary of the FAA’s Review of the new flight control laws now permit only Unreliable non-normal checklist (figure Boeing 737 MAX,’’ dated November 18, one activation of MCAS per sensed 2 to paragraph (h)(3) of this AD), and 2020, is also included in the docket for high-AOA event, and limit the revises the ALT Disagree non-normal this rulemaking. The final Summary magnitude of any MCAS command to checklist (figure 8 to paragraph (h)(9) of includes additional explanation move the horizontal stabilizer such that this AD) to correct a typographical error regarding 737 MAX design changes, the resulting position of the stabilizer in the NPRM. certification efforts, maintenance will preserve the flightcrew’s ability to The FAA has reviewed and approved considerations, pilot training, and final control the airplane’s pitch by using new and updated service information disposition of the Technical Advisory only the control column. This means the that is mandated by this AD, including Board (TAB) findings. The TAB is an pilot will have sufficient control Boeing Alert Requirements Bulletin independent team of experts that authority without the need to make 737–22A1342 RB and Alert Service evaluated efforts by the FAA and efforts electric or manual stabilizer trim inputs. Bulletin 737–22A1342, both dated by Boeing associated with the redesign The new flight control laws also include November 17, 2020, for the new FAA- of the maneuvering characteristics FCC integrity monitoring of each FCC’s approved FCC software; Boeing Special augmentation system (MCAS). The performance and cross-FCC monitoring, Attention Service Bulletin 737–31– conclusions from the TAB and which detects and stops erroneous FCC- 1860, Revision 1, dated July 2, 2020, for resolution of the findings directly generated stabilizer trim commands the MDS software change; and Boeing informed the FAA’s decision-making on Special Attention Service Bulletin 737– 2 (including MCAS). MCAS. The TAB included FAA This AD further mandates changes to 27–1318, Revision 2, dated November certification specialists and chief the airplane’s AFM to add and revise 10, 2020, for the horizontal stabilizer scientific and technical advisors not flightcrew procedures to facilitate the wiring change. This AD also provides involved in the original 737 MAX crew’s ability to recognize and respond credit for accomplishment of certain certification program. TAB members to undesired horizontal stabilizer prior actions as specified in paragraph also included subject matter experts movement and the effects of a potential (o) of this AD. from the U.S. Air Force, the Volpe AOA sensor failure. Public Comment National Transportation Systems Center, This AD also mandates an AOA and the National Aeronautics and Space DISAGREE alert, which indicates The FAA provided the public with an Administration. All findings that the certain AOA sensor failures or a opportunity to comment on the TAB members identified as required for significant calibration issue. The alert is proposed AD and received return to service of the 737 MAX were implemented by revision of MDS approximately 230 submissions to resolved to their satisfaction. Docket No. FAA–2020–0686. The FAA received comments from individual Summary of Final Rule 4 In the NPRM, the FAA used several terms (including ‘‘new,’’ ‘‘updated,’’ and ‘‘revised’’) when commenters as well as from After careful consideration of the describing the FCC software (including MCAS and organizations. The majority of the comments submitted 3 and further control laws) required by paragraph (g) of this AD. comments were from individuals. review of the proposal, the FAA adopts This software change is a complete replacement of the original FCC software, including a new part Organizations submitting comments number. This final rule requires installation of the included the Families of Ethiopian 2 The TAB Report has been included in this same FCC software as described in the NPRM and Airlines Flight 302; the civil aviation docket. refers to it as the new FCC software, new MCAS, authorities of Turkey (Turkish DGCA) 3 In developing this final rule, the FAA and new control laws. For example, where this final and the United Arab Emirates (UAE considered comments submitted to the NPRM rule uses the term ‘‘new MCAS,’’ this term reflects docket and also comments submitted to the 737 the same meaning as ‘‘revised MCAS’’ or ‘‘updated GCAA); the National Transportation FSB Report docket. MCAS’’ used in the NPRM. Safety Board (NTSB); the National Air

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Traffic Controllers Association concerns with the basic design and failure combination not shown to be (NATCA); Flyers Rights; Aerospace availability of MCAS. More specifically, extremely improbable (14 CFR 25.1309). Safety and Security, Inc.; the Aerospace these comments focused on the For example, a twin-engine transport Safety Research Institute, Inc.; Boeing; availability of MCAS after failure, airplane complies with all regulations Airlines for America (A4A); the whether the airplane remained safe and while both engines are operating, but if Ethiopian Airlines Group; the Joint compliant, and on the redundancy of there is a single engine failure, the European Max Operators Group the system and its inputs. airplane must be capable of continued (JEMOG); the British Airline Pilots FAA response: The FAA determined safe flight and landing with only the one Association (BALPA); the Allied Pilots that the 737 MAX with the new MCAS remaining engine operating. Association; the Association of Flight implemented by the new FCC software, With MCAS inoperative, the Boeing Attendants-CWA (AFA–CWA); Air as proposed in the NPRM and required 737 MAX is capable of continued safe China; Ameco; Travelers United, Inc.; by paragraph (g) of this AD, meets FAA flight and landing and is therefore Southwest Airlines Pilot Association safety standards. compliant with 14 CFR 25.671 and (SWAPA); and the Air Line Pilots The MCAS on the 737 MAX improves 25.1309. If at high AOAs, with MCAS Association, International (ALPA). the pilot handling qualities inoperative, MCAS will not move the The following summarizes the (maneuvering characteristics) during stabilizer, and the resultant incremental comments received on the NPRM, and non-normal flight conditions, change in column force will not be provides the FAA’s responses. specifically when the airplane is at high experienced by the pilot. In this AOAs. During normal flight, the 737 situation, the pilot maintains control A. Support for the NPRM MAX should never be at an AOA high and can decrease the airplane’s AOA by The FAA received supportive enough to be within the range that moving the column forward. Through comments on the NPRM from Travelers MCAS would activate. FAA regulations comprehensive analysis, simulation United, Inc., and numerous other require that airplanes be designed and testing, and flight testing, the FAA commenters. Commenters who tested over the entire range of potential determined that the airplane meets expressed support for the NPRM noted angles of attack, including high AOAs. applicable 14 CFR part 25 standards, the benefits of the proposed design FAA regulations also require column with MCAS operative and with failures, changes based on lessons learned and force to increase as AOA increases (14 including failures that render MCAS applied by the FAA, the resolution of CFR 25.143(g), 25.251(e), and 25.255). inoperative. With MCAS inoperative issues related to the airplane’s MCAS, In a 737 MAX, if a pilot is after a failure, the 737 MAX is capable the relative ease of accomplishing the maneuvering the airplane with the flaps of continued safe flight and landing, as proposed changes, a general retracted and encounters a high AOA required by 14 CFR 25.671 and 25.1309. appreciation for the airplane design and (outside of the normal flight envelope), If a system must be functional at all handling, and the length and intensity MCAS will activate and command the times to ensure continued safe flight of the review of the unsafe condition, stabilizer to move in the airplane nose- and landing, the system must be corrective action, and the airplane, down direction, which changes the available to function after a single which the commenters said resulted in handling characteristics such that the failure. Conversely, if an inoperative a safe design. The NTSB expressed pilot would need to pull with increasing system does not prevent continued safe general support for the NPRM as it force on the control column to maintain flight and landing, then it is acceptable relates to MCAS, noting ‘‘positive the current AOA or further increase the under FAA regulations for the system to progress on meeting the intent of the AOA. MCAS-commanded stabilizer not be available after a single failure; overall recommendation regarding movement results in increased column this is how MCAS is implemented on system safety assessments (SSAs) for the forces such that the airplane meets FAA the 737 MAX. Boeing 737 MAX relating to handling characteristics requirements The foregoing discussion focuses on uncommanded flight control inputs.’’ for airplane operation at high AOAs. an inoperative MCAS. All failure modes Existing FAA regulations (14 CFR 25.21, must be considered and assessed by the B. Fundamental Design/Approach 25.671, and 25.672) allow for use of manufacturer and the FAA for Concerns stability augmentation systems (such as compliance with 14 CFR 25.671 and The Boeing 737 MAX uses MCAS to MCAS) in showing compliance with 25.1309. The new MCAS is designed change the handling characteristics for FAA handling characteristics such that most failures will result in the the flightcrew in order to comply with requirements. The 737 MAX airplane MCAS function becoming inoperative, certain regulations during high-AOA with MCAS operative is therefore with maintenance required before a maneuvers. In the NPRM, the FAA compliant. subsequent flight to return MCAS to proposed to require the installation of To be approved by the FAA, the being fully operative and available. The new FCC software with new MCAS proposed designs of transport category manufacturer and the FAA have control laws to replace the earlier FCC airplane flight control systems must assessed potential failure modes of the software installed on 737 MAX comply with applicable 14 CFR part 25 system to ensure that no single failure airplanes. Several commenters regulations. The assessment of will prevent continued safe flight and questioned the fundamental design of compliance must consider the airplane landing and that any combination of the airplane, especially the inclusion in the as-designed, fully operational failures that could occur in service, and availability of MCAS. configuration (no failures) and also, in except for those shown to be extremely accordance with 14 CFR 25.671 and improbable, would similarly not prevent Comments Regarding Inclusion and 25.1309, in potential failure conditions. continued safe flight and landing. Availability of MCAS When assessing those failure conditions, Failures of MCAS are annunciated to Comment summary: Several the applicant must take into account the flightcrew. MCAS is implemented as commenters stated that MCAS should both the probability of the failures and part of the airplane’s STS. During flight, not be retained as a function on the their airplane-level consequences. The STS failures (including MCAS failures) airplane, and other commenters outcome must show that the airplane is are annunciated by illumination of the including the Families of Ethiopian capable of continued safe flight and master caution light, the SPEED TRIM Airlines Flight 302 had fundamental landing after single failures and any FAIL light, and the system annunciator

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panel (FLT CONT). Per training, the FAA response: As explained earlier in require that MCAS not activate if there flightcrew will follow applicable crew this preamble, the 737 MAX is capable is a disagreement between AOA sensor procedures for continued safe flight and of continued safe flight and landing inputs or a dual AOA sensor failure, and landing. with MCAS inoperative. Accordingly, that MCAS should not remain available Based on analyses, simulation, and continued safe flight and landing can be following certain AOA sensor failures. flight testing to establish consequences accomplished when MCAS is disabled FAA response: The FAA confirms that of failures and the capability for following the failure of a single AOA most AOA sensor failures will result in continued safe flight and landing, the input. The new MCAS, as proposed in the MCAS function becoming FAA has determined that the new the NPRM and mandated by this AD, inoperative, and if MCAS is activated, it MCAS meets FAA safety standards, and utilizes two AOA inputs and compares will activate only once for each high- that it is acceptable for STS (including the difference between them. If there is AOA event, which does not preclude MCAS) to remain inoperative for the a significant difference (greater than 5.5 continued safe flight and landing. AOA remainder of a flight after the system degrees for a specified period of time), sensor failures can be divided into two fails. Therefore, the additional then MCAS will be disabled broad categories: (1) Detected failures of redundancy requested by commenters, (unavailable) for the remainder of that the electrical circuit that measures the angular position of the AOA sensor such to increase the availability of the flight, annunciation will alert the that the AOA data is labeled as invalid system, is not required. flightcrew to the failure, and maintenance will be required before and not used by user systems (including C. Specific Concerns About MCAS subsequent flight. MCAS); and (2) undetected failures that Regarding exposure to the elements do not damage the electrical circuit such 1. Comments Regarding Redundancy of (that is, weather conditions but not a that AOA data is transmitted from the Two AOA Sensors bird strike), AOA sensors are designed, ADIRU to the FCC as valid. Both 737 Comment summary: The Families of tested, and qualified for their MAX accidents involved the second Ethiopian Airlines Flight 302 asked operational environment as part of category of AOA sensor failures; the whether the two AOA sensor inputs to certification (14 CFR 25.1301). The new AOA sensor electrical circuit was MCAS are truly redundant. MCAS design accounts for safe unaffected and therefore perceived by FAA response: The two AOA sensors operation after AOA sensor failures due the ADIRU to be valid, and the and the data they provide are to environmental causes including bird transmitted value was used by the independent, and are therefore strikes that bend or break the vane of the MCAS function in the FCC. With the new MCAS, the second type redundant in that the failure of one AOA sensor, as discussed in subsequent of AOA sensor failure will result in AOA sensor does not impede the responses. disparate inputs to the FCCs. When operation of the other AOA sensor. For 3. Comments Regarding Keeping MCAS disparate inputs are received by the MCAS inputs, the left and right air data/ Partitioned FCCs, the FCCs will disable the MCAS inertial reference units (ADIRUs) receive Comment summary: Commenters function, preventing it from activating direct input from the AOA sensors suggested that MCAS be partitioned for the remainder of that flight. When installed on the left and right sides of such that each FCC would receive input MCAS is disabled in this way, the the airplane, respectively. Each ADIRU from only a single AOA sensor, with the master minimum equipment list transmits the current AOA sensor pilots responsible for switching control (MMEL) does not allow for dispatch of position to the left and right FCCs via from one FCC to the other. the airplane again until the system is databuses. The signal path to each FCC FAA response: The change suggested repaired. is independent of the other FCC (e.g., by the commenters would not improve If a single AOA sensor is damaged the left AOA data does not travel the safety of the airplane, because it due to a bird strike, the bent or broken through the left FCC to reach the right would remove the AOA sensor AOA sensor vane will affect the AOA FCC). comparison feature of the new design measurement. If the AOA sensor vane 2. Comments Regarding Additional and allow a single AOA sensor failure breaks off, the AOA sensor will provide AOA Sensors or Data to activate MCAS as in the original a high AOA value due to a MCAS. Regarding the request to make counterweight falling within the sensor. Comment summary: Numerous the pilots responsible for switching With a significant difference between commenters including the Families of control from one FCC to the other, the valid AOA sensor inputs, the FCCs will Ethiopian Airlines Flight 302 and FAA evaluated the design presented by disable MCAS. Later, if the other AOA BALPA contended that three or more the applicant. It is likely, however, that sensor is damaged (resulting in a high AOA values are required for the system the commenters’ proposal would AOA value), MCAS will already have to be able to continue operating after a increase pilot workload and may also been disabled and there will be no failure of a single AOA sensor. introduce unreasonable reaction time MCAS activation. The sequential failure Commenters assert that if the two AOA requirements for pilot actions. Contrary of two AOA sensors during the same values diverge, the system cannot detect to the commenters’ proposed single- flight is unlikely; even more unlikely which value is erroneous; but with three input configuration, which could allow would be a case where two sensors are AOA inputs, if one value deviates from for MCAS activation following a single damaged simultaneously and the other two, the deviant value could failure, the new MCAS design mandated symmetrically such that there is not a be excluded while the system continues by this AD addresses the unsafe difference sensed between the two AOA to operate using data from the remaining condition by not allowing for that exact sensors as they both transition to similar two sensors. In support of their requests event. high AOA values. Even if such a for additional AOA sensors or inclusion simultaneous and symmetrical failure of a derived value (synthetic AOA), 4. Comments Regarding MCAS were to occur, MCAS would activate some commenters noted that AOA Response After Failure(s) only once. The FAA confirmed through sensors are exposed to the elements or Comment summary: Several testing and analysis during certification other external factors such as bird commenters, including BALPA and the that a single activation of MCAS will strikes. Turkish DGCA, requested that the FAA not prevent continued safe flight and

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landing. The pilots can control the later in the flight, if needed, and that When MCAS is not making a command, change in pitch using only the control MCAS would not be available to the column cutout switches operate like column, or trim inputs, or any perform its intended function. they do on earlier models of the Boeing combination of the two. FAA response: The commenters’ Model 737. It is only during the short The other concern raised by these concerns do not accurately reflect the duration of an MCAS command that the commenters was that if during a flight new MCAS functionality. The new column cutout switches on 737 MAX there is a detected AOA sensor circuit MCAS is designed to activate one time airplanes operate differently than those failure (the first category described for each high-AOA event (above the on other Boeing Model 737 airplanes. previously), MCAS will continue to be MCAS activation threshold). The new The new MCAS includes cross-FCC available to operate with only a single MCAS will activate when there is a monitoring, which detects and stops AOA sensor input for the remainder of high-AOA event (above activation erroneous FCC-generated stabilizer trim that flight. During the remainder of the threshold as previously described), and commands (including MCAS). This flight when the first circuit failure then will reset after the airplane returns protects against an erroneous FCC- occurred, a subsequent independent to a low AOA that is sufficiently below generated stabilizer trim command failure of the other AOA sensor, that is the MCAS activation threshold, such throughout the entire flight, including not detected (second category, e.g., a that it will be available for a subsequent when the column cutout switches are bird strike) and results in an erroneous activation if there is a subsequent high- temporarily disabled. valid AOA input, would be extremely AOA event. As a result, after the new 8. Comments Regarding Erroneous improbable. Nevertheless, if this failure MCAS activates once, it will be MCAS Enable Command combination were to occur (first available for more activations later in category followed by the second the same flight. Only if there has been Comment summary: A commenter category), the outcome would not a failure during the flight that disables expressed concern that the MCAS prevent continued safe flight and MCAS, which is indicated by the SPEED enable command, which disables landing; MCAS would activate only one TRIM FAIL light, will MCAS not be column cutout, could be asserted during time, with the pilots able to control the available during a high-AOA event with a horizontal stabilizer trim runaway due airplane using either the control the flaps retracted. to hardware faults on the stabilizer column, the electric trim switches, or interface. 7. Comments Regarding Disabling of both. This scenario was analyzed and FAA response: The scenario set forth Column Cutout Switches tested by FAA engineers and pilots and by the commenter would result from the found to be compliant with the FAA’s Comment summary: Two commenters simultaneous occurrence of an safety standards. suggested changing the design and erroneous FCC-generated command that function of the column cutout switches disables the column cutout feature and 5. Comments Regarding MCAS on the 737 MAX to be more similar to an erroneous command (from either the Operation at Low Altitude those on earlier Boeing Model 737 pilot or the FCC) to move the stabilizer. Comment summary: A commenter designs. The potential for this combination of stated that MCAS should not operate in FAA response: The column cutout failures to occur simultaneously is certain phases of flight, such as takeoff, switch function of earlier Boeing Model mitigated by integrity monitoring of the climb, and landing, because there 737 models would not allow for MCAS MCAS enable command by the new FCC should not be a potential for a failure to activation. software, which monitors for proper cause the airplane to lose altitude Column cutout switches on earlier FCC performance. Furthermore, during those phases of flight. Another Boeing Model 737 models allow the periodic maintenance checks, commenter suggested MCAS should not flightcrew the capability to interrupt implemented by new tasks in the Boeing operate at low altitudes due to the (cut out) a stabilizer command in one 737 Maintenance Planning Document potential for a wake turbulence direction by making a control column (MPD), verify the function of the cutout encounter or a bird or animal strike. input in the other direction (e.g., an switches (located on the aisle stand) and FAA response: MCAS is functional airplane nose-down stabilizer command the MCAS enable command. Finally, the only during flight with the flaps fully will be interrupted by pulling the cross-FCC monitor also reduces the retracted. When the airplane is at low control column aft). The 737 MAX has likelihood of any FCC-generated altitudes near the airport for takeoff, and the same column cutout feature, but it stabilizer trim runaway command. later during approach and landing, flaps is temporarily disabled during the short 9. Comments Regarding MCAS are extended, typically below 1,000 feet; duration of an MCAS activation. Vulnerability to Single Failures therefore, MCAS is not operational for MCAS operates only during high- the take-off and landing phases of flight. AOA events, which are typically caused Comment summary: A commenter For other phases of flight including by the flightcrew pulling aft on the stated that the system should not be climb, AOA disagreement due to an control column. To allow MCAS to vulnerable to a single failure, and incident such as a bird strike will be operate as intended, the FCC expressed concern that the new MCAS detected by the FCCs, and the FCCs will temporarily disables the column cutout remains vulnerable to a single failure. disable MCAS for the remainder of that switches when MCAS is activated Another commenter asked whether flight. Since the new MCAS function is (makes a command). Without this there is a scenario where any single consistent with the commenters’ temporary disable feature, the MCAS failure, or probable combination of requests, no change to this AD is command to move the stabilizer in the failures, requires the flightcrew to stop necessary. airplane nose-down direction would moving the stabilizer by grabbing the otherwise be interrupted by the column manual stabilizer trim wheel in the 6. Comments Regarding MCAS cutout switches. flight deck; this commenter also asked Availability for Multiple Activations After the MCAS activation, the whether that is in the crew procedure. Comment summary: Two commenters column cutout switches revert to a FAA response: The FAA determined expressed concern that limiting MCAS configuration where control column that the new MCAS is compliant with to a single activation would render inputs will interrupt stabilizer 14 CFR 25.671 and 25.1309, such that MCAS unavailable for more activations commands in the opposite direction. no single failure, or combination of

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failures not shown to be extremely is a phenomenon where the frequency is not necessary to address the unsafe improbable, will prevent continued safe of pilot inputs couples (matches) with condition. flight and landing. Nevertheless, the an inherent airplane frequency. The When the STS (including the speed AFM revisions required by this AD susceptibility of the 737 MAX to PIO/ trim function and the MCAS function) include a runaway stabilizer procedure APC was assessed throughout all of the makes a command to move the with guidance for arresting any FAA flight testing during certification of stabilizer, the flightcrew is aware of the potential runaway stabilizer event. The the 737 MAX. The FAA found the 737 command because the manual trim final step of that procedure is to ‘‘grasp MAX is not prone to PIO/APC. This wheels, located in the aisle stand and hold stabilizer trim wheel.’’ That remains true with and without MCAS between the two pilots in the flight procedure is yet another layer of being available. This also remains true deck, will rotate as the stabilizer moves. protection. during a valid or erroneous MCAS The STS has been a basic design feature activation. of the Boeing Model 737 series for many 10. Comments Regarding MCAS years and is familiar to flightcrews. It is Vulnerability to Sinusoidal AOA Input 12. Comments Regarding Adequacy of not necessary for a system to annunciate Comment summary: Several MCAS to the pilot that it is active. The pilot commenters expressed concern about Comment summary: A commenter can both see and hear the manual trim perceived vulnerabilities of the new was concerned that the new MCAS is wheels rotate when the stabilizer is MCAS implemented by the new FCC inadequate with regard to the rate at moved. Normal MCAS activation occurs software. A commenter expressed which it can respond during a high- only during non-normal flight concern that MCAS is vulnerable to AOA event. The commenter noted that conditions when the airplane is at a sinusoidal AOA sensor input. Another the rate at which the airplane AOA high AOA, and high AOA maneuvering commenter expressed concern that the increases may be too great for MCAS to could potentially already be a high middle value select (MVS) function be effective. workload scenario for the flightcrew. implemented to mitigate erroneous Indications to the pilot that the airplane sinusoidal AOA sensor input as part of FAA response: MCAS has been is at a high AOA include the appearance the new MCAS can diverge or cause a analyzed and tested by the FAA and the of the amber band on the airspeed tape, limit cycle oscillation. Another manufacturer in various scenarios and the appearance of amber pitch limit commenter expressed a concern with flight conditions, which includes indicator (PLI), flashing amber airspeed the MVS algorithm, specifically that if MCAS’s rate of response, as part of the digits on the airspeed tape, the there is a fixed offset between the two certification process, and was found to appearance of the red and black barber AOA sensor values that is less than the meet its intended function, and to be pole on the airspeed tape on the PFD, 5.5-degree threshold that will cause compliant with all applicable 14 CFR increasing column force, and stick deactivation of MCAS, the MCAS part 25 regulations. shaker. function would be utilizing AOA sensor D. Specific Concerns About Alerting Additional annunciation of normal inputs that are offset by up to 5.5 MCAS function during this time could degrees. 1. Comments Regarding Annunciating distract the pilots from recovering from FAA response: The new FCC software MCAS Activation and MCAS Failures this non-normal high-AOA flight compares the two AOA sensor inputs condition. Comment summary: Numerous relative to each other and will disable Regarding the commenters’ request for commenters, including BALPA, the STS (including MCAS) for the annunciation of FCC failures related to Families of Ethiopian Airlines Flight remainder of the flight if the difference MCAS, the system alerts the flightcrew 302, and Ethiopian Airlines Group, between the two exceeds a threshold of by illuminating the Master Caution, commented regarding annunciations 5.5 degrees. The new MCAS also uses system annunciator panel (FLT CONT), and alerting associated with MCAS. an MVS algorithm to address the and SPEED TRIM light. After landing, Some commenters wanted the system potential for a sinusoidal AOA input the SPEED TRIM FAIL and/or STAB changed to add features to make the from a single AOA sensor. To OUT OF TRIM light will be illuminated. pilot aware when MCAS is making a demonstrate compliance with 14 CFR Therefore, the existing system already valid command to the stabilizer system. part 25 standards, the new MCAS was alerts the flightcrew to MCAS failures. They were concerned that without analyzed and tested with various failure The new FCC software monitors annunciation, pilots would have scenarios, including a sinusoidal AOA inputs and outputs for failures, difficulty discerning normal from non- sensor input. The results established including erroneous MCAS commands, normal MCAS activation. They that MVS is effective, that it will not and will disable MCAS for detected suggested illuminating a new light, result in divergence or limit cycle failures. During normal operation, the displaying a message on the primary oscillation, and that the design is FCC commands horizontal stabilizer flight display (PFD), displaying a new compliant and safe. The FAA also tested movement only for three cases: (1) flight mode annunciator, displaying the the new MCAS with the scenario of When the autopilot is engaged and the magnitude of the incremental MCAS AOA sensors offset by up to 5.5 degrees stabilizer is moved to offload column command to the stabilizer, and during certification and found the movement, (2) as part of the speed trim generating a voice annunciation. Other design to be compliant and safe. function during manual flight, commenters suggested that MCAS associated with changes in airspeed, 11. Comments Regarding MCAS failures or deactivations be annunciated and (3) as part of the MCAS function Vulnerability to Pilot Induced by the addition of a warning to alert the during manual flight at high AOA Oscillation crew, a red MCAS FAIL warning, or a outside normal flight conditions. Pilots Comment summary: A commenter loud alert at the same time MCAS is will learn about automated stabilizer expressed concern about the MCAS disabled. trim operation in the special 737 MAX response to a pilot induced oscillation FAA response: The new MCAS training. Pilots have the ability to (PIO). already alerts the pilot of an MCAS override any FCC-generated stabilizer FAA response: PIO, which is also failure. The addition of more trim command, because pilot stabilizer known as airplane/pilot coupling (APC), annunciation of valid MCAS activation trim commands via the thumb switches

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on the control wheel always have some refer to as a gauge). The optional E. Specific Concerns About Crew priority over FCC-generated commands. AOA indicator is a round dial that Interface Finally, if the flightcrew deactivates provides graphic and numeric AOA MCAS by moving the stabilizer trim 1. Comments Regarding Flightcrew position information on both PFDs. Maintaining Control of Airplane cutout switches (located on the aisle Because of this error, only airplanes stand) to the cutout position using the with the (optional) AOA indicator had Comment summary: Numerous commenters stated that the pilot must Runaway Stabilizer NNC (non-normal a functioning AOA DISAGREE alert. be able to maintain control of the checklist), there is no associated This was incorrectly implemented by annunciation. When the FCC generates airplane. A commenter expressed the manufacturer during the display an STS command (speed trim or MCAS) concern that MCAS remains vulnerable software development, and was not after the trim cutout switches are moved to a combination of MCAS commands to the cutout position, the system will identified until after the 737 MAX and pilot inputs that would generate the detect the lack of trim motor response entered into service. repetitive MCAS activations that to the STS command and illuminate the 4. Comments Regarding Display of AOA occurred during the accident flights. master caution light, the SPEED TRIM Indicators The commenters requested that the FAA FAIL light, and the system annunciator ensure that the pilots have the physical panel (FLT CONT). If the autopilot is Comment summary: Several strength required to make column engaged, when the FCC generates an commenters, including BALPA, inputs to counter system failures. These autopilot command after the trim cutout suggested that the optional AOA commenters stated that the system switches are moved to the cutout indicators (gauges) be made basic to the design should be changed to include an position, the system will detect the lack airplane, or offered as a no-cost option, independent means to turn MCAS off of trim motor response to the autopilot so they are available to check accuracy via a dedicated MCAS shutoff switch, command and illuminate the STAB and enhance pilot situational which would be different from and independent of the aisle stand cutout OUT OF TRIM light. Therefore, the awareness. Another commenter asked switches. The commenters suggested requested additional annunciation is not why there is no standby (third) AOA including a guard that would illuminate necessary. indicator. the MCAS shut-off switch when MCAS 2. Comments Regarding Display of AOA FAA response: The AOA position is inoperative and provide a DISAGREE Alert indicators are not required for corresponding aural warning. Comment summary: Several compliance with design standards with FAA response: None of the identified commenters, including the UAE GCAA, regard to pilot situational awareness. additional system changes are necessary requested that the AOA DISAGREE alert The cues to the pilots as the airplane to achieve the objective that the be displayed in the pilot’s primary field approaches stall are inherent in other flightcrew must be able to maintain of view and/or on the Head Up Display airspeed and attitude information control of the airplane. The new MCAS (HUD). displayed on the PFDs, which provide design and associated pilot procedures FAA response: Paragraph (j) of this situational awareness and are described and training focus on the pilot’s ability AD requires installation of new MDS earlier in this preamble. In response to to control and remain in control of the software including functionality to the question about a third AOA airplane. The new MCAS has several features to display the AOA DISAGREE alert on indicator, the FAA notes that there is no each pilot’s PFD if the left and right ensure that the pilot maintains control. requirement to have any AOA indicator AOA values differ by more than 10 With the new MCAS design, pilot for compliance with 14 CFR part 25 degrees for more than 10 seconds. The inputs to the trim switches do not reset 5 The FAA has not changed PFDs are in the primary field of view in standards. MCAS. Therefore, the new MCAS is not front of each pilot, and are therefore this AD based on this comment. vulnerable to the same repetitive cycles consistent with the commenters’ 5. Comments Regarding Additional of MCAS activation that occurred request. Regarding the message also Aural Alerts during the accident flights. showing on the HUD, the FAA notes The new MCAS design will (1) detect that HUDs are optional equipment. For Comment summary: A commenter failures and not command MCAS if airplanes with HUDs installed, updated stated that the AOA DISAGREE alert, as those failures occur; (2) result in only a HUD software will display AOA well as IAS DISAGREE and ALT single activation of MCAS for certain DISAGREE on the HUD if it is being DISAGREE alerts, need a corresponding dual failures; and (3) in the event the displayed on the PFD. The HUD aural alert for immediate two-sense airplane experiences multiple high AOA software is not required by this AD. No awareness of the condition by the events, it will limit the stabilizer change to this AD is necessary based on flightcrew. movement so the pilot can always this comment. maintain control of the airplane using FAA response: The AOA DISAGREE, only the control column. 3. Comments Regarding Omission of IAS DISAGREE, and ALT DISAGREE The FAA also notes that the Runaway AOA DISAGREE Alert From 737 MAX alerts show on both PFDs in the pilots’ Stabilizer NNC (as revised and required Comment summary: Several primary field of view. This design has by paragraph (h) of this AD) is a means commenters asked why the AOA been assessed, tested, and found for a pilot to stop MCAS commands and DISAGREE alert was not included in the compliant with 14 CFR part 25. The any electric command to the stabilizer original 737 MAX design. FAA has not changed this AD based on trim motor. That procedure is another FAA response: The AOA DISAGREE this comment. safety feature in the unlikely event the alert is a standard design feature on the airplane experiences erroneous 737 NG fleet (600/700/800/900/900ER) stabilizer trim movement. and was intended to be standard for the 5 This preamble addresses elsewhere a comment Regarding the comments suggesting a 737 MAX, but it was instead suggesting the addition of a third independent AOA dedicated switch to disable MCAS to erroneously linked by the manufacturer input, which would be required to provide data to include a guard, light, or aural warning, to an optional AOA indicator (which a third independent AOA indicator. the FAA notes that when MCAS is

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disabled due to detected faults, the if the pilot moves the aisle stand cutout evaluate the ability to control the Master Caution and system annunciator switches to the cutout position; in that airplane for continued safe flight and panel (FLT CONT), as well as the event, the pilot has the option to use landing. These flight test conditions and SPEED TRIM light on the P5 overhead manual trim to move the stabilizer. As the associated analysis included panel, will be illuminated. The new discussed in the next paragraph, manual maximum out-of-trim conditions well MCAS is compliant with 14 CFR part 25 trim forces have been assessed and beyond those possible for any failure certification standards and addresses deemed acceptable. conditions in the new MCAS design and the unsafe condition, so it is not 3. Comments Regarding Manual Trim included the most critical aircraft necessary to change the design to add a Forces configurations and airspeeds to the dedicated switch to disable MCAS or operational airspeed limit of the flight add an additional light or aural alert. Comment summary: Many envelope (referred to as Vmo/Mmo). The commenters, including the Allied Pilots FAA determined that manual trim 2. Comments Regarding Function of Association, ALPA, BALPA, Ethiopian Aisle Stand Cutout Switches wheel forces meet FAA safety standards Airlines Group, and the UAE GCAA, and do not require exceptional pilot Comment summary: Numerous expressed concerns regarding the 737 skill or strength nor any special or commenters suggested changing the MAX manual trim system and the forces unique handling techniques as design of the aisle stand stabilizer trim required to control and trim the aircraft suggested by some of the commenters. cutout switches to resemble the design following a failure of the STS (including Improvements to the Runaway on pre-MAX versions of Model 737 MCAS). Some questioned the Stabilizer non-normal procedure airplanes. On those earlier Model 737 mechanical advantage provided by the proposed in the NPRM and mandated airplanes, two guarded switches on the manual trim system and whether it had by this final rule include steps to help aft end of the center aisle stand, aft of been evaluated in flight testing. A ensure column forces remain the throttle levers, are used to stop commenter stated that it takes 15 turns manageable and reduce manual wheel electric commands to the stabilizer trim of the pitch trim wheel to get just one trim forces in the unlikely case where motor. The pilots are directed to use the degree of horizontal stabilizer manual trim may be needed. switches by two NNCs: Runaway movement, and some pilots may lack Additionally, this AFM procedure and Stabilizer and Stabilizer Trim the strength to make those turns if the pilot training emphasize the first Inoperative. In both procedures, the required force is too high. The priority in an emergency is to maintain pilot is directed to ‘‘place both STAB commenter suggested pilots should be control of the airplane, and also include TRIM cutout switches to CUTOUT.’’ On required to take a yearly strength test to specific information about the manual the earlier models of the Boeing Model determine whether they are capable of trim system including techniques for 737, the switches have distinct pulling a yoke or turning the pitch trim effectively using manual trim. functions (labeled ‘‘main’’ and ‘‘auto’’) wheel in simulated emergency Therefore, the FAA has made no where one (auto) would cut out all FCC- conditions. changes in finalizing this AD related to generated stabilizer commands FAA response: Following the the manual trim system or related AFM (autopilot and speed trim) and the other Ethiopian Airlines accident, the 737 non-normal procedures. (main) would cut out pilot-generated MAX manual trim system design and commands (from the pilot thumb force requirements were an area of 4. Comments Regarding Availability of switches). On the 737 MAX, however, intense focus by the Ethiopian Aircraft Automation After MCAS Failure the switches are wired in series, and Accident Investigation Bureau, the FAA, both perform the same function Boeing, and other CAAs, which Comment summary: A commenter (primary and backup): To cut out all continued throughout the FAA’s stated that the autopilot and autothrottle electric commands to the stabilizer evaluation and testing of the new FCC should be available following an MCAS (both FCC-generated commands and software and new MCAS during failure. The commenter expressed pilot commands). The commenters certification. The data from the concern that MCAS will be triggered asserted that the configuration of the Ethiopian Airlines accident indicates routinely due to turbulence and gusts earlier (pre-MAX) Boeing Model 737 that the high trim wheel forces during cruise, and its shutdown would airplanes would allow the pilot to experienced during that accident were render the autopilot inoperative. The disable MCAS commands while the result of significant horizontal commenter noted that when autopilot is retaining the ability to make electric stabilizer mis-trim combined with not available, airplanes are prohibited trim inputs using the thumb switches. excessive airspeed. The new FCC from flight at higher altitudes where The commenters expressed concern that software limits the maximum mis-trim airplanes fly with reduced vertical pilots would be required to use manual that could occur for any foreseeable separation minima (RVSM). trim for the remainder of that flight. failure of the STS, thus ensuring the FAA response: In most cases, FAA response: No change to the pilot can maintain control of pitch using autopilot and autothrottle are available design or this AD is necessary to the column only, without requiring following an MCAS failure. Flight address the commenters’ concerns. The exceptional pilot skill, strength, or testing of the new MCAS has new MCAS has redundancy (receives alertness. Additionally, the FAA demonstrated that it will not be inputs from two AOA sensors and is evaluated the manual trim system for triggered due to turbulence and gusts. implemented by two FCC computers) the unlikely event that manual trim will The new MCAS design is such that and will automatically disable MCAS be necessary. This included detailed following certain MCAS failure for the remainder of the flight if certain analysis of manual trim wheel forces as scenarios, the system will allow for failures are detected. For detected a function of both dynamic pressure and engagement of the autopilot and failures where MCAS stops making out-of-trim state, testing to measure and autothrottle. Flightcrew training and commands, the pilot does not use the assess the strength capability of an procedures identify when the flightcrew aisle stand cutout switches, and retains anthropometric cross-section of male may attempt to engage the autopilot the ability to use thumb switches to and female subjects, and FAA flight and/or autothrottle. If the Runaway control the stabilizer. The only time the testing to quantitatively validate manual Stabilizer NNC is used, the use of thumb switches would be unavailable is trim wheel forces and qualitatively autopilot is prohibited by the procedure.

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5. Comments Regarding Selection of Air flaps and cause controllability from other CAAs and from Boeing), Data Source problems. The FAA has not changed which considered a myriad of similar Comment summary: A commenter this AD regarding this issue. aspects as the procedures were developed and evaluated. Additionally, wanted the air data system to be revised F. Suggestions for Crew Procedure to allow for selection of offside data if the procedures were evaluated during Changes FAA certification, including human onside data is erroneous (i.e., the factors evaluations to determine captain can select to display first 1. Comments Regarding AFM Crew compliance to 14 CFR 25.1302, and officer’s data, or vice versa), and ideally Procedure Adequacy system safety assessments to determine to automate it to prevent the display of Comment summary: Several compliance to 14 CFR 25.1309. The erroneous data. commenters, including BALPA, FAA convened a team of test pilots, FAA response: This comment NATCA, ALPA, Boeing, the Allied operational pilots, and human factors regarding the air data system is not Pilots Association, the JEMOG, experts during the development of the related to the unsafe condition Ethiopian Airlines Group, A4A, and AFM procedures specified in the addressed by this AD. The Boeing 737 SWAPA, requested that the FAA modify proposed AD. The FAA convened a the emergency and non-normal air data system is federated such that similar team to consider each procedures contained in the proposed independent air data (altitude, airspeed, procedural comment made during the AD. These comments covered several of and AOA) from the captain’s side is NPRM comment period and to the proposed checklists, with an used to provide information on the determine if changes were warranted to emphasis on the Airspeed Unreliable captain’s PFD, while independent air improve safety. data from the first officer’s side is used and Runaway Stabilizer checklists. The A4A and SWAPA expressed concern to provide information on the first comments included requests to make that there are too many recall items in officer’s PFD. The unsafe condition small changes involving typographical the Runaway Stabilizer non-normal addressed by this AD concerns a single errors, to add information to checklists, procedure, and included a suggestion high erroneous AOA generating to simplify checklists, to shorten or for how to reduce the number of steps. repetitive MCAS behavior, which, in reduce the number of memory items, The suggestion included combining combination with multiple flight deck and to develop checklists for certain some recall items to achieve fewer effects, could affect the flightcrew’s specific failure cases. Three numbered steps, but with multiple ability to accomplish continued safe commenters, including BALPA and embedded actions in each recall item, flight and landing. The requirements of Ethiopian Airlines Group, such that the suggested changes would this AD address the MCAS issue. recommended providing a combined result in the same number of required Airspeed Unreliable and Runaway flightcrew actions. The FAA agrees that 6. Comments Regarding Suppression of Stabilizer checklist for certain specific Overspeed Warning it is desirable to minimize recall items failure conditions. when appropriate. The recall steps in Comment summary: A commenter Finally, ALPA commented that, while the non-normal procedures required by stated that the warning system needs to it supported in principle the potential paragraph (h) of this AD reflect be revised so that the overspeed aural changes to the Unreliable Airspeed flightcrew actions required to address a warning can be suppressed manually by checklist described in the addendum to runaway stabilizer condition. Based on the flightcrew. the draft 737 FSB Report, it cannot the FAA’s evaluation and in FAA response: This comment is not provide support or opposition to any coordination with human factors related to the unsafe condition such changes without reviewing the specialists, the FAA determined that the addressed by this AD. Like the airspeed checklist as modified. ALPA proposed commenters’ proposed changes would and stick shaker, the overspeed aural that the FAA release the final Airspeed complicate the recall steps and would warning is federated in a left/right Unreliable Checklist for public review increase the likelihood that a critical configuration aligning with the captain’s and comment after modification with flightcrew action is forgotten or missed. and first officer’s sides of the airplane. the potential refinements described in The FAA considered all of the The system meets the certification the addendum. commenters’ requests in the context of standards applicable to this airplane FAA response: The FAA has made crew workload, clarity of instruction, and was certificated without a provision several changes to the checklists, taking consistency with training objectives, for suppressing the aural warning. into consideration not only comments and consistency with other procedures provided in the context of the NPRM, contained in the AFM. The FAA 7. Comments Regarding Crew Procedure but also in response to the outcomes To Extend Flaps declines the request to combine from the FAA FSB evaluation. The checklists because checklists must be Comment summary: Two commenters inputs from the FAA FSB were the applicable to all potential failure suggested adding a crew procedure to result of collaboration with other CAAs conditions, not just the specific failure extend the flaps in the event of an during the JOEB. The JOEB conducted conditions noted by the commenters. MCAS failure. They noted that MCAS is an extensive evaluation of the proposed Additionally, the failure conditions available only when the flaps are procedures and training conducted by a where a combined checklist might be retracted, which indicates that the wide variety of crews, including line useful were evaluated by multiple airplane does not need MCAS when the pilots with levels of experience ranging flightcrews, resulting in a conclusion by flaps are extended. from high to low and regulatory pilots the FAA that, primarily due to the new FAA response: It is not necessary to from four separate CAAs during the MCAS required by this AD, the order add a new flightcrew procedure for NPRM comment period. and content in which these two extending the flaps in order to counter The AFM procedures specified in the checklists were accomplished is not an MCAS failure. With the new MCAS proposed AD were the result of critical to continued safe flight and design, time-critical crew procedures procedural development conducted by landing. are not required to mitigate MCAS FAA test pilots, human factors, and The FAA made minor changes to the failures. Furthermore, extending the operations personnel (along with other procedures that were proposed in the flaps at high airspeeds could damage the engineering and operational experts NPRM. The changes simplify and

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correct grammatical and typographical 2. Comments Regarding Crew Procedure position in the flight deck, leading to errors in, the Airspeed Unreliable non- To Disable Stick Shaker possible distraction from their primary normal checklist (figure 2 to paragraph Comment summary: Several duties to safely control and monitor the (h)(3) of this AD) as follows: commenters, including the Allied Pilots aircraft. Furthermore, inclusion of these • Removed the words ‘‘using Association, ALPA, BALPA, Ethiopian additional steps would add cognitive performance tables from an approved Airlines Group, and the UAE GCAA, and physical workload to an already source,’’ which contradicted the next expressed concerns regarding the substantial Airspeed Unreliable non- sentence. attention-getting nature of the stick normal procedure, and errors in locating • Corrected a typographical error to shaker and requested a change to the and pulling the correct circuit breaker specify actions if the ‘‘captain’s and first procedures to include a means to may lead to other airplane hazards. Balancing the concerns associated with officer’s altitude indications are both suppress an erroneous stick shaker, adding a procedure to pull circuit unreliable’’ instead of the proposed including procedures to pull the breakers against the distraction of an ‘‘captain’s or first officer’s altitude associated stick shaker circuit breaker. erroneous stick shaker, the FAA has indications are both unreliable.’’ In contrast, a commenter expressed a • concluded that the design is compliant Revised a note to correct a concern with the possible safety risks of and safe, and therefore no change to the typographical error; the corrected text including a procedure to pull the stick proposed non-normal procedures refers to ‘‘DA/MDA,’’ while the previous shaker circuit breaker in order to silence related to silencing the 737 MAX stall text referred to ‘‘DH/MDA,’’ and revised the warning. warning is required for this AD. the last sentence for clarity. FAA response: The FAA infers that • Revised a sentence to specify that the commenters are suggesting there is 3. Comments Regarding Changes the pitch bar may ‘‘automatically’’ be an unacceptably high flightcrew Associated With Crew Procedures removed, thus clarifying that removal workload when stick shaker is activated Comment summary: The FAA does not require pilot action. erroneously. The 737 stall warning/stick • received comments from A4A, JEMOG, Revised a sentence to specify ‘‘An shaker is, by design, attention getting Air China, Ameco, and several other AFDS pitch mode’’ instead of ‘‘Selection and can be a distraction during an commenters regarding the new AFM of an AFDS pitch mode.’’ erroneously high-AOA event. However, • non-normal procedures that were Added a note to specify ‘‘only use after careful evaluation, the FAA has not primarily administrative in nature flight director guidance on the reliable changed the AFM non-normal rather than specific recommended PFD.’’ procedure to include pulling the stick changes. A commenter recommended The FAA also revised the ALT shaker circuit breakers in this final rule, referring to the AFM non-normal Disagree non-normal checklist (figure 8 for the following reasons. procedures as ‘‘updates’’ versus ‘‘new’’ to paragraph (h)(9) of this AD) to correct The FAA evaluated all failure as stated in the NPRM. Another a typographical error in the proposed conditions of the new FCC software as commenter stated that the proposed AD. The corrected text refers to ‘‘DA/ part of certification of the proposed new non-normal procedures were MDA,’’ while the proposed text referred system changes. The new FCC software different and more complicated than to ‘‘DH/MDA.’’ removes the potential for repeated, previous Boeing Model 737 non-normal To the extent that ALPA suggests the uncommanded MCAS inputs in the procedures. Another commenter addendum contained insufficient presence of an erroneous high AOA disagreed with the FAA’s proposed information to provide a meaningful sensor input. This new design therefore allowance to insert the figures comment, the FAA notes that the removes the most significant contributor containing the non-normal procedures addendum identified the areas of to unacceptably high flightcrew directly into the AFM. A4A expressed potential checklist refinement and the workload. With the new FCC software concern with the memory items in the reasons why refinement may be on the 737 MAX, the FAA tested and proposed AFM non-normal procedures necessary. The JOEB’s operational assessed all remaining flight deck and use of Quick Reference Cards evaluation of the proposed checklists effects, including erroneous stick (QRCs) by some operators. Finally, a generated potential refinements that did shaker, during all foreseeable failure commenter requested that the FAA not result in any substantive change to conditions, including high-AOA sensor assess the proposed procedures in light the checklists proposed in the NPRM. failures during the most critical phases of one pilot instead of a crew of two. Rather, the results of the evaluation of flight (such as during takeoff or go- FAA response: While it is true that indicated that minor revisions to the around). With the remaining flight deck some of these non-normal procedures unreliable airspeed checklist, which are effects and associated crew workload, can be viewed as updates to existing reflected in this AD, may be these failures and effects were found procedures, such as those in the appropriate. As such, there was no need compliant and safe. operator’s Quick Reference Handbook, for the FAA to publish the ‘‘final The FAA considered the commenters’ this AD addresses AFM non-normal checklist’’ with the 737 FSB Report. concerns that an erroneous stick shaker procedures that are part of the required However, because the FAA was aware may pose a distraction for the crew, and type design change to the 737 MAX. The that additional information obtained evaluated that scenario with procedures FAA is mandating removal of old, and during the operational evaluation could that include steps to silence an replacement with new, AFM non- have an impact on the final checklists, erroneous stick shaker stall warning via normal procedures. These AFM changes it provided notice of the findings in an a circuit breaker pull. The FAA finds will result in corresponding changes to addendum to the 737 FSB Report and that an erroneous stick shaker, while it flightcrew training and operations sought comment from the public. The may pose a distraction to the flightcrew, materials including applicable Quick FAA finds that the addendum provided does not affect controllability of the Reference Handbook Non-Normal sufficient information for commenters to airplane. The stick shaker circuit Checklists such that they reflect these assess the potential revisions and offer breaker locations also do not meet FAA new AFM procedures. alternatives to the proposed checklist to requirements for convenient operation Regarding the comment about the address the concerns suggested by the for emergency controls for the complete added complexity in the new AFM non- operational evaluation. range of pilots from their normal seated normal procedures compared to

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previous Boeing Model 737 procedures, change to this AD is necessary based on regarding vulnerable AOA vanes. The as previously noted the AFM this comment. commenters requested expansion of the procedures specified in the proposed one-time AOA sensor system test 5. Comments Regarding Timeliness of AD were thoroughly vetted by the FAA (required by paragraph (l) of this AD) to Flightcrew Procedures and others, as previously described in a regularly scheduled repetitive action the ‘‘Related Actions’’ section. The AFM Comment summary: Boeing (not just one time before the airplane is procedures are required by this AD as recommended that the FAA revise a returned to service). part of the 737 MAX design changes; sentence in the sixth paragraph of the FAA response: The vane-style AOA their complexity has been reduced Proposed Design Changes section of the sensor used on the 737 MAX is a during the FAA’s certification activity, NPRM to clarify the use of ‘‘timeliness’’ common instrument installed on many and they have been validated by the as it relates to the flightcrew performing transport airplanes. The existing FSB during the JOEB evaluation. a non-normal procedure. Boeing stated preflight walk-around inspection of the To facilitate immediate incorporation that there is an element of timeliness airplane includes a visual check of the of new AFM non-normal procedures, expected in flightcrew responses to all condition of the AOA sensors. These the FAA allows for copies of the figures non-normal events. AOA sensors include electrical circuits to be inserted directly into the existing FAA response: The FAA intentionally that measure the angle of the sensor. AFM if needed. That provision is referred to the ‘‘timeliness’’ of the The position-sensing electrical circuits specified in paragraph (h) of this AD. flightcrew performing a non-normal are continuously monitored and can The FAA agrees that revised AFMs procedure in the proposed AD. The 737 detect if an electrical circuit is should be provided to operators, and the MAX flight control design at the time of compromised. The AOA sensors also FAA expects those revisions will be the Lion Air and Ethiopian accidents include electrical heaters in the body of available from Boeing following relied on pilot use of secondary flight the sensor and within the vane that issuance of this final rule. controls (i.e., the electric trim switches) aligns with local airflow and rotates The FAA did not assess use of QRCs, in a particular way (large continuous within the sensor as AOA changes. The which are operator specific. Should an commands versus several short duration electrical current to the AOA heaters is operator wish to use QRCs that deviate commands) or use of the Runaway monitored to detect a heater failure. The from the AFM procedures specified in Stabilizer non-normal crew procedure left and right AOA sensor values are not paragraph (h) of this AD, the operator (using aisle stand cutout switches or compared before flight because AOA must coordinate with its principal grasping the manual trim control sensors can be moved by winds. The left inspector or responsible Flight wheel), in a relatively short amount of and right AOA sensor values are Standards Office and submit a request time, for certain failure conditions compared during flight and before the for an alternative method of compliance (erroneous MCAS command) to retain data is used by MCAS. If the difference (AMOC) to the requirements of this AD. aircraft control and ensure continued between them is more than 5.5 degrees, Finally, while most tasks in the flight safe flight and landing. Control of the MCAS will be disabled. If an AOA deck could be accomplished by a single airplane during this failure scenario sensor is damaged while at the gate, the pilot, the FAA notes that the 737 MAX depended on these timely crew actions. typical damage would be a bent or is certified with two pilots as the With the new MCAS implemented by broken vane. This damage could be minimum crew, in accordance with 14 the FCC software required by this AD, detected during the preflight inspection. CFR 25.1523. basic control of the airplane is ensured If the heater circuit is damaged, the No change to this AD is necessary for all potential failure conditions heater failure will be annunciated. If a based on these comments. through the use of only the primary vane is bent only a small amount, there 4. Comments Regarding Disabling flight controls (i.e., control column), may be small differences between the captain’s and first officer’s altitude and Elevator Feel Shift without the need for particular and timely pilot reactions on non-primary airspeed indications. Paragraph (l) of Comment summary: A commenter controls. Therefore, the FAA has this AD requires a one-time check of the requested that the flight control system determined that no change to this AD is AOA sensors to verify that the AOA disable differential feel in the event it is warranted. sensors are calibrated correctly and the triggered falsely by an erroneous high AOA heaters are working properly. AOA condition. G. Suggestions Regarding Monitors/ Scheduled checks of the AOA sensors FAA response: The FAA infers the Maintenance/Operations are not necessary due to the preflight commenter is referring to the Elevator inspections, the continuous circuit Feel Shift (EFS), which is associated 1. Comments Regarding AOA Sensor Checks and Monitoring monitors, and the pilots’ use of altitude with identification of a stall on 737 NG and airspeed data affected by the AOA and 737 MAX airplanes based on AOA Comment summary: Several sensors. sensor data. Although both MCAS and commenters offered input regarding EFS use AOA data, only MCAS can suggested additional checks and 2. Comments Regarding AOA Sensor move the horizontal stabilizer. The EFS monitoring of the AOA sensors, Calibration and Testing changes control column feel force, but including doing a visual inspection Comment summary: A commenter does not use the horizontal stabilizer before flight, continuously monitoring requested improved calibration and trim system to initiate the changed feel the AOA sensor electrical circuits, testing of critical AOA sensors. force. This comment is unrelated to comparing AOA sensor values before FAA response: The Collins Aerospace MCAS and the unsafe condition flight, and continuously monitoring Component Maintenance Manual addressed by this AD. The FAA them throughout the flight. The (CMM) that is used for calibrating the considered this system during the commenters asked whether the monitors 737 MAX AOA sensors as they are analysis, flight testing, and human can detect damage (e.g., damage that assembled has been updated with a new factors assessments performed prior to occurs while at the gate) to an AOA final check to verify that the AOA approval of the new MCAS sensor while on the ground. The sensor has been calibrated correctly. implemented by the FCC software commenters noted that the NPRM did This new check uses a simple required by paragraph (g) of this AD. No not mention ground operations actions independent electrical test that will

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detect whether the more sophisticated 4. Comments Regarding Use of for a dual purpose. On that 737–300 calibration equipment was configured Erroneous AOA Sensor Data airplane, a single warning served to and used correctly. The AOA sensor is Comment summary: A commenter annunciate two different, unrelated tested on the airplane using the AOA noted that it would be preferable to issues: Takeoff configuration warning sensor system test in the AMM. This test suppress the effects of a faulty AOA and cabin altitude warning, with two is specified in Boeing Special Attention sensor by declaring it failed and associated distinct flightcrew Service Bulletin 737–00–1028, dated disregarding it. procedures. The function of the STAB July 20, 2020, which is required by FAA response: The unsafe condition OUT OF TRIM light implemented by paragraph (l) of this AD. The test is identified in this AD is addressed by the this AD (it is in the FCC software) is associated with only one flightcrew required to ensure that all 737 MAX required actions, including installation procedure (the Stabilizer Out of Trim AOA sensors are properly calibrated of the new FCC software (with the new NNC required by this AD). Per that and the heaters are operational prior to MCAS) which compares AOA sensor data supplied to it. The actions required procedure, if the light is illuminated on return to service. Therefore no change to the ground the flightcrew is directed to this AD is necessary based on this by this AD do not change the existing 737 MAX air data system, which not takeoff. Therefore, a new separate comment. includes monitoring and determination light is not required. No change to this 3. Comments Regarding Discerning of AOA sensor failures, which was AD is necessary based on these AOA Sensor Failures certificated without the capability comments. suggested by the commenter. 6. Comments Regarding Periodic Testing Comment summary: The Turkish of MCAS DGCA, Ethiopian Airlines Group, and 5. Comments Regarding Use of STAB other commenters proposed to integrate OUT OF TRIM Light Comment summary: A commenter information from the various AOA Comment summary: Several suggested that MCAS have either an automatic or a manual self-test that sensor electrical circuits and other data commenters, including ALPA and the could be tied to the stall warning system available on the airplane to establish UAE GCAA, had questions and test. when there is an AOA sensor failure concerns regarding the STAB OUT OF TRIM light function and use. The FAA response: Based on the and when data from the AOA sensor suggestion to tie a self-test to the stall should not be used. Data from the commenters noted the new use of the light to annunciate FCC failures, and warning system test, the FAA infers that Ethiopian Airlines Flight 302 accident had questions about where the light is the commenter is suggesting that this shows a detected AOA heater failure located, when the light would be test be conducted every day. Frequent coincident with the sensed AOA illuminated, whether pilots would see testing of MCAS is not required to transitioning rapidly to a large AOA it, and whether depressing the RECALL comply with FAA reliability 6 value. The commenters also noted that button would be required. Other requirements (14 CFR 25.1309). Even with the failure of the AOA sensor commenters were concerned that a light though MCAS is intended only for use heater, the AOA sensor is more with a dual meaning could lead to what during non-normal flight conditions, the vulnerable to icing and consequently they referred to as a ‘‘Helios’’ type of elements of the air data and flight could provide unreliable AOA output event, and therefore there should be a controls system associated with MCAS values. Proposed scenarios that would new separate light. are used during every flight and are cause AOA sensor data to be FAA response: On the 737 MAX, there continuously monitored. These include disregarded include the following: is one STAB OUT OF TRIM light AOA sensors and associated wiring, Heater failure, heater failure combined located on the captain’s forward ADIRUs, databuses, FCCs, and FCC- with a rapid change in the AOA sensor instrument panel above the inboard generated stabilizer trim commands, position to a position consistent with display. Per figure 6 to paragraph (h)(7) such as STS commands or autopilot vane departure, AOA disagree at 90 of this AD, on the ground the light will commands. An existing CMR (22–CMR– knots during takeoff, unreasonable AOA illuminate if there is a partial failure of 01 in the Boeing MPD) does an for flight conditions, and an AOA that an FCC. In flight, the light will operational check of speed trim and disagrees with the estimated (synthetic) illuminate if the autopilot does not set stabilizer trim discrete associated with the FCC computers. Certification of the AOA. the stabilizer trim correctly. Dispatch is prohibited when the STAB OUT OF new MCAS required implementing a FAA response: FAA regulations do TRIM light is illuminated while on the new CMR (22–CMR–02), which requires not require the integrated failure ground. With electrical power on, for periodic testing to verify proper detection capability requested by the certain failures of an FCC, the light will functioning of the stabilizer trim enable commenters, and the 737 MAX air data be illuminated continuously, such that ground path and autopilot arm cutout system does not include this capability. no recall action is required of the pilot switch. In summary, while MCAS is not The FAA has determined that no change to have the light annunciate a fault. The explicitly tested each flight, any to this AD is necessary because heater light is in a location that is visible by problem with AOA, ADIRU, FCC, failures are annunciated, and the both pilots. software, etc., will be evidenced Unreliable Airspeed NNC provides The FAA infers that the commenter’s immediately by existing monitors and guidance for pilots to establish whether reference to Helios is regarding the alerts to be resolved by maintenance there is reliable available data. Helios Airways Flight 522 accident on prior to subsequent dispatch, and August 14, 2005,7 related to confusion therefore does not need to be tested. The 6 Figure 56, ‘‘AOA Values During the Beginning with a single flight deck warning used FAA has not changed this AD based on of the Flight,’’ of Report No. AI 01/19, ‘‘Interim this comment. Investigation Report on Accident to the B737–8 7 Hellenic Republic Ministry of Transport & (MAX) Registered ET–AVJ operated by Ethiopian Communications Air Accident Investigation & 7. Comments Regarding Maintenance of Airlines on 10 March 2019,’’ dated March 9, 2020, Aviation Safety Board (AAIASB) Helios Airways MCAS of the Federal Democratic Republic of Ethiopia Flight HCY522 Aircraft Accident Report, dated Ministry of Transport Aircraft Accident November 2006 (https://data.ntsb.gov/Docket/ Comment summary: A commenter Investigation Bureau. ?NTSBNumber=DCA05RA092). noted that there is little mention of

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maintenance in the NPRM. Another Boeing notified 737 MAX operators 10, 2020, the FAA published the FAA- commenter asked whether dispatch is that these documents were revised and approved Boeing 737 MAX B–737–8/–9 prohibited after MCAS failure. Another published via customary MMEL, Revision 2, after public notice commenter inquired about procedures communication methods. U.S. part 121 and opportunity for comment. The 737 for recording, diagnosing, and repairing and part 135 operators must use current MAX MMEL does not allow dispatch the system before another flight. CMRs per their OPS SPECS D072 with the STS (which includes MCAS) FAA response: Design changes Aircraft Maintenance—Continuous inoperative, and it does not allow mandated via an AD often have new or Airworthiness Maintenance Program dispatch with the position sensing revised maintenance documents (CAMP) Authorization. Continued circuit in an AOA sensor inoperative. associated with them. eligibility for a CAMP authorization The monitoring that would prevent this All of these 737 MAX maintenance- depends on the operator incorporating dispatch would also detect a failure in related documents have been revised: MPD revisions (which include CMRs) the communication between the AOA • Boeing 737 Fault Isolation Manual into their maintenance programs. sensors and the MCAS function in the (FIM) 8. Comments Regarding Oversight of FCCs. The MMEL, which includes AOA • Boeing 737 Aircraft Maintenance Maintenance Program sensor heaters, allows for limited Manual (AMM) dispatch with inoperative AOA heaters, Comment summary: A commenter • Boeing 737 Maintenance Planning provided the airplane is not operated in asked who and what documents and/or Document (MPD) known or forecast icing conditions. No procedure ensures that the maintenance • FAA Maintenance Review Board change to this AD is necessary based on program is enforced. Report FAA response: For airplanes this comment. • FAA Master Minimum Equipment registered in the United States, List (MMEL) (referenced in paragraph 11. Comments Regarding Inclusion of operators must have an approved (i) of this AD) AOA Sensor Heaters in MMEL • maintenance program and must adhere Collins Aerospace Component to it. The FAA oversees U.S. operators. Comment summary: The UAE GCAA Maintenance Manual (CMM) for AOA Foreign operators are regulated and noted that currently ‘‘AOA heating Sensor overseen by the civil aviation authority system, flight control system, and AP/ This AD requires accomplishment of of their country. YD’’ are MMEL ‘‘go’’ items in most certain Boeing service bulletins that cases, except for long-range operations reference sections of the AMM. 9. Comments Regarding Redundancy in the Master Minimum Equipment List and in-icing conditions. The UAE Paragraph (i) of this AD requires actions GCAA noted that it is sometimes related to the MMEL. The FAA has Comment summary: A commenter difficult for flightcrews to avoid icing in released a maintenance Safety Alert for noted that figure 10 to paragraph (i) of some flight conditions. The UAE GCAA Operators (SAFO), SAFO 20015, Boeing the proposed AD contained redundant asked that the FAA and Boeing make 737–8 and 737–9 Airplanes: Return to information. The commenter stated that these items ‘‘no go’’ in the MMEL. Service,8 that identifies related within figure 10 to paragraph (i) of the documents. proposed AD, both step (2) and step (8) FAA response: As previously noted, U.S. airlines must have an approved specify that the autopilot disengage the FAA approved revisions to the maintenance program as a condition of aural warning system must be operating MMEL that removed provisions for their approval to operate in the U.S. In normally for dispatch. The commenter dispatch related to MCAS failures. The response to the comment pertaining to added that item 22–10–02 (which is MMEL continues to include provisions operation after MCAS failure, the MMEL discussed in note 2 to paragraph (i) of for limited dispatch for other unrelated does not allow dispatch of the airplane the proposed AD; now note 3 to degradation of the flight control system, with failure of the STS, which includes paragraph (i) of this AD) was deleted in the autopilot, and yaw damper. MCAS. Maintenance will utilize the revision 2 of the MMEL. Regarding the AOA heating system, no FIM and AMM to assess the system, FAA response: The FAA agrees that changes are required for MMEL item isolate the fault, resolve the issue, and the items mentioned are redundant. 30–31–02. The MMEL currently states then return the airplane to service. However, this redundancy does not that the AOA sensor heaters may be For shop repair of AOA sensors, the affect compliance with the AD. In inoperative, provided the aircraft is not Collins Aerospace CMM was updated to addition, this redundancy will be operated in known or forecast icing add a final check using different addressed in the next revision of the conditions. However, if icing conditions equipment to ensure the sensor was not MMEL. No change to this AD is are encountered, the potential effects mis-calibrated. necessary based on this comment. due to unheated vanes, including to air For scheduled periodic maintenance, data and to MCAS, do not rise to a 10. Comments Regarding Inclusion of two new tasks are included in the FAA’s hazardous level. AOA Sensors in MMEL Maintenance Review Board Report and in the Boeing MPD. The first is Item 22– Comment summary: A commenter 12. Comments Regarding Typographical 011–00 in the Boeing MPD, which is an asked if the AOA sensors and MCAS are Error in Note 2 to Paragraph (i) of the operational check of the MCAS discrete in the MEL. The commenter stated that Proposed AD if the AOA and MCAS are essential, to verify the integrity of MCAS. The Comment summary: A4A stated that then they must be included in the MEL other new task is Item 22–030–00 in the note 2 to paragraph (i) of the proposed so that pilots cannot take off if the AOA Boeing MPD, which is also a CMR (22– AD incorrectly refers to MMEL item 22– sensor or the connection between the CMR–02) that operationally checks the 11–06–2B instead of MMEL item 22–11– AOA and MCAS is degraded or failed. stabilizer trim enable ground path and 06–02B. autopilot arm cutout switch. FAA response: The FAA infers that the commenter is asking that the AOA FAA response: The FAA concurs and has revised this note, now note 3 to 8 SAFO 20015 is available at https:// sensors and MCAS be excluded from the www.faa.gov/other_visit/aviation_industry/airline_ MMEL, meaning that the equipment paragraph (i) of this AD, to refer to operators/airline_safety/safo/all_safos/. must be operative for dispatch. On April MMEL item 22–11–06–02B.

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13. Comments Regarding Removal of and 121.537 also place responsibility for FAA response: The information Note in Item (4) Within Figure 10 to operational control with the operator requested by the commenters is in the Paragraph (i) of the Proposed AD and require operators to exercise AFM. In addition, the FAA has Comment summary: A4A stated that operational control through approved or confirmed that Boeing will include the the FAA should correct conflicts accepted procedures that lead to the safe information requested by the between the NPRM and policies dispatch and operation of a flight. commenter in the FCOM (which is not regarding MEL items pertaining to Operators may also provide additional mandated by this AD) after publication several aspects of the flight control reporting and/or data collection such as of this AD. system (FCS). A4A noted that figure 10 irregularity reports, Aviation Safety I. Comments Related to Pilot Training to paragraph (i) of the proposed AD Action Program reports, flight and the Use of Simulators for Pilot contains a note under item (4) stating operational quality assurance data, or Training that both FCCs must be operative to ad-hoc data collection from flight data The FAA received several comments dispatch. A4A explained that there are recorders or from aircraft to the NPRM docket related to pilot several FCC functions that will continue communicating and reporting system training and certification and the to have MMEL deferral relief, as (ACARS) as part of their operational qualification and use of simulators for specified in figure 10 to paragraph (i) of control system. 14 CFR 121.703 requires pilot training. The FAA appreciates this the proposed AD and Revision 2 of the reporting of emergency actions during input and, where appropriate, MMEL. A4A added that the item (4) flight, such as stick shaker activations. considered the information in other statement in figure 10 to paragraph (i) of The FAA has not changed this final rule related actions (e.g., finalizing the 737 the proposed AD (which states that regarding this issue. FSB Report). Although the comments speed trim function must be operative 2. Comments Regarding Consistency of are beyond the scope of this rule, the for dispatch), combined with the 737 MAX and 737 NG AFM Procedures FAA provides the following responses. deletion of the Speed Trim deferral allowance from Revision 2 of the Comment summary: The BALPA 1. Comments Regarding Simulator MMEL, provides a clear indication that questioned whether applicable Training Speed Trim must operate normally for procedure changes from the 737 MAX Comment summary: Several dispatch. For these reasons, A4A AFM would be applied to the Boeing commenters, including Flyers Rights, recommended that the note be removed. 737 NG AFM to avoid confusion if ALPA, and the Turkish DGCA, stated FAA response: The FAA has removed pilots serve in both the Boeing 737 MAX that the FAA must require simulator the note identified in the A4A comment. and the Boeing 737 NG. training for pilots operating the Boeing The intent of the note was to emphasize FAA response: The FAA expects 737 MAX including training on specific that FCC deactivation is no longer Boeing will update the eight non-normal areas.10 Two commenters also permitted; this deactivation was procedures included in this final rule in recommended that the FAA address associated with Speed Trim Function the Boeing 737 NG AFM. The FAA is perceived deficiencies in 737 MAX relief in previous MMEL revisions. This considering mandating these 737 NG simulators related to accurate deactivation came as part of a required AFM changes by a separate AD representations of the force required by maintenance procedure supported by rulemaking action. Additionally, the pilots to turn the pitch trim wheel Boeing in the Dispatch Deviation Guide new special emphasis areas 9 described manually. (DDG). The FAA acknowledges that the in section 9.2 of the 737 FSB Report, FAA response: As noted, this AD does note is unnecessary, and the revised also apply to the Boeing 737 NG. not mandate pilot training. However, MMEL itself addresses the condition Therefore, pilots serving in mixed fleet consistent with the results of the JOEB specified in the note. For these reasons, operations of the Boeing 737 MAX and operational evaluation and in the FAA has revised this AD to remove the Boeing 737 NG will have consistent accordance with 14 CFR 121.405(e), the the note that was under item (4) in procedures and training in both FAA is requiring air carriers to revise all figure 10 to paragraph (i) of the airplanes. The FAA has not changed Boeing 737 MAX training curricula to proposed AD. this final rule regarding this issue. include the special training as described in the 737 FSB Report. This special H. Suggestions for Crew Reporting and 3. Comments Regarding Flight Crew Crew Procedures training includes training on all of the Operations Manual Content areas identified by the commenters, 1. Comments Regarding Crew Reporting Comment summary: The Turkish including the use of manual stabilizer of Irregularities DGCA commented that a comprehensive trim in an FFS. The FAA has taken steps Comment summary: A commenter description of the flight director bias out to verify that, in accordance with 14 stated that a procedure should exist of view needed to be included ‘‘in CFR 60.11(d), flight simulation training mandating that every 737 MAX operator FCOM’’ (the FAA infers the commenter device (FSTD) sponsors have evaluated inform Boeing, the FAA, and local is referring to a Flight Crew Operations the manual stabilizer trim system for authorities when any stall warning Manual) to ensure pilots will proper control forces and travel on each activation, airspeed disagree alert, understand that manual flight is altitude disagree alert, or AOA disagree necessary. Another commenter stated 10 Commenters suggested the following areas be included in simulator training: Stall recovery, flight alert occurs in normal operation that the ‘‘MAX system’’ (which the FAA displays, what to do if the AOA disagree light (excluding test flights or readiness infers means MCAS) must be included illuminates, maneuvers with the AOA sensor failed, flights). in the pilot’s manual. training that mimics the forces needed by pilots, FAA response: For U.S. operators, 14 intricacies of the manual trim wheel and how to implement two-pilot intervention, autopilot CFR 121.563 requires the pilot in 9 737 FSB Report, paragraph 6.11, defines a disconnect and flight director bias out of view, command to ensure all mechanical ‘‘special emphasis area’’ as ‘‘A training requirement dependencies between MCAS and the other aircraft irregularities occurring during flight unique to the aircraft, based on a system, procedure, systems, and differences in behavior when MCAS time are entered into the maintenance or maneuver, which requires additional is operational versus when MCAS has failed. highlighting during training. It may also require Another commenter also noted that computer-based log of the airplane at the end of that additional training time, specialized FSTD, or training (CBT) should include the AOA disagree flight time. 14 CFR 121.533, 121.535, training equipment.’’ warning system and the instrument panel gauges.

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FAA-qualified Boeing 737 MAX FFS. If Regarding concerns about mixed member of this panel and the panel’s the forces do not meet the specified fleets, the FAA notes that the new work is anticipated to begin in early requirements of 14 CFR part 60, special emphasis areas described in 2021. The FAA will continue to Appendix A, the FSTD sponsor must section 9.2 of the 737 FSB Report also advocate for taking steps to address not allow use of the FFS to conduct apply to the Boeing 737 NG. Therefore, automation dependency, manual flight training on the manual stabilizer trim pilots serving in mixed fleet operations operations proficiency, and improving wheel. of the Boeing 737 MAX and the Boeing pilot management of automated systems The FAA recommends that 737 NG will have consistent training in globally. No change to this AD is commenters review the 737 FSB Report both airplanes. The FAA refers necessary based on these comments. commenters to the 737 FSB Report for and SAFO 20014, Boeing 737–8 and 4. Comments Regarding Inclusion of further information specific to this 737–9 Airplanes: Pilot Training and Low-Time Pilots in Operational issue. Flight Simulation Training Devices Evaluation (FSTDs) Updates for more information 3. Comments Regarding Manual Flying Comment summary: The UAE GCAA on air carrier pilot training requirements Proficiency for the MAX.11 stated the operational evaluation should Comment summary: Several include low-time pilots with a 2. Comments Regarding New Pilot Type commenters asserted that pilots have an commercial pilot license. Rating over-reliance on automation and need FAA response: As previously Comment summary: Some training on manual flying skills to described in the ‘‘Related Actions’’ commenters suggested that the FAA ensure proficiency. section, the FAA completed the establish a new type rating for the FAA response: Although these operational evaluation jointly with Boeing 737 MAX because, according to comments are not within the scope of EASA, ANAC, and TCCA in September the commenters, the 737 MAX behaves the proposed rule, the FAA notes that 2020. The operational evaluation of the differently than the Boeing 737 Next air carrier pilots are required to 737 MAX with the new MCAS included Generation (NG), and differences demonstrate and maintain proficiency pilots from multiple countries with training is not adequate to address the of manual flying skills.12 The FAA’s varying levels of experience, including changes in the 737 MAX from the commitment to ensuring manual flying a low-time pilot with a commercial pilot previous series. Commenters suggested proficiency is evident in its publication license. that a new type rating would ensure that of several advisory circulars (ACs) and J. Requests for Clarification 737 MAX pilots are properly trained SAFOs related to this topic.13 Several commenters sought additional especially in abnormal and emergency The FAA continues to emphasize information about operation and situations. The UAE GCAA raised proficiency in manual flying skills for behavior of certain systems on the 737 concerns regarding a mixed fleet air carrier pilots by requiring 737 MAX MAX. consisting of both the Boeing 737 MAX special pilot training that focuses on and the Boeing 737 NG, suggesting that manual trim operations, manual flight 1. Comments Regarding Various AOA the FAA needed to examine the impact during MCAS demonstration at high Thresholds angles of attack, and manual flight with of mixed fleet operations on crew Comment summary: Several an unreliable airspeed condition. The training. commenters asked questions regarding 737 MAX special training is described FAA response: The FAA establishes the different thresholds used by the new type ratings through an operational in Appendix 7 of the 737 FSB Report. In September 2019, the FAA FCC and MDS software when comparing evaluation of an aircraft conducted by a AOA values. They asserted that use of Flight Standardization Board. The same presented a working paper at the International Civil Aviation different thresholds and different process determines the differences computers should be eliminated. They training required for a variation of the Organization (ICAO) Assembly seeking the establishment of a new panel that were concerned that different thresholds aircraft type (e.g., a new series). For for the two monitors could cause each new series of Boeing Model 737 would address pilot training and automation dependency. This panel confusion. They noted that if the airplanes, the FAA conducted the difference in AOA values is between the described evaluation and determined would be an important step in understanding the scope of automation two thresholds, MCAS would be that the same pilot type rating applies disabled but the AOA DISAGREE to all Boeing Model 737 airplanes. The dependency globally and bring the international community together to annunciation would not take place. FAA finds that this evaluation process FAA response: The FAA provides the work towards accepted solutions that has properly determined that the Boeing following clarification. At lower speeds could reduce the variability in how the 737 type rating is appropriate for the (flaps extended), the acceptable issue is addressed by individual CAAs. 737 MAX. However, in accordance with difference between the left and right With broad support for establishing a 14 CFR 121.400(c)(5), differences AOA values is larger. MCAS operates panel at the Assembly, the ICAO Air training is required for air carrier pilots with flaps fully retracted (higher Navigation Commission approved the to serve on a new series of the Boeing airspeeds), where the acceptable establishment of a new Personnel 737. As outlined in the 737 FSB Report, difference is smaller. the differences training from the Boeing Training and Licensing Panel (PTLP) in Airplanes experience significantly 737 NG to the 737 MAX includes June 2020. The U.S. has been named a different sideslip conditions during low- ground and flight training on abnormal speed flight compared to high-speed 12 See 14 CFR 121.423, 121.424, 121.427, 121.441, and emergency situations. and part 121 Appendices E and F. flight, resulting in larger differences 13 See AC 120–109A, Stall Prevention and between left and right sensed AOA 11 The 737 FSB Report is available at https:// Recovery Training; AC 120–111, Upset Prevention values at low airspeed when compared fsims.faa.gov/PICResults.aspx?mode=Publication& and Recovery Training; AC 120–114, Pilot Training to high airspeed. It is therefore doctype=FSBReports; and SAFO 20014 is available and Checking (14 CFR part 121, subparts N and O, at https://www.faa.gov/other_visit/aviation_ including Appendices E and F); SAFO 13002 appropriate for MCAS, which operates industry/airline_operators/airline_safety/safo/all_ Manual Flight Operations; and SAFO 17007 Manual only at high airspeeds (with the flaps safos/ Flight Operations Proficiency. retracted), to have a smaller acceptable

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difference (tighter tolerance) than the position is more than a few degrees in FAA response: The INOP markers are AOA DISAGREE alert, which functions the opposite direction of the pending simply stickers that are covering one of throughout the flight envelope (low and stabilizer command. The exception the selectable positions of a dial on the high airspeeds). With this tighter occurs when there is an MCAS airplane electronic flight instrument system tolerance, MCAS will be disabled with nose-down command during high-AOA (EFIS) panel. After installation of the the smaller difference between AOA flight, when the pilot is typically software required by paragraph (j) of sensor inputs; thus, preventing pulling aft on the control column. this AD, a display setting that had been erroneous MCAS commands. No change During the short duration of an MCAS inoperative will be operative. Removal to this AD is necessary based on these activation, the physical and software of the INOP marker will allow the comments. column cutouts will be temporarily flightcrew to select and use the now 2. Comments Regarding MCAS bypassed to allow the MCAS command. operative display setting. No change to this AD has been made based on these Activation Prior to Stick Shaker 4. Comments Regarding Term Used in comments. Comment summary: Several NPRM for Wiring Change 7. Comments Regarding Boeing Model commenters stated that the thresholds Comment summary: A commenter 737 STS Failures for MCAS activation and for stick shaker suggested changing the description of activation should ensure that stick wiring associated with the horizontal Comment summary: Several shaker occurs after MCAS activation. stabilizer trim system. The NPRM commenters noted that the STS has FAA response: The AOA threshold described one of the wires as ‘‘arm’’ been on Boeing Model 737 airplanes associated with MCAS activation is less wiring, and the commenter suggested since the Boeing Model 737 Classic than the AOA threshold associated with that the wiring be referred to as ‘‘power’’ airplanes, implemented with a single stick shaker. Therefore, MCAS will wiring. FCC in control of the function. They activate prior to stick shaker. FAA response: The wiring stated that the STS has always been 3. Comments Regarding Function of nomenclature in the NPRM is consistent subject to the failure conditions that Column Cutout Switches with that of the service information drove MCAS to require a dual FCC Comment summary: Several required by paragraph (k) of this AD. No solution. They asserted that the STS has commenters stated that the NPRM did change has been made to this AD based not failed to date, but seems vulnerable not explain the hardware and software on this comment. to a future failure. They asked whether modifications that provide new there is a plan to address STS on prior 5. Comments Regarding Autopilot models, or if the unhindered aft column functionality for control column cutout. Engagement During Stick Shaker They stated that there are three cutout saves those airplanes from conditions of control column cutout: Comment summary: A commenter further hazards. Main electric stabilizer trim column asked whether the autopilot can be FAA response: These comments do cutout, FCC trim column cutout, and engaged with the stick shaker active. not pertain directly to the unsafe FCC trim software column cutout. They The commenter noted that flight data condition of the Boeing 737 MAX that asked that the FAA explain the recorder data from the ET302 flight this AD addresses, and therefore no significant modification on the control shows that the autopilot was engaged change to this AD is required based on column cutout as part of this AD. while the stick shaker was active. these comments. Relevant to these FAA response: The functionality of FAA response: Flightcrew training comments, however, the new FCC the column cutout switches is described informs pilots how to recover from a software installed on the 737 MAX in section 6 of the ‘‘Preliminary stall, which does not include includes a cross-FCC monitor that will Summary of the FAA’s Review of the engagement of the autopilot. In some detect and stop any erroneous FCC- 737 MAX,’’ dated August 3, 2020, which cases, the autopilot can be engaged or generated stabilizer commands, was included in the docket for this AD remain engaged while a single stick including STS/MCAS commands. at the time of publication of the NPRM. shaker is active. For example, an AOA Earlier Boeing 737 models (pre-MAX) At the base of the control column are sensor failure (e.g., ET302 flight) can include full-time column cutout column cutout switches. They inhibit cause persistent erroneous stick shaker switches, which effectively protect stabilizer trim commands if the control that would also affect airspeed and against an erroneous stabilizer trim column moves more than a few degrees altitude displayed to one of the pilots. command. The pilot stops, or cuts out, in a direction opposite to the trim The Airspeed Unreliable procedure the trim command by moving the command. For example, if the stabilizer required by paragraph (h) of this AD control column to oppose the trim command is in the airplane nose- directs flightcrews to disengage the uncommanded trim input. Because of down direction and the pilot pulls the autopilot, then later allows for autopilot this design difference between the 737 column aft to raise the nose of the engagement, but only after a reliable MAX and earlier versions of the Boeing airplane, then the column cutout airspeed indication has been Model 737, the FAA is not aware of any switches will inhibit the command to determined. No change has been made need to change earlier Boeing 737 the stabilizer. There are column cutout to this AD based on this comment. models in this respect. switches for commands initiated by the 6. Comments Regarding Retention of K. Changed Product Rule/Regulations pilot using the thumb switches on the INOP Markers Allowance control wheels, and for commands initiated by the FCC for autopilot and Comment summary: Several This section addresses comments speed trim commands. The new FCC commenters questioned why the FAA regarding how the FAA certificates new software installed as required by proposed to mandate removing ‘‘INOP’’ and derivative aircraft, the overall paragraph (g) of this AD includes a markers as part of paragraph (j) of the configuration of the 737 MAX, whether redundant software equivalent of the proposed AD. They suggested that the it is appropriate to include systems like physical switches that interrupt FCC INOP markers be retained as a backup MCAS on airplanes, and specific commands. An FCC will not make a or to draw the attention of the comments suggesting changes to crew stabilizer command if the column flightcrew. alerting and indication on the 737 MAX.

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1. Comments Regarding Certification of tendency. Redesign suggestions include on the MAX during FAA flight testing. Derivative Airplane Models the following: Reverting to using the old Regarding the suggestion to revise the Comment summary: Several engines, replacing the engines with elevator system, the FAA does not commenters, including the Families of smaller engines, redesigning the prescribe design, but rather assesses Ethiopian Airlines Flight 302 and nacelles so they do not generate lift, and proposed designs, and the FAA finds NATCA, did not consider it appropriate increasing the height of the airplane by the new MCAS meets FAA safety that FAA regulations allowed for 737 extending the landing gear. standards. FAA response: The FAA does not MAX airplanes to be certificated as prescribe particular designs, but rather 4. Comments Regarding Crew Alerting derivative airplanes of the older, assesses the regulatory compliance and System existing Boeing 737 Type Certificate. safety of designs proposed by an Comment summary: The Families of They highlighted that all Model 737 applicant. In this case, the FAA Ethiopian Airlines Flight 302 suggested airplanes are included on the same type certificated the configuration of the simplifying the Crew Alert System on certificate. They stated that FAA MAX with its current configuration of the 737 MAX so that flightcrews are not regulations related to this practice wing, engine, landing gear, nacelles, overwhelmed by multiple warning should be amended to disallow this. A etc., with MCAS as part of the design. systems. They asserted that due to commenter suggested that type Since the initial certification of the provisions of 14 CFR 21.101, the 737 certificates should expire. Some MAX, an unsafe condition was MAX does not fully comply with 14 commenters contended that FAA identified and is addressed by the CFR 25.1322 concerning flightcrew regulations allow for existing type actions mandated by this AD. The FAA alerts. They asserted that an FAA rule certificates of older designs to be has determined that the resultant (14 CFR 21.101) allows for determining modernized excessively to avoid configuration, which includes the new that it would be ‘‘impractical’’ to complying with new more restrictive MCAS, is compliant with the 14 CFR comply with later amendments of requirements. They stated that every part 25 regulatory requirements and is regulations because the anticipated variation needs to be thoroughly safe. safety benefits do not justify the costs reviewed as if it were new. They also necessary to comply with later stated that when certifying a derivative 3. Comments Regarding Inclusion of amendments. They asserted that the aircraft, standard improvements should MCAS Boeing 737 MAX does not fully comply be required, such as to include brake Comment summary: Several with 14 CFR 25.1322(b)(3), which temperature gauges, to make upgrades to commenters, including the Families of requires advisory alerts ‘‘for conditions the airspeed system, and to introduce Ethiopian Airlines Flight 302, stated that require flightcrew awareness and triple redundancy for critical systems. that MCAS should not be retained on may require subsequent flightcrew Lastly, they stated that the 737 MAX the airplane. Some asserted that FAA response’’; 14 CFR 25.1322(c)(2), which airplane needs to be recertified with a regulations do not (or, if they do, they mandates that warning and caution new type certificate. Specific to the 737 should not) allow for inclusion of a alerts ‘‘must provide timely attention- MAX, they cited the new, larger engines stability augmentation system like getting cues through at least two installed on the old airframe, the age of MCAS on an airplane. They stated the different senses by a combination of stabilizer trim system, and the flight airplane should be redesigned via an aural, visual, or tactile indications’’; and deck caution and warning system. aerodynamic configuration change, as 14 CFR 25.1322(d), which states that FAA response: The comments discussed previously, such that it is ‘‘the alert function must be designed to recommend broader reforms to 14 CFR stable without MCAS, instead of relying minimize the effects of false and 21.19 and 21.101 and associated on automation like MCAS to make it nuisance alerts.’’ guidance that address the criteria and stable. They stated that if MCAS is Separately, NATCA recommended process used by the FAA, and the other installed, it would be unacceptable for that all changes to the 737 MAX comply major civil aviation authorities, when the airplane to become unstable with with the flightcrew alerting assessing proposed changes to existing MCAS inoperative. They questioned requirements in 14 CFR 25.1302 products. These comments do not how much divergent pitch instability is amendment 25–137 and 25.1322 pertain specifically to correcting the permitted in commercial aircraft. They amendment 25–131. Specifically, unsafe condition addressed in this AD. stated MCAS should be replaced with NATCA contended that the exception to The corrective action mandated by this an elevator system solution to resolve a 14 CFR 25.1322(b)(2), (b)(3), (c)(2), AD addresses the identified unsafe column force issue. (d)(1), and (d)(2) granted by the FAA for condition. FAA response: The FAA does not the 737 MAX should not be granted for have a factual basis to mandate the cockpit changes that would be 2. Comments Regarding Configuration of removing MCAS from the airplane and implemented by the proposed AD. 737 MAX finds that the unsafe condition is Finally, another commenter suggested Comment summary: Several appropriately addressed by the conducting a holistic evaluation of flight commenters, including the Families of requirements of this AD. In addition, deck human factors and crew alerting, at Ethiopian Airlines Flight 302, Flyers FAA regulations 14 CFR 25.21, 25.671, least ensuring all alerts comply with Rights, and Aerospace Safety and and 25.672 provide for inclusion of regulations, and reevaluate the Security, Inc., expressed fundamental stability augmentation systems in exception to the crew alerting concerns with the configuration of the showing compliance to those standards. regulation, and to ideally require 737 MAX. They stated that the design Stability augmentation systems are installation of an engine indication and should be changed, and should not have common features included in the design crew alerting system (EICAS) on the 737 been certificated originally. They cited of modern transport category airplanes. MAX. the new, larger engines installed on the Subpart B of 14 CFR part 25 requires FAA response: The 737 MAX older airplane in a new location that is transport airplanes to have stable pitch complies with 14 CFR 25.1322, as forward and higher, and potential characteristics. The 737 MAX airplane specified in that airplane’s certification associated impacts to aerodynamics, is stable both with and without MCAS basis. The 737 MAX crew alerting weight and balance, and pitch-up operating. This has been demonstrated system is not substantially changed

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from the 737 NG crew alerting system, certification basis is the latest (as considered. BALPA stated that the MAX which has been shown through service commenters believe it should be), accidents were due to modifying aircraft history to be reliable and safe. The FAA whether MCAS complies, and whether with a commonality of design that has determined the existing certification MCAS would comply if it were installed precluded the need for a level of basis for the 737 MAX airplane is as part of a new airplane. The comments certification rigor that the modification appropriate for the design changes were associated with hazard deserved. BALPA cited the Kegworth necessary to correct the identified classifications of the software and of accident with B737 Engine Instrument unsafe condition. certain failures of MCAS, Speed Trim, System (EIS) change that did not The FAA lacks a factual basis to and the pitch trim systems. The necessitate a new type rating for EIS- require any changes (simplifying the commenters asserted that a single- equipped models. BALPA asserted that crew alerting system or converting to channel system cannot be upgraded to had line pilots been involved in EICAS) other than those proposed in the a dual-channel system via a software certification of that EIS and assessing its NPRM and mandated by this AD. The change only, and that a hardware efficiency in imparting information to unsafe condition associated with this change must also be required. Another the pilots, then a different outcome may AD is related to MCAS and how it commenter asked whether certification have occurred. contributed to pilot workload. The testing was done with MCAS failed. FAA’s response: The FAA confirms changes mandated by this AD Other commenters suggested specific that operational pilots were an integral effectively address the unsafe condition. flight test scenarios. part of the certification of the 737 MAX. This AD includes two changes related FAA response: The initial 737 MAX Several types of pilots were embedded to the crew alerting system. First, the certification and the recent certification in the certification process. The FAA MDS software change required by of changes to the 737 MAX used the 737 has flight test pilots from its Aircraft paragraph (j) of this AD implements the MAX certification basis as documented Certification Service and aviation safety AOA DISAGREE alert that was in the Type Certificate Data Sheet. In inspector pilots from the Flight certificated, but erroneously not some areas, the regulations in the Standards Service participate in various implemented, during the initial certification basis are at earlier parts of the certification process. certification of the 737 MAX. The other amendment levels, as allowed by 14 Additionally, the certification process change is implemented by the new FCC CFR 21.101. The new MCAS complies involves a cooperative effort from not software required by paragraph (g) of with those design standards, and just the FAA, but also the aircraft this AD, which changes the conditions addresses the unsafe condition manufacturers, who closely consult for which the existing SPEED TRIM identified in this AD. While certifying with their customers. The 737 MAX FAIL and STAB OUT OF TRIM lights the new MCAS, the FAA determined the procedures and training were evaluated are illuminated. No change to this AD hazard levels associated with potential by the FAA, EASA, ANAC, and TCCA, is necessary based on these comments. failure scenarios after thorough review, including evaluations by pilots from including failure scenarios assessed by foreign CAAs and airline pilots from 5. Comments Regarding Autothrottle FAA pilots. many different countries representing a Indication The new MCAS software was certified wide range of experience. Associated Comment summary: NATCA asked as Level A using Radio Technical with the actions required by this AD, the FAA to require design changes to Commission for Aeronautics, Inc. 737 MAX flightcrew procedures and the autothrottle indication to meet (RTCA) DO–178 ‘‘Software training have been updated and current certification regulations, which Considerations in Airborne Systems and evaluated by the FSB to ensure are 14 CFR 25.1329(k) at amendment Equipment Certification’’ as a means of flightcrews are provided information 25–119 and 25.1322. compliance, per Advisory Circular 20– about MCAS and that flightcrews will NATCA stated that the Autothrottle 115. Regarding the assertion that the be trained on the new system before Disconnect alert on the 737 MAX is a new MCAS software is insufficient and operating the 737 MAX. red flashing light with no aural that a hardware change is needed, the existing hardware on the 737 MAX 3. Comments Regarding Assessment of component, which does not meet the Flightcrew Response Times standard alert definitions in 14 CFR airplane includes two AOA sensors and Comment summary: The FAA 25.1322 and 25.1329(k). two FCCs; therefore, with only a received two comments, including one FAA response: This request is software change to the existing dual- from the Families of Ethiopian Airlines unrelated to the unsafe condition FCC and dual-AOA hardware Flight 302, expressing concern regarding addressed by this AD. There are no configuration, MCAS became a dual- what they described as unrealistic changes to the autothrottle associated channel system. In addition to the dual expectations for pilot response times with this AD. architecture, the new FCC software that implements MCAS includes integrity after failures. The commenters noted L. Certification Process monitoring and cross-FCC monitoring. that the flightcrew is a key part of the aircraft control system, and pilot 1. Comments Regarding Compliance and The flight test program included flights reaction and response used for Certification Rigor of MCAS with MCAS failures, and the FAA determined the set of test scenarios to be certification must be operationally Comment summary: Some sufficient for demonstrating compliance representative and scientifically commenters had several questions with applicable 14 CFR part 25 validated. A commenter stated that regarding the certification associated regulations. Boeing failed to examine sufficiently the with the new MCAS, including the basis hazard of repeated MCAS activation due for assessing the change, whether the 2. Comments Regarding Embedding to erroneously high AOA and failed to change complies with applicable Pilots in Certification Process consider properly the real-world pilot regulatory requirements, and the rigor Comment summary: Several reaction to flight deck effects during associated with the certification effort. commenters, including BALPA, these potential failures. The commenters questioned the suggested that pilots should be FAA response: The FAA agrees that aviation standards that the FAA used to embedded in the certification process pilot reaction and response used for certify MCAS, including whether the and that average airline pilots should be certification should be operationally

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representative and validated. The FAA M. Proposed AD Revisions and Data compliance methods that the utilized the findings and Requests manufacturer developed specific to the 737 MAX design changes. The Trade recommendations from the accident 1. Comments Regarding Clarification of Secrets Act (TSA) prohibits the FAA reports and auditing entities to drive a the Unsafe Condition closer evaluation of airmanship and and its employees from disclosing pilot response. This resulted in Comment summary: A commenter companies’ proprietary information. 18 extensive FAA design reviews and suggested the FAA clarify that the U.S.C. 1905. The information is likewise agency’s intent is to address the validations conducted in engineering protected from disclosure under following unsafe condition: ‘‘Failures Freedom of Information Act (FOIA) simulators and in-flight tests. With the that results in repeated nose-down trim original MCAS design, pilots had full Exemption 4, and would not be commands of the horizontal stabilizer, available to members of the public control authority over MCAS, but had to that if not addressed, could cause the through a FOIA request for public use the electric stabilizer trim switches, flightcrew to have difficulty controlling access. 5 U.S.C. 552(b)(4). and could disable the system using the the airplane, and lead to excessive nose- The FAA supports the public’s rights stabilizer trim cutout switches. The new down attitude, significant altitude loss, to be reasonably informed of the basis MCAS design eliminates the need for and possible impact with terrain.’’ for agency rulemaking. This does not, time-critical pilot actions beyond FAA response: The FAA’s description however, require putting interested normal pitch attitude control using the of the unsafe condition in this AD is members of the public in a position to column alone for any foreseeable accurate. The commenter’s proposed reconstruct for themselves the failures. The FAA evaluated possible description of the unsafe condition is underlying technical analyses that are failures, including AOA failures, during specific to the narrow accident based on proprietary data; rather, the all phases of flight under the most scenarios. However, the unsafe FAA has provided, as the law specifies, critical (i.e., takeoff and go-around) conditions and corrective actions ‘‘either the terms or substance of the phases of flight and conditions. All addressed by this AD encompass not proposed rule or a description of the associated flight deck effects were only those scenarios described by the subjects and issues involved.’’ 5 U.S.C. replicated, and the workload and effect commenter, but also other related 553. If the FAA were to disclose or force of each in combination was considered scenarios, to ensure they do not occur the disclosure of manufacturers’ in service. and validated. These evaluations were proprietary data, there is risk of a conducted using a wide range of FAA 2. Comments Requesting Additional chilling effect that would make U.S. aviation less safe. Manufacturers could test pilots, FAA operations pilots, Information become hesitant to provide the FAA training pilots, and domestic and Comment summary: The FAA with fulsome design and manufacturing international pilots of varying received a variety of requests for information that best supports the FAA experience. The evaluations were additional information from numerous in addressing potential unsafe monitored by human factors specialists commenters, including the Families of conditions, instead seeking to provide to validate pilot reactions to possible Ethiopian Airlines Flight 302 and the only a bare minimum of information failures of the new design. Turkish DGCA. These requests ranged required by 14 CFR 21.3 and 121.703. The changes to the 737 MAX required from general to specific. The most FAA analysts would have difficulty by this AD address the unsafe condition. broadly-worded included requests for obtaining needed technical data, or such Therefore, the FAA has not changed this ‘‘all’’ data used by the agency to make details could be slow in forthcoming final rule based on these comments. its findings and to propose this rule, and during what are sometimes very urgent for ‘‘technical details of the proposed analyses. 4. Comments Regarding Integrated fixes.’’ Slightly more tailored requests This particular NPRM was Review Including MCAS asked for all data that showed the accompanied by the service bulletins for airplane’s stall characteristics were safe. all of the design changes except for one, Comment summary: Flyers Rights Very specific requests also were made, and a nearly 100-page summary of commented that MCAS should be such as for the MCAS SSA including its technical information in the evaluated from an integrated whole- fault trees and failure modes and effects ‘‘Preliminary Summary of the FAA’s aircraft system perspective, and analyses (FMEAs), a full description of Review of the Boeing 737 MAX,’’ dated evaluated with the appropriate system input signals and functions, and August 3, 2020. This information fairly catastrophic failure designation. details of the in-depth reviews that a apprised the public of the issues under FAA response: The FAA evaluated commenter stated took place to establish consideration in this rulemaking and MCAS from an integrated whole-aircraft the acceptability of implementing enabled informed responses, as system perspective. During certification MCAS through tailplane movement. evidenced by the more than two hundred submitted comments, many of of the new MCAS, Boeing developed Another commenter asked for internal objections by FAA employees to the which were highly technical. and the FAA approved an integrated NPRM. For example, the FAA received thirty SSA that assessed systems that interface FAA response: In reviewing whether comments regarding the adequacy of with MCAS. The FAA also approved an a particular issue is an unsafe condition two AOA sensors on the 737 MAX, with analysis of single and multiple failures, that requires corrective action, the FAA many suggesting that three sensors are which considered comprehensive relies upon data provided by the necessary to address the unsafe impacts of single and multiple failures. manufacturer, including the condition. Some of these commenters The FAA concluded that for manufacturer’s contractors and provided detailed engineering rationale, certification of the new MCAS, Boeing suppliers, which they have designated which was possible based on generally applied the appropriate hazard category as proprietary. available knowledge of how AOA designations. The records submitted by the sensors work; their reliability; and manufacturer to show compliance with general principles on system design, FAA regulations consist of highly system architecture, and system safety technical data and proprietary analysis techniques. The information

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that the FAA supplied thus enabled the separation safety standards (14 CFR must be completed ‘‘before further public to provide thoughtful comments 25.1707). flight’’ (including the ORF in paragraph on the agency’s proposal. As another Regarding the commenter’s statement (m) of the proposed AD) to fully address example, regarding the new FCC about continuous trim runaway, the the NPRM referenced unsafe condition. software, the NPRM provided a detailed Runaway Stabilizer NNC required by A4A asked the FAA to clarify the explanation of how the new MCAS figure 3 to paragraph (h)(4) of this AD airworthiness of the aircraft prior to functions (as implemented by the new is the AFM procedure to be used ‘‘[i]f completing the ORF. FCC software), and how the FAA uncommanded stabilizer movement FAA Response: The FAA did not proposed that those functions would occurs continuously or in a manner not intend the reference to ‘‘before further address the unsafe condition. Also, in appropriate for flight conditions.’’ flight’’ in paragraph (m)(1) of this AD to the ‘‘Preliminary Summary of the FAA’s 4. Comments Regarding Operational include the ORF. Therefore, the FAA Review of the Boeing 737 MAX,’’ dated Readiness Flight has revised paragraph (m)(1) of this AD August 3, 2020, the FAA explained the to require the ORF to be completed safety standards that the agency applied Comment summary: Several ‘‘before any other flight.’’ The FAA finds commenters, including Air China, to the software, and how the agency that completion of the actions specified Ameco, and the UAE GCAA, had validated that the new software would in paragraphs (g) through (l) of this AD questions about the operational function as intended. Without the need is adequate to accomplish the ORF readiness flight required by paragraph for underlying detail such as the actual safely. Ferry flights are permitted prior (m)(1) of this AD. They did not think the MCAS software code, which could not to or after the ORF as stated in ‘‘Operational Readiness Flight’’ (ORF) is be interpreted unless it is installed in paragraph (n) of this AD. the airplane or simulator, the sufficiently defined in Boeing Special information that the FAA supplied Attention Service Bulletin 737–00– 6. Comments Regarding Warranty enabled meaningful comments on the 1028, July 20, 2020. They suggested that Coverage of Wiring Change Costs Boeing publish a separate flight test software’s functions and how those Comment summary: A commenter document for the 737 MAX ORF rather functions address the unsafe condition. asserted that the cost of the horizontal than the profile in the service bulletin. Regarding the request for internal stabilizer wiring change would be borne They asked whether an AMOC is objections by FAA employees to the by the operators, and suggested that the required if there is a deviation from the NPRM, this final rule represents the wiring change should be done at ORF requirements in this AD. They considered position of the FAA based Boeing’s expense. asked whether a subsequent ORF is on the totality of the agency’s work. required if a fault is identified during FAA response: Boeing Service Bulletin 737–27–1318, identified in the 3. Comments Regarding Inclusion of the ORF required by this AD. NPRM as the appropriate source of Wiring Change in Proposed AD FAA response: The requirements of the ORF are intentionally brief and service information for the horizontal Comment summary: Several concise and are specified in the service stabilizer wiring change, states that commenters noted that the proposed AD bulletin. The requirements are to warranty remedies are available for would mandate wiring separation; achieve flaps-up flight at or above airplanes in warranty as of March 6, however, it was not clear to the 20,000 feet above mean sea level (MSL). 2020. Although the NPRM provided all commenters how separating wiring If a flight achieves these two criteria, the costs, it also noted, ‘‘[a]ccording to the prevents the repeated nose-down trim ORF is completed. There are no specific manufacturer, some or all of the costs of commands that this AD is intended to test conditions or required maneuvers. this proposed AD may be covered under correct. The Boeing service information The requirement is written to allow warranty, thereby reducing the cost indicates that a short circuit between operators the flexibility to utilize their impact on affected operators.’’ No the ‘‘Arm,’’ one of the Control signal own typical procedures and flight change to this AD is necessary based on lines, and a 28 VDC source will cause profiles, provided they include flight this comment. a stabilizer trim runaway. A commenter with the flaps up, at or above 20,000 feet 7. Comments Regarding Change to AOA noted that a continuous trim runaway above MSL. The service bulletin Sensor System Test Costs command is a different scenario from includes a suggested flight profile, repeated nose-down trim commands, which an operator may choose to use. Comment summary: Based on new and stated that continuous trim The FAA does not anticipate the need data, Boeing clarified and updated the runaway should be addressed via an for AMOCs related to paragraph (m)(1) amount of time it will take to perform AFM procedure. While the commenter of this AD due to the brevity of the the AOA sensor system test: 10 work- agreed that future production aircraft requirement. hours instead of 40 work-hours. Boeing should incorporate this corrective If a fault is identified during the ORF, noted that Boeing Special Attention action, the commenter did not find that a subsequent ORF is not required by this Service Bulletin 737–00–1028, dated an AD mandating corrective action was AD; however, the operator should July 20, 2020 (the source of service warranted. resolve the discrepancy using standard information identified in the NPRM for FAA Response: As noted in the procedures, which may require a test this test), overstated the time required. NPRM, Boeing re-assessed the stabilizer flight. Paragraph (m)(2) of this AD Boeing subsequently re-evaluated the trim control system and identified areas requires resolving any mechanical time it takes to do the test and of non-compliance with applicable irregularities that occurred during the determined the 10-work-hour estimate regulations. The Boeing system safety ORF following the operator’s FAA- better reflects the actual time required to analysis for the stabilizer trim control approved maintenance or inspection do the AOA sensor system test. Boeing system assessed compliance of the program, as applicable. reported this update in Information revised system (with wires separated). Notice IN–737–00–1028–00–01. Boeing and the FAA determined that 5. Comments Regarding Necessity for FAA response: The FAA concurs with wire separation is needed on the Boeing Flight Permit this requested change to the work-hour Model 737 MAX to bring the airplanes Comment summary: A4A noted that estimate for the reasons provided by the into compliance with the FAA’s wire all Required for Compliance (RC) steps commenter, and has updated the ‘‘Costs

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of Compliance’’ section in this final rule with 14 CFR 25.1301 and because the ‘‘[f]inally, the checklist would be accordingly. flightcrew procedures mandated by this revised to add a reference item to AD now reference the presence of this manually trim the horizontal stabilizer N. Requests for Clarification of alert.’’ Boeing stated that this comment for pitch control, and note that a two- Preamble Statements is included to add clarity and avoid pilot effort may be used to correct an Various commenters requested confusion. The AOA DISAGREE alert is out-of-trim condition’’ to ‘‘[f]inally, the clarification of preamble statements. not relied upon to guide flightcrew checklist would be revised to add a 1. Comments Regarding Preamble action; it is one of several flight deck reference item to not reengage the Changes From Boeing indications that may alert the flightcrew autopilot or autothrottle, note that a of an unreliable airspeed event. Due to two-pilot effort may be used to correct Comment Summary: Request to those integrated flight deck effects, the an out-of-trim condition, and note that clarify purpose of AOA sensors: flightcrew should execute the un- reducing airspeeds will reduce the effort Regarding the Proposed Design Changes annunciated Airspeed Unreliable needed to manually trim the horizontal section, Boeing requested that the FAA procedure. stabilizer for pitch control.’’ Boeing change ‘‘[t]he updated FCC software Comment Summary: Request for stated that this comment is included to would also compare the inputs from the consistent terminology of non-normal add clarity and avoid confusion. The two sensors to detect a failed AOA procedures: Regarding the Proposed existing checklist directs the flightcrew sensor’’ to ‘‘[t]he updated FCC software Design Changes section, Boeing to manually trim the horizontal would also compare the inputs from the requested that the FAA change ‘‘[t]o stabilizer. The revised checklist directs two sensors to detect a disagreement facilitate the flightcrew’s ability to the flightcrew to not re-engage the between the AOA sensors.’’ Boeing recognize and respond to undesired autopilot or autothrottle and provides stated that this comment is intended to horizontal stabilizer movement and the enhanced guidance that reducing add clarity and enhance the effects of a potential AOA sensor failure, airspeeds reduces the effort needed to completeness of the information the FAA proposes to mandate revising manually trim. included in the NPRM. The software and adding certain operating procedures Comment Summary: Request to compares two AOA inputs to determine (checklists) of the AFM used by the clarify conditions for AOA Disagree if they agree, within an appropriate flightcrew for the 737 MAX’’ to ‘‘[t]o procedure: Regarding the Proposed range, and if the STS should be in an facilitate the flightcrew’s ability to Design Changes section, Boeing operative state. recognize and respond to undesired requested that the FAA change Comment Summary: Request to horizontal stabilizer movement and the ‘‘[t]herefore, this proposed checklist clarify conditions for multiple MCAS effects of a potential AOA sensor failure, would be used when there is an activations: Regarding the Proposed the FAA proposes to mandate revising indication, such as an AOA DISAGREE Design Changes section, Boeing and adding certain non-normal alert, that the airplane’s left and right requested that the FAA change ‘‘[a] procedures (checklists) of the AFM used AOA vanes disagree’’ to ‘‘[t]herefore, subsequent activation of MCAS would by the flightcrew for the 737 MAX.’’ this proposed checklist would be used be possible only after the airplane Boeing stated that this comment is when there is an AOA DISAGREE alert, returns to a low AOA state, below the intended to clarify and enhance which indicates that the airplane’s left threshold that would cause MCAS consistency in the way the NPRM refers and right AOA vanes disagree.’’ Boeing activation’’ to ‘‘[a] subsequent activation to procedures found in the AFM. The stated that this comment is included to of MCAS would be possible only after referenced procedures are technically add clarity and avoid confusion. The the airplane returns to a low AOA state, referred to as ‘‘non-normal procedures’’ current wording may be interpreted to below the threshold that would cause and the NPRM uses the ‘‘non-normal suggest that there are multiple reasons MCAS activation, and then increases procedure’’ terminology in the to use the AOA Disagree non-normal above the activation threshold.’’ Boeing subsequent sentences. This change procedure. However, the only reason the stated that this comment is intended to simply makes the terminology flightcrew would perform the AOA improve clarity and completeness, and consistent. Disagree procedure is if the AOA that the proposed language more fully Comment Summary: Request to DISAGREE alert is annunciated. describes the conditions under which clarify certain Quick Reference Comment Summary: Request to multiple MCAS activations could occur. Handbook (QRH) provisions: Regarding clarify conditions for certain checklist The airplane must return to a low AOA footnote 15, in the Background section, steps: Regarding the Proposed Design state, below the threshold that would Boeing requested that the FAA change Changes section, Boeing requested that cause MCAS activation, and then ‘‘[a]ll of the checklists that the FAA the FAA change ‘‘[t]he checklist would increase above the activation threshold. proposes to revise or add to the AFM are also provide additional steps for the Comment Summary: Request to already part of Boeing’s QRH, for the flightcrew to subsequently complete for clarify purpose of AOA DISAGREE alert: 737 MAX (except for the IAS Disagree the descent, approach, and landing Regarding the Proposed Design Changes checklist, which is new to both the AFM phases of flight’’ to ‘‘[i]f IAS DISAGREE section, Boeing requested that the FAA and the QRH)’’ to ‘‘[a]ll of the checklists is not shown, the checklist would also change ‘‘[w]hile the lack of an AOA that the FAA proposes to revise or add provide additional steps for the DISAGREE alert is not an unsafe to the AFM are already part of Boeing’s flightcrew to subsequently complete the condition itself, the FAA is proposing to Quick Reference Handbook, or QRH, for descent, approach, and landing phases mandate this software update to restore the 737 MAX.’’ Boeing stated that this of flight.’’ Boeing stated that this compliance with 14 CFR 25.1301 and comment provides clarification. The comment is intended to improve clarity. because the flightcrew procedures IAS DISAGREE non-normal checklist is The steps indicated are only executed mandated by this AD now rely on this not new to the QRH. by the crew if IAS DISAGREE is not alert to guide flightcrew action’’ to Comment Summary: Request to present. ‘‘[w]hile the lack of an AOA DISAGREE clarify revised Runaway Stabilizer FAA response: The FAA agrees with alert is not an unsafe condition itself, checklist: Regarding the Proposed the foregoing assertions and Boeing’s the FAA is proposing to mandate this Design Changes section, Boeing rationale for its proposed changes. software update to restore compliance requested that the FAA change However, because the proposed changes

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would not affect any requirement of this addressed installation issues identified allowing use of either version would AD, no change to this AD is necessary in Revision 1 of the service information enhance the completeness of the service based on this comment. that needed to be addressed to ensure information by providing up-to-date proper incorporation of the changes. information in Revision 1, as well as 2. Comments Regarding Credit for MEL A4A requested that the FAA also credit for the original issue. Provisions allow later FAA-approved revisions of FAA response: The FAA finds that the Comment summary: Air China and this service information. requested action would enhance the Ameco requested that the FAA revise FAA response: Boeing Special completeness of the service information, paragraph (i) of the proposed AD to state Attention Service Bulletin 737–27– and leaves the effectivity and required that the incorporation of FAA 737 MAX 1318, Revision 2, dated November 10, actions unchanged. Therefore the FAA MMEL Revision 2, dated April 10, 2020, 2020, was issued primarily to identify has revised paragraphs (c), (j), and (o) of into the operator’s existing MEL would the IDRs that were issued to ensure this AD accordingly. show compliance with the requirements proper incorporation of changes that of paragraph (i) of the proposed AD. The were made in accordance with Revision 5. Comments Regarding Service commenter also recommended revising 1 of the service information. As Information: Boeing Alert Requirements paragraph (o) of the proposed AD to previously explained in the ‘‘Differences Bulletin 737–22A1342 RB provide credit for the actions specified from the NPRM’’ section, the FAA is Comment summary: Paragraph (g) of in paragraph (i) of the proposed AD, if requiring Revision 2 for the actions the proposed AD would require Revision 2 of the MMEL was required by paragraph (k) of this AD. installing new FCC OPS software. incorporated into the operator’s existing The FAA further agrees to provide Although no specific compliance MEL before the effective date of the AD. credit for the original and Revision 1 of method was provided, the proposed AD FAA response: Since operators are not this service information, provided the referred to AMM 22–11–33 as a source required to have an MEL, the FAA referenced 14 IDRs have been of guidance for the service information. cannot revise paragraph (i) of this AD to incorporated. The FAA also finds that Ethiopian Airlines Group reported that directly require operators to incorporate incorporation of certain FAA-approved it was notified by Boeing of the release Revision 2 of the MMEL. Paragraph (i) Boeing IDRs is acceptable in lieu of the of relevant service information for this requires that an operator update their corresponding RC step identified in the software installation: Service Bulletin MEL if they want to use it. The FAA service information. The FAA has 737–22A1342. Ethiopian requested that agrees with the intent of the request for revised paragraphs (k) and (o) the FAA consider this service credit for incorporating Revision 2 of accordingly in this AD. The IDRs information as a method of compliance the MMEL before the effective date of identified in Revision 2 of the service for the proposed FCC OPS software. this AD. Paragraph (f) of this AD bulletin include an additional IDR that FAA response: The FAA has reviewed requires that operators ‘‘comply with was not identified in Boeing Multi- Boeing Alert Requirements Bulletin this AD . . . unless already done.’’ Operator Message MOM–MOM–20– 737–22A1342 RB, dated November 17, Therefore, in light of that provision, no 0608–01B(R3), dated November 3, 2020; 2020, and determined that it is an change to this AD is necessary regarding this AD therefore does not refer to the appropriate source of service these requests. MOM since it is incomplete. information for the FCC OPS software Regarding the request to allow use of installation. The FAA has revised 3. Comments Regarding Service later-approved service information, an paragraph (g) of this AD to add this Information: Boeing Special Attention AD may not refer to any document that service information as a method of Service Bulletin 737–27–1318 does not yet exist. To allow operators to compliance. Comment summary: Air China, use later revisions of the referenced 6. Comments Regarding Effects Ameco, Boeing, A4A, and the Ethiopian document (issued after publication of Contributing to Flightcrew Workload Airlines Group requested that paragraph the AD), either the FAA must revise the (k) of the proposed AD refer to revised AD to refer to specific later revisions, or Comment summary: The NPRM service information for the horizontal operators or the manufacturer must preamble stated that following the Lion stabilizer trim wire bundle routing request approval to use later revisions as Air Flight 610 accident, data from the change. (The NPRM referred to Boeing an AMOC for the AD. The FAA has flight data recorder indicated that a Special Attention Service Bulletin 737– therefore not changed this AD regarding single erroneously high-AOA sensor 27–1318, Revision 1, dated June 24, this issue. input to the flight control system while 2020, as the appropriate source of the flaps are retracted can cause service information for this action, and 4. Comments Regarding Service repeated airplane nose-down trim of the provided credit for Boeing Special Information: Boeing Special Attention horizontal stabilizer and multiple flight Attention Service Bulletin 737–27– Service Bulletin 737–31–1860 deck effects, including stall warning 1318, dated June 10, 2020.) Comment summary: Boeing requested activation, airspeed disagree alert, and The commenters requested credit for that the FAA refer to Boeing Special altitude disagree alert, and ‘‘may affect the prior accomplishment of previous Attention Service Bulletin 737–31– the flightcrew’s ability to accomplish revisions of this service information, if 1860, Revision 1, dated July 2, 2020, for continued safe flight and landing.’’ certain Installation Deviation Records installing/verifying MDS software and Boeing commented that these effects (IDRs) identified in Boeing MOM– removing INOP markers, as specified in instead should be characterized as MOM–20–0608–01B(R3), dated paragraph (j) of the proposed AD. (The ‘‘contributing factors to crew workload.’’ November 3, 2020, have been proposed AD referred to Boeing Special Boeing said that its comment was incorporated. Boeing stated that the Attention Service Bulletin 737–31– intended to provide a more specific FAA and Boeing reviewed the IDRs that 1860, dated June 12, 2020, as the description of the way in which stall were issued to operators and appropriate source of service warning activation, an airspeed disagree maintenance repair organizations that information for these actions, and also alert, and an altitude disagree alert may completed the actions specified in the source of the applicability affect the flightcrew. Boeing reported Revision 1 of the service information, information in paragraph (c) of the that it has shown, and the FAA has and determined that certain IDRs proposed AD.) Boeing stated that found, that the effects of stall warning

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activation and airspeed/altitude factual basis to mandate that this rulemaking. These include limiting the disagree alerts specifically affect airplane be permanently grounded. 737 MAX’s overwater operation; flightcrew workload, an important factor converting all 737 MAX airplanes to 2. Comments Regarding Assessment of that can affect continued safe flight and cargo airplanes; using the Boeing Model Other Users of AOA Data landing. Boeing added that flightcrew 757 instead; allowing passengers booked workload has been considered and Comment summary: Ethiopian on this airplane to change flights; accounted for in the development of the Airlines Group noted that the proposed thoroughly redesigning the airplane’s software update and non-normal AD stated that MCAS logic that was flight control surfaces; increasing engine procedures described in the NPRM. dependent on a single AOA sensor power rather than decreasing pitch; input will be changed to using two AOA FAA response: The referenced flight limiting airplane nose up and installing inputs. The commenter asked about deck effects can contribute to the an Alpha floor design used on Airbus other users of AOA data, either as a flightcrew workload, but the FAA finds airplanes; requiring certain data to be single input user or a dual input user, that the most adverse flight deck effect transmitted from the airplane mid-flight; and whether the FAA can confirm the in the Lion Air 610 accident was a flight requiring certain parameters to be change to MCAS to use two AOA inputs control problem that affected the recorded such as the status of manual does not affect other users requiring flightcrew’s ability to accomplish electric trim switches; constraining the only one AOA input. continued safe flight and landing. flight envelope using control laws or FAA response: During the mechanical means; and changing the Because the proposed changes would certification of the new MCAS, Boeing not affect any requirement of this AD, airplane’s configuration. Some and the FAA scrutinized all users of commenters also suggested that the FAA no change to this AD is necessary based AOA data and considered normal and on this comment. ask the U.S. Congress to increase the failure conditions. There is no effect on agency’s budget and contract out its O. Additional Comments Unrelated to other users of AOA data. Other users of functions. These proposed solutions are the Unsafe Condition AOA data are compliant and safe. unrelated to the corrective actions that were proposed in this rulemaking and 1. Comments Regarding Removal of 737 3. Comments Not Related to the Unsafe therefore will not be addressed here. MAX Airplanes From Service Condition Addressed by This AD The FAA received a variety of Comment summary: Multiple The FAA received a variety of general comments and suggestions, including commenters requested that the FAA comments and allegations related to the from the Families of Ethiopian Airlines prevent the 737 MAX from reentering competence, ethics, motives, and Flight 302, related to other airplane service. Some asked that the FAA do so resources of the agency, the models, and requests that the FAA by removing the 737 MAX from the manufacturer, and their component review the safety of those other Boeing 737 Type Certificate; others organizations such as the organization airplanes and future airplanes. The FAA requested that the FAA permanently designation authorization (ODA) and is applying lessons learned on the 737 prohibit the airplane’s operation. the FAA Boeing Aviation Safety MAX to current and future FAA Oversight Office. These comments came The commenters expressed concern certifications and continued operational from individuals and organizations that safety processes. However, these for the continued safety of Model 737 included the Families of Ethiopian MAX airplanes. Some of these comments are unrelated to the unsafe Airlines Flight 302, Aerospace Safety condition addressed by this AD for the commenters expressed concern about a and Security, Inc., Aerospace Safety 737 MAX, and therefore will not be design that they characterized as old, Research Institute, Inc., AFA–CWA, addressed here. unsafe, or unstable, with inferior Allied Pilots Association, BALPA, The FAA received a variety of systems and an undue reliance on Ethiopian Airlines Group, and Flyers comments, including from the Families electronics and automated systems. Rights. These comments are unrelated to of Ethiopian Airlines Flight 302 and the Some commenters questioned the effect the particular unsafe condition and Allied Pilots Association, related to the on pilot workload of complex corrective action, and therefore are not adequacy of the regulations that govern procedures and multiple checklists. addressed here. how the FAA processes applications, Other commenters contended that the The FAA also received a variety of such as 14 CFR part 21 and 21.101 in MAX certification process was tainted comments related to other potential particular, and the design standards in by a lack of transparency, reliance on safety issues on the 737 MAX. The 14 CFR part 25 such as 25.1309 and self-certification, a rush to complete subjects of these comments include the 25.1322, and how the FAA applies certification, and certification decisions airplane’s susceptibility to high them, such as in AC 21.101 and AC that prioritized profit, cost reduction, intensity radiated field, protection of the 25.1329. These comments included 13 and expedience over safety. airplane’s rudder cable, the reliability of requests from BALPA for regulatory and FAA response: The FAA finds that the the airplane’s auto speedbrake system, other oversight changes applicable to requirements set forth in this AD engine bonding issues, electronic flight future aircraft models by the FAA and appropriately address the unsafe bags, slat track assemblies, the other authorities. The FAA’s regulatory condition and that upon completion of airplane’s refueling system, the requirements are promulgated via the mandated requirements, the 737 auxiliary power unit (APU) fuel tank notice-and-comment rulemaking as MAX airplane meets FAA safety float switch, the Landing Attitude required by the Administrative standards. The FAA acknowledges all of Modifier, the airplane’s fly-by-wire Procedure Act (APA), and the public the commenters’ safety concerns, and spoiler system, and the possibility of can petition for rulemaking at https:// those concerns align with the FAA’s foreign object debris. These issues are www.faa.gov/regulations_policies/ mission of ensuring safety in air unrelated to the particular unsafe rulemaking/petition/. commerce. However, the FAA bases its condition that this AD addresses and The FAA received several comments, decisions on data, and because the therefore are not addressed here. including from the Families of corrective actions the FAA is mandating The FAA also received a variety of Ethiopian Airlines Flight 302, to appropriately address the identified comments related to proposed solutions improve its processes and oversight, unsafe condition, the FAA lacks a other than those proposed in this such as those for approving proposed

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designs, overseeing manufacturers Such comments are not being • Boeing Special Attention Service (including conducting audits), addressed. Bulletin 737–27–1318, Revision 2, dated overseeing the Boeing ODA and other Commenters asked how the design November 10, 2020, describes designees including ensuring freedom changes to correct this unsafe condition procedures for changing of the from undue pressure, and overseeing all would be distributed to and approved horizontal stabilizer trim wire routing aspects of airline operations including by the CAAs and implemented by installations. maintenance practices and repair operators worldwide. The FAA, as the • Boeing Special Attention Service facilities. The FAA appreciates and airworthiness authority for the State of Bulletin 737–00–1028, dated July 20, considers all such input; however, it is Design for these airplanes, is obligated 2020, describes procedures for an AOA outside the scope of this particular by ICAO Annex 8 to provide Mandatory sensor system test and an operational rulemaking. Continued Airworthiness Information to readiness flight. 14 The FAA received requests, including CAAs of other countries. The FAA This service information is reasonably from the Allied Pilots Association, will provide the AD to those authorities, available because the information is regarding how the FAA should treat and ICAO Annex 8 requires them to take posted in the docket and because the alternative methods of compliance, appropriate action in response. interested parties otherwise have access known as AMOCs. The FAA Therefore, the FAA expects that foreign to it through their normal course of acknowledges the commenters’ concern; civil aviation authorities will adopt business or by the means identified in similar requirements to those mandated however, it is premature for the FAA to the ADDRESSES section. limit or foreclose the methods by which by this AD, and that foreign operators an applicant can show compliance with would then comply with those Effective Date requirements. this AD. Section 553(d) of the APA (5 U.S.C.) The FAA also received requests that Conclusion generally requires publication of a rule the agency create additional data for The FAA reviewed the relevant data, not less than 30 days before its effective public review. These included a request considered the comments received, and date. However, section 553(d) for a comparative analysis of the determined that air safety and the authorizes agencies to make rules difference in stability and control public interest require adopting this AD effective in less than thirty days, upon between the subject airplane and other with the changes described previously, a finding of good cause. Due to the airplane models. They also included a and minor editorial changes. The FAA relationship between the Lion Air request for in-depth reviews to establish has determined that these minor accident on October 29, 2018, and the the acceptability of implementing changes: Ethiopian Airlines accident on March MCAS through tailplane movement. The • Are consistent with the intent that 10, 2019, the FAA issued an Emergency creation of such additional information was proposed in the NPRM for Order of Prohibition on March 13, 2019, is not necessary to find compliance with addressing the unsafe condition; and generally prohibiting the operation of FAA regulations, or to find that the • Do not add any additional burden 737 MAX airplanes subject to this AD. unsafe condition has been addressed. upon the public than was already This AD now identifies the unsafe The FAA also received a request from proposed in the NPRM. condition in the 737 MAX and the Families of Ethiopian Airlines Flight The FAA also determined that these mandates corrective actions to correct 302 to commission a new independent changes will not increase the economic the unsafe condition so that general review board to prepare findings. burden on any operator or increase the operations may resume. With the The FAA commissioned an scope of this AD. publication of this AD, the Emergency independent review board, called the Related Service Information Under 1 Order is no longer necessary. Technical Advisory Board (TAB). The CFR Part 51 Accordingly, the FAA is rescinding the TAB is an independent team of experts Emergency Order contemporaneously that evaluated the design of the new The FAA reviewed and approved the with publication of this final rule. These MCAS. The TAB included FAA following service information. actions create the opportunity for • Boeing Alert Requirements Bulletin certification specialists and chief operators to safely return the 737 MAX 737–22A1342 RB, dated November 17, scientific and technical advisors not to service, following a fleet-wide 2020, describes procedures for involved in the original 737 MAX grounding lasting over twenty months. installation of FCC OPS software on certification program, and subject matter Therefore, the FAA finds that good FCC A and FCC B, a software experts from the U.S. Air Force, the cause exists pursuant to 5 U.S.C. 553(d) installation verification, and corrective Volpe National Transportation Systems for making this amendment actions. immediately effective to provide relief Center, and the National Aeronautics • Boeing Special Attention Service from the grounding restriction as and Space Administration. The TAB Bulletin 737–31–1860, Revision 1, dated operators take the required actions to findings are summarized in the July 2, 2020, describes procedures for address the unsafe condition. ‘‘Summary of the FAA’s Review of the installation of MDS software, a software Boeing 737 MAX,’’ which is posted in installation verification and corrective Costs of Compliance Docket No. FAA–2020–0686. actions, and removal of certain INOP The FAA estimates that this AD The FAA also received comments that markers on the EFIS control panels. were out of scope for other reasons, affects 72 airplanes of U.S. registry. The such as doubting the technical ability of 14 https://www.icao.int/safety/airnavigation/ agency estimates the following costs to the public to comment on this proposal. Pages/nationality.aspx. comply with this AD:

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ESTIMATED COSTS

Cost on U.S. Action Labor cost Parts cost Cost per product operators

FCC OPS installation and verification .. 1 work-hour × $85 per hour = $85 ...... $0 ...... $85 ...... $6,120. AFM revisions ...... 1 work-hour × $85 per hour = $85 ...... $0 ...... $85 ...... $6,120. MDS installation and verification, INOP 1 work-hour × $85 per hour = $85 ...... $0 ...... $85 ...... $6,120. marker removal. Stabilizer wiring change ...... Up to 79 work-hours × $85 per hour = Up to $3,790 ...... Up to $10,505 ...... Up to $756,360. Up to $6,715. AOA sensor system test ...... 10 work-hours × $85 per hour = $850 $0 ...... $850 ...... $61,200.

The FAA has received no definitive Regulatory Findings (b) Affected ADs data that would enable the agency to The FAA has determined that this AD This AD replaces AD 2018–23–51, provide cost estimates for the will not have federalism implications Amendment 39–19512 (83 FR 62697, operational readiness flight specified in December 6, 2018; corrected December 11, under Executive Order 13132. This AD 2018 (83 FR 63561)) (‘‘AD 2018–23–51’’). this AD. will not have a substantial direct effect Operators that have a MEL and choose on the States, on the relationship (c) Applicability to dispatch an airplane with an between the national government and This AD applies to The Boeing Company inoperative flight control system the States, or on the distribution of Model 737–8 and 737–9 airplanes, affected by this AD would be required power and responsibilities among the certificated in any category, as identified in to incorporate certain provisions into Boeing Special Attention Service Bulletin various levels of government. 737–31–1860, Revision 1, dated July 2, 2020. the operator’s existing FAA-approved For the reasons discussed above, I MEL. The FAA has determined that certify that this AD: (d) Subject revising the operator’s existing FAA- (1) Is not a ‘‘significant regulatory Air Transport Association (ATA) of approved MEL takes an average of 90 action’’ under Executive Order 12866, America Code 22, Auto flight; 27, Flight work-hours per operator, although the (2) Will not affect intrastate aviation controls; and 31, Indicating/recording agency recognizes that this number may in Alaska, and systems. vary from operator to operator. Since (3) Will not have a significant (e) Unsafe Condition operators incorporate MEL changes for economic impact, positive or negative, their affected fleet(s), the FAA has This AD was prompted by the potential for on a substantial number of small entities a single erroneously high angle of attack determined that a per-operator estimate under the criteria of the Regulatory (AOA) sensor input received by the flight is more accurate than a per-airplane Flexibility Act. control system to result in repeated airplane estimate. Therefore, the FAA estimates nose-down trim of the horizontal stabilizer, the average total cost per operator to be List of Subjects in 14 CFR Part 39 which, in combination with multiple flight $7,650 (90 work-hours × $85 per work- deck effects, could affect the flightcrew’s Air transportation, Aircraft, Aviation hour). ability to accomplish continued safe flight safety, Incorporation by reference, and landing. According to the manufacturer, some Safety. or all of the costs of this AD may be (f) Compliance covered under warranty, thereby Adoption of the Amendment Comply with this AD within the reducing the cost impact on affected Accordingly, under the authority compliance times specified, unless already operators. delegated to me by the Administrator, done. Authority for This Rulemaking the FAA amends 14 CFR part 39 as (g) Installation/Verification of Flight Control follows: Computer (FCC) Operational Program Title 49 of the United States Code Software (OPS) specifies the FAA’s authority to issue PART 39—AIRWORTHINESS rules on aviation safety. Subtitle I, Before further flight, install FCC OPS DIRECTIVES software version P12.1.2, part number (P/N) Section 106, describes the authority of 2274–COL–AC2–26, or later-approved the FAA Administrator. Subtitle VII, ■ 1. The authority citation for part 39 software versions, on FCC A and FCC B, and Aviation Programs, describes in more continues to read as follows: do a software installation verification. During detail the scope of the Agency’s Authority: 49 U.S.C. 106(g), 40113, 44701. the installation verification, if the approved authority. software part number is not shown as being The FAA is issuing this rulemaking § 39.13 [Amended] installed on FCC A and FCC B, before further under the authority described in flight, do corrective actions until the ■ 2. The FAA amends § 39.13 by: approved software part number is installed Subtitle VII, Part A, Subpart III, Section ■ a. Removing Airworthiness Directive on FCC A and FCC B. Later-approved 44701, General requirements. Under (AD) 2018–23–51, Amendment 39– software versions are only those Boeing that section, Congress charges the FAA 19512 (83 FR 62697, December 6, 2018; software versions that are approved as a with promoting safe flight of civil corrected December 11, 2018 (83 FR replacement for the applicable software, and aircraft in air commerce by prescribing 63561)), and are approved as part of the type design by the FAA after the effective date of this AD. regulations for practices, methods, and ■ b. Adding the following new AD: procedures the Administrator finds Accomplishment of all applicable actions necessary for safety in air commerce. 2020–24–02 The Boeing Company: identified as ‘‘RC’’ (required for compliance) This regulation is within the scope of Amendment 39–21332; Docket No. in, and in accordance with, the FAA–2020–0686; Product Identifier Accomplishment Instructions of Boeing Alert that authority because it addresses an 2019–NM–035–AD. Requirements Bulletin 737–22A1342 RB, unsafe condition that is likely to exist or dated November 17, 2020, is acceptable for develop on products identified in this (a) Effective Date compliance with the requirements of this rulemaking action. This AD is effective November 20, 2020. paragraph.

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Note 1 to paragraph (g): Guidance for Boeing Alert Requirements Bulletin 737– (h)(2) through figure 9 to paragraph (h)(10) doing the installation and installation 22A1342 RB, dated November 17, 2020. into the existing AFM. verification of the FCC OPS software can be (1) In the Certificate Limitations and found in Boeing 737–7/8/8200/9/10 Aircraft (h) Airplane Flight Manual (AFM) Revisions Operating Procedures chapters, remove the Maintenance Manual (AMM), Section 22–11– Before further flight, revise the existing information identified as ‘‘Required by AD 33. AFM to include the changes specified in 2018–23–51.’’ Note 2 to paragraph (g): Guidance for paragraphs (h)(1) through (10) of this AD. (2) In the Operating Procedures chapter, accomplishing the actions required by Revising the existing AFM to include the revise the General paragraph to include the paragraph (g) can also be found in Boeing changes specified in paragraphs (h)(2) information in figure 1 to paragraph (h)(2) of Alert Service Bulletin 737–22A1342, dated through (10) of this AD may be done by this AD. November 17, 2020, which is referred to in inserting a copy of figure 1 to paragraph BILLING CODE 4910–13–P

(3) In the Operating Procedures chapter, paragraph with the information in figure 2 to replace the existing Airspeed Unreliable paragraph (h)(3) of this AD.

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(4) In the Operating Procedures chapter, paragraph with the information in figure 3 to replace the existing Runaway Stabilizer paragraph (h)(4) of this AD.

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(5) In the Operating Procedures chapter, Inoperative paragraph with the information replace the existing Stabilizer Trim in figure 4 to paragraph (h)(5) of this AD.

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(6) In the Operating Procedures chapter, add the information in figure 5 to paragraph (h)(6) of this AD.

(7) In the Operating Procedures chapter, add the information in figure 6 to paragraph (h)(7) of this AD.

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(8) In the Operating Procedures chapter, add the information in figure 7 to paragraph (h)(8) of this AD.

(9) In the Operating Procedures chapter, add the information in figure 8 to paragraph (h)(9) of this AD.

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(10) In the Operating Procedures chapter, add the information in figure 9 to paragraph (h)(10) of this AD.

(i) Minimum Equipment List (MEL) modified by this AD are inoperative, an Provisions for Inoperative Flight Control airplane may be operated (dispatched) only System Functions if the provisions specified in figure 10 to In the event that the airplane functions paragraph (i) of this AD are incorporated into associated with the flight control system as the operator’s existing FAA-approved MEL.

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Note 3 to paragraph (i): The MEL (l) AOA Sensor System Test to operate the airplane to a location where provisions specified in figure 10 to paragraph Before further flight, do all applicable the actions of this AD can be performed. (i) of this AD correspond to Master Minimum actions identified as ‘‘RC’’ for the ‘‘Angle of (o) Credit for Previous Actions Equipment List (MMEL) items 22–10–01B, Attack (AOA) Sensor System Test’’ specified 22–10–02, 22–10–03, 22–11–01, 22–11–02, in, and in accordance with, the (1) This paragraph provides credit for the 22–11–05–02B, 22–11–06–02B, 22–11–08– Accomplishment Instructions of Boeing actions specified in paragraph (j) of this AD, 01A, 22–11–08–01B, 22–11–10A, 22–11–10B, Special Attention Service Bulletin 737–00– if those actions were performed before the and 27–41–01, in the existing FAA-approved 1028, dated July 20, 2020. effective date of this AD using Boeing Special Boeing 737 MAX B–737–8/–9 MMEL, Attention Service Bulletin 737–31–1860, (m) Operational Readiness Flight Revision 2, dated April 10, 2020, which can dated June 12, 2020. be found on the Flight Standards Information (1) After accomplishment of all applicable (2) This paragraph provides credit for the Management System (FSIMS) website, required actions in paragraphs (g) through (l) actions specified in paragraph (k) of this AD, https://fsims.faa.gov/PICResults.aspx of this AD, do all applicable actions if those actions were performed before the ?mode=Publication&doctype=MME identified as ‘‘RC’’ for the ‘‘Operational effective date of this AD using Boeing Special LByModel. Readiness Flight’’ specified in, and in Attention Service Bulletin 737–27–1318, accordance with, the Accomplishment dated June 10, 2020, or Revision 1, dated (j) Installation/Verification of MAX Display Instructions of Boeing Special Attention June 24, 2020, provided the 14 Installation System (MDS) Software, Removal of INOP Service Bulletin 737–00–1028, dated July 20, Deviation Records (IDRs) identified in Markers 2020. The ‘‘Operational Readiness Flight’’ paragraph 1.D., ‘‘Description,’’ of Boeing required by this paragraph must be Before further flight, do all applicable Special Attention Service Bulletin 737–27– accomplished before any other flight. A actions identified as ‘‘RC’’ in, and in 1318, Revision 2, dated November 10, 2020, special flight permit is not required to have been incorporated on the airplane. accordance with, the Accomplishment accomplish the ‘‘Operational Readiness Accomplishment of FAA-approved Boeing Instructions of Boeing Special Attention Flight’’ required by this paragraph. IDRs not identified in paragraph 1.D., Service Bulletin 737–31–1860, Revision 1, (2) After the ‘‘Operational Readiness dated July 2, 2020. Flight’’ and before further flight, any ‘‘Description,’’ of Boeing Special Attention mechanical irregularities that occurred Service Bulletin 737–27–1318, Revision 2, (k) Horizontal Stabilizer Trim Wire Bundle dated November 10, 2020, before the effective Routing Change during the ‘‘Operational Readiness Flight’’ must be resolved following the operator’s date of this AD, is acceptable for compliance Before further flight, do all applicable FAA-approved maintenance or inspection with the corresponding RC steps specified in actions identified as ‘‘RC’’ in, and in program, as applicable. Special Attention Service Bulletin 737–27– accordance with, the Accomplishment 1318, Revision 1, dated June 10, 2020, Instructions of Boeing Special Attention (n) Special Flight Permits provided those IDRs reference Boeing Special Service Bulletin 737–27–1318, Revision 2, Special flight permits may be issued in Attention Service Bulletin 737–27–1318, dated November 10, 2020. accordance with 14 CFR 21.197 and 21.199 Revision 1, dated June 10, 2020.

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(p) Alternative Methods of Compliance (ii) Steps not labeled as RC may be (iii) Boeing Special Attention Service (AMOCs) deviated from using accepted methods in Bulletin 737–27–1318, Revision 2, dated (1) The Manager, Seattle ACO Branch, accordance with the operator’s maintenance November 10, 2020. FAA, has the authority to approve AMOCs or inspection program without obtaining (iv) Boeing Special Attention Service for this AD, if requested using the procedures approval of an AMOC, provided the RC steps, Bulletin 737–31–1860, Revision 1, dated July found in 14 CFR 39.19. In accordance with including substeps and identified figures, can 2, 2020. 14 CFR 39.19, send your request to your still be done as specified, and the airplane (3) For service information identified in principal inspector or responsible Flight can be put back in an airworthy condition. this AD, contact Boeing Commercial Airplanes, Attention: Contractual & Data Standards Office, as appropriate. If sending (q) Related Information information directly to the manager of the Services (C&DS), 2600 Westminster Blvd., certification office, send it to the attention of (1) For more information about this AD, MC 110–SK57, Seal Beach, CA 90740–5600; the person identified in paragraph (q)(1) of contact Ian Won, Manager, Seattle ACO telephone 562–797–1717; internet https:// this AD. Information may be emailed to: 9- Branch, FAA, 2200 South 216th St., Des www.myboeingfleet.com. [email protected]. Moines, WA 98198; phone and fax: 206–231– (4) You may view this service information (2) Before using any approved AMOC, 3500; email: 9-FAA-SACO-AD-Inquiry@ at the FAA, Airworthiness Products Section, notify your appropriate principal inspector, faa.gov. Operational Safety Branch, 2200 South 216th or lacking a principal inspector, the manager (2) Service information identified in this St., Des Moines, WA. For information on the of the responsible Flight Standards Office. AD that is not incorporated by reference is availability of this material at the FAA, call (3) AMOCs approved previously for AD available at the addresses specified in 206–231–3195. 2018–23–51 are not approved as AMOCs for paragraphs (r)(3) and (4) of this AD. (5) You may view this service information this AD. that is incorporated by reference at the (r) Material Incorporated by Reference (4) For service information that contains National Archives and Records steps that are labeled as RC, the provisions (1) The Director of the Federal Register Administration (NARA). For information on of paragraphs (p)(4)(i) and (ii) of this AD approved the incorporation by reference the availability of this material at NARA, apply. (IBR) of the service information listed in this email [email protected], or go to: https:// (i) The steps labeled as RC, including paragraph under 5 U.S.C. 552(a) and 1 CFR www.archives.gov/federal-register/cfr/ibr- substeps under an RC step and any figures part 51. locations.html. identified in an RC step, must be done to (2) You must use this service information Issued on November 18, 2020. comply with the AD. If a step or substep is as applicable to do the actions required by Lance T. Gant, labeled ‘‘RC Exempt,’’ then the RC this AD, unless the AD specifies otherwise. Director, Compliance & Airworthiness requirement is removed from that step or (i) Boeing Alert Requirements Bulletin Division, Aircraft Certification Service. substep. An AMOC is required for any 737–22A1342 RB, dated November 17, 2020. deviations to RC steps, including substeps (ii) Boeing Special Attention Service [FR Doc. 2020–25844 Filed 11–18–20; 4:15 pm] and identified figures. Bulletin 737–00–1028, dated July 20, 2020. BILLING CODE 4910–13–C

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