63561

Rules and Regulations Federal Register Vol. 64, No. 224

Monday, November 22, 1999

This section of the FEDERAL REGISTER for activation of the pneumatic SUPPLEMENTARY INFORMATION: A contains regulatory documents having general deicing boots. This amendment is proposal to amend part 39 of the Federal applicability and legal effect, most of which prompted by reports of inflight Aviation Regulations (14 CFR part 39) to are keyed to and codified in the Code of incidents and an accident that occurred include an airworthiness directive (AD) Federal Regulations, which is published under in where the airframe 50 titles pursuant to 44 U.S.C. 1510. that is applicable to certain Sabreliner pneumatic deicing boots were not Model NA–265–40, NA–265–60, NA– The Code of Federal Regulations is sold by activated. The actions specified by this 70, and, NA–265–80 series airplanes the Superintendent of Documents. Prices of AD are intended to ensure that was published in the Federal Register new books are listed in the first FEDERAL flightcrews activate the pneumatic wing on July 16, 1999 (64 FR 38358). That REGISTER issue of each week. and tail deicing boots at the first signs action proposed to require revising the of ice accumulation. This action will Airplane Flight Manual (AFM) to prevent reduced controllability of the DEPARTMENT OF TRANSPORTATION include requirements for activation of due to adverse aerodynamic the airframe pneumatic deicing boots. effects of ice adhering to the airplane Federal Aviation Administration prior to the first deicing cycle. Related Proposals 14 CFR Part 39 EFFECTIVE DATE: December 27, 1999. In addition to the proposed rule [Docket No. 99±NM±137±AD; Amendment ADDRESSES: Information pertaining to described previously, in June 1999, the 39±11292; AD 99±19±03] this rulemaking action may be examined FAA issued 18 other similar proposals RIN 2120±AA64 at the Federal Aviation Administration that address the subject unsafe (FAA), Transport Airplane Directorate, condition on various airplane models Airworthiness Directives; Sabreliner Rules Docket, 1601 Lind Avenue, SW., (see below for a listing of all 19 Model NA±265±40, NA±265±60, NA±70, Renton, Washington; or at the FAA, proposed rules). Those 18 proposals and, NA±265±80 Series Airplanes Small Airplane Directorate, Wichita also were published in the Federal Aircraft Certification Office, 1801 Register on July 16, 1999. (Docket 99– AGENCY: Federal Aviation Airport Road, Room 100, Mid-Continent NM–153–AD, for Fokker Model F–27 Administration, DOT. Airport, Wichita, Kansas. Mark 100, 200, 300, 400, 500, 600, and ACTION: Final rule. FOR FURTHER INFORMATION CONTACT: Tina 700 series airplanes, was also issued as SUMMARY: This amendment adopts a Miller, Engineer, Flight Test a supplemental notice of proposed new airworthiness directive (AD), Branch, ACE–117W, FAA, Small rulemaking, and published in the applicable to certain Sabreliner Model Airplane Directorate, Wichita Aircraft Federal Register on August 6, 1999.) NA–265–40, NA–265–60, NA–70, and Certification Office, 1801 Airport Road, This final rule contains the FAA’s NA–265–80 series airplanes, that Room 100, Mid-Continent Airport, responses to all relevant public requires revising the Airplane Flight Wichita, Kansas 67209; telephone (316) comments received for each of these Manual (AFM) to include requirements 946–4168; fax (316) 946–4407. proposed rules.

Federal Reg- Manufacturer airplane model Number ister citation

Cessna Aircraft Company Models 500, 550, and 560 Series Airplanes ...... 99±NM±136±AD 64 FR 38374 Sabreliner Corporation Models 40, 60, 70, and 80 Series Airplanes ...... 99±NM±137±AD 64 FR 38358 Gulfstream Aerospace Model G±159 Series Airplanes ...... 99±NM±138±AD 64 FR 38341 McDonnell Douglas Models DC±3 and DC±4 Series Airplanes ...... 99±NM±139±AD 64 FR 38325 Mitsubishi Heavy Industries Model YS±11 and YS±11A Series Airplanes ...... 99±NM±140±AD 64 FR 38371 Gulfstream American (Frakes Aviation) Model G±73 (Mallard) and G±73T Series Airplanes ...... 99±NM±141±AD 64 FR 38355 Lockheed, Models L±14 and L±18 Series Airplanes ...... 99±NM±142±AD 64 FR 38338 Fairchild Models F±27 and FH±227 Series Airplanes ...... 99±NM±143±AD 64 FR 38322 Aerospatiale Models ATR±42/ATR±72 Series ...... 99±NM±144±AD 64 FR 38368 Jetstream Model BAe ATP Airplanes ...... 99±NM±145±AD 64 FR 38351 Jetstream Model 4101 Airplanes ...... 99±NM±146±AD 64 FR 38335 British Aerospace Model HS 748 Series Airplanes ...... 99±NM±147±AD 64 FR 38319 Saab Model SF340A/SAAB 340B/SAAB 2000 Series Airplanes ...... 99±NM±148±AD 64 FR 38365 CASA Model C±212/CN±235 Series Airplanes ...... 99±NM±149±AD 64 FR 38348 Dornier Model 328±100 Series Airplanes ...... 99±NM±150±AD 64 FR 38332 Lockheed Model 1329±23 and 1329±25 (Lockheed Jetstar) Series Airplanes ...... 99±NM±151±AD 64 FR 38316 de Havilland Model DHC±7/DHC±8 Series Airplanes ...... 99±NM±152±AD 64 FR 38362 Fokker Model F±27 Mark 100/200/300/400/500/600/700/050 Series Airplanes ...... 99±NM±153±AD 64 FR 42870 Short Brothers Model SD3±30/SD3±60/SD3±SHERPA Airplanes ...... 99±NM±154±AD 64 FR 38329

Comments making of this amendment. Due 1. Support for the Rule consideration has been given to the Interested persons have been afforded following comments received. One commenter supports the an opportunity to participate in the proposed rule.

VerDate 29-OCT-99 11:34 Nov 19, 1999 Jkt 190000 PO 00000 Frm 00001 Fmt 4700 Sfmt 4700 E:\FR\FM\A22NO0.144 pfrm02 PsN: 22NOR1 63562 Federal Register / Vol. 64, No. 224 / Monday, November 22, 1999 / Rules and Regulations

2. Request To Withdraw the Proposal: moisture and a specific temperature are result in persistent ice accretions. No Unsafe Condition observed. As discussed in Comment #3 However, the proposed procedure will Several commenters request that the (following this response), at least two minimize the residual and intercycle ice proposal be withdrawn because no airplane manufacturers have issued accretions because the ice will be shed unsafe condition exists on certain AFM’s that contain procedures to when the minimum thickness or mass airplanes. One of these commenters activate the deicing boots at the first required for shedding is reached. The states that the FAA is merely sign of ice accumulation. The FAA is residual and intercycle ice accretion speculating that the proposed Airplane unaware of any ice bridging problems thickness resulting from this procedure Flight Manual (AFM) revision will associated with early operations of is less than the ice accretion thickness either the airfoil or engine pneumatic improve safety. Further, the commenter typically recommended prior to deicing boots. operation of the pneumatic deicing boot. contends that the FAA cannot In response to the commenter’s Adverse airplane flying qualities substantiate that the proposed AFM question regarding the FAA meeting its resulting from ice accretions typically revision will prevent ice bridging. This own standards, the FAA infers that the are affected by the thickness, shape, same commenter also asks if the FAA commenter is requesting the basis for texture, and location of the ice met its own standards by testing the the FAA’s determination that the accretion. proposed procedure on each of the proposed procedures are safe. Most At least two airplane manufacturers affected airplanes. aircraft certification programs have not have issued AFM’s that contain The FAA does not concur that no considered the reduced controllability procedures to activate the deicing boots unsafe condition exists. As discussed in of the aircraft due to adverse at the first sign of ice accumulation. the preamble of the proposed rule, the aerodynamic effects of ice adhering to Those two airplane models have FAA has reviewed the icing-related the pneumatic boots. The requirements different wing and design incident history of certain airplanes, of this AD (activation of the deicing boot characteristics and different deicing and has determined that icing incidents system at the first sign of ice formation boot configurations. Further, those two may have occurred because pneumatic anywhere on the aircraft, or upon airplane models represent a large deicing boots were not activated at the annunciation from an ice detector proportion of the airplane fleet first evidence of ice accretion. As a system, whichever occurs first, along equipped with pneumatic deicing boots. result, the handling qualities or the with the periodic cycling of the boots) The FAA has received no reports controllability of the airplane may have will minimize the ice accretions and indicating any adverse effects of been reduced due to the accumulated thereby reduce the adverse aerodynamic residual ice resulting from early ice. The FAA also discussed an accident effects. activation of the deicing boots for these that occurred as a result of the failure of airplane designs. the flightcrew to activate the wing and 3. Request To Withdraw the Proposal: In addition, a number of airplane tail pneumatic deicing boots. Possible Adverse Effects of Residual Ice models are equipped with deicing boot Although there may have been no Several commenters state that deicing systems that include automatic reported cases of incidents or accidents boots do the best job of shedding ice on operating modes, wherein the boots on a specific airplane model, the a single cycle, if ice is permitted to automatically cycle at specific time potential still exists for reduced accrete to 1⁄4 or 1⁄2 inch before activation intervals after being activated. This controllability of all airplanes equipped of the boots. One of these commenters automatic cycling has surely resulted in with pneumatic deicing boots due to further contends that the effect of operation of the boots with less than the adverse aerodynamic effects of ice continuous cycling in auto mode may recommended thickness of ice accreted. adhering to the airplane. This AD not produce a clean shed of ice on each The FAA has received no reports addresses this unsafe condition. activation, and that residual ice must be indicating any adverse effects resulting Further, ice bridging of deicing boots taken into consideration before any from the use of the automatic mode. was considered during development of revision to the AFM is required. the proposed rule. A broad Another commenter states that, 4. Request To Withdraw or Delay: representation of the aviation although operation in the continuous Develop More Data community was consulted, including mode upon first indication of ice Several commenters request that the airframe manufacturers, air carriers, accretion would eliminate the problem FAA delay issuance of the rule until airline pilot associations, airplane of identification of accretion, the more data are developed and reviewed. owner associations, deicing boot commenter is concerned that there Certain of these commenters also state manufacturers, and National would then be a potential for degraded that at the public meeting on icing Aeronautics and Space Administration performance due to residual ice. (February 2–4, 1999), the consensus was (NASA). Also, articles readily accessible The FAA does not concur that the that a uniform procedure cannot be by the general piloting community proposal should be withdrawn because adopted for all airplanes. That is, a solicited operational information of concerns over residual ice. Operation ‘‘blanket’’ proposal for numerous concerning ice bridging of deicing boots. of pneumatic deicing boots typically airplanes (regardless of design) is The FAA considers that the general results in persistent ice accretions on inappropriate without specific consensus of the aviation community is the boot surfaces, even when 1⁄4 to 1⁄2 consideration for the individual designs. that little or no evidence exists of ice inch of ice is allowed to accrete prior to Another one of these commenters points bridging of deicing boots with current activation of the boots. The persistent out that each airplane model is unique deicing boot designs, and ice that is not residual and inter-cycle ice accretions and that the operating instructions for shed after the initial boot cycle typically result in adverse aerodynamic the for one continues to increase in thickness and effects and degraded airplane flying airplane model may not be appropriate sheds during subsequent cycles. qualities. Activation of the wing and tail for another airplane model. That In addition, many airplanes equipped pneumatic deicing boots at the first sign commenter further adds that the with pneumatic deicing boots to protect of ice accretion, or at the annunciation airframe manufacturer is in the best the engine are operated when icing of an ice detector system and periodic position to determine appropriate conditions are present, i.e., visible operation of the deicing boots will also limitations.

VerDate 29-OCT-99 11:34 Nov 19, 1999 Jkt 190000 PO 00000 Frm 00002 Fmt 4700 Sfmt 4700 E:\FR\FM\A22NO0.145 pfrm02 PsN: 22NOR1 Federal Register / Vol. 64, No. 224 / Monday, November 22, 1999 / Rules and Regulations 63563

Another one of the commenters deficiencies with regard to handling and of descent. The deicing boots were requests that, if the proposal is not performance due to airframe accreted finally activated and control of the withdrawn, the issuance of any ice. In conclusion, the commenters state airplane was regained after a loss of rulemaking be delayed since certain that, in the absence of any evidence to 3,500 feet in altitude. The report language of the requirements of the AD suggest deficiencies regarding this identified causal factors of the incident is confusing. subject, they cannot support the intent which included rapid accumulation of The FAA does not concur that a delay of the rule. glaze ice that was not evident to the in issuing this action is appropriate. The The FAA acknowledges that an flightcrew, difficulty of the flightcrew to FAA concurs that the airframe airplane model may have design visually gauge the ice accretion manufacturers present at the February characteristics that mitigate the adverse thickness on the wing’s , public meeting did not support a airplane flying qualities resulting from and propeller vibrations that disguised common procedure for the operation of ice accretion on deicing boot surfaces. the onset of wing stall. Even though this deicing boots. However, as mentioned As discussed in the proposal for this incident occurred outside of the United previously, there have been no adverse AD, the FAA has previously requested States, and although this airplane model reports on the airplane fleet equipped that interested persons provide demonstrated acceptable in-flight icing with pneumatic deicing boots that information on icing system design and airworthiness relative to FAA and Joint operate the boots at the first sign of ice operations procedures concerning flight Airworthiness Authorities (JAA) accretion. With the exception of ‘‘older’’ during icing conditions. The request requirements, the incident illustrates pneumatic boots (reference comment #7, also asked manufacturers, who are in the vulnerability of this airplane model below), the FAA finds that a common the best position to determine those to the safety condition addressed by this procedure for boot operation is operating procedures, to provide data AD. appropriate. The FAA has determined showing that their aircraft have safe One commenter, British Aerospace, that the common procedures for operating characteristics with ice has requested until October 20, 1999, to operation of deicing boots as required accreted on the protected surfaces provide additional data to substantiate by this AD (activation of the deicing (boots). That information was requested that the Model ATP airplanes and boot system at the first sign of ice specifically by letter on October 1, 1998, Model HS 748 airplanes can safely formation anywhere on the aircraft, or to certain manufacturers of airplanes operate with ice accumulations on the upon annunciation of an ice detector certified in accordance with part 25 of protected surfaces. As discussed system, whichever occurs first, and the Federal Aviation Regulations (14 previously and in the NPRM, the FAA periodic cycling of the boots) will CFR part 25). Except as discussed in considers that this same vulnerability minimize the ice accretions and thereby Item 6 of the comment section of this exists on all airplanes equipped with reduce the adverse aerodynamic effects. final rule, no other information received pneumatic deicing boots. To withdraw or delay this AD would caused the FAA to reconsider that an In the interest of safety, the FAA finds be inappropriate since the FAA has unsafe condition may exist, or that a that it is not prudent to delay issuance determined that an unsafe condition revision of the AFM, such as required of the final rules on those airplane exists, and that the required AFM by this AD, was unsafe for those models. However, British Aerospace revision must be accomplished to airplanes. and any other manufacturer is ensure continued safety of the fleet. The Additionally, similar information was encouraged to request approval of an fact that other data may be developed at specifically requested in the discussion alternative method of compliance with a later time does not negate the FAA’s section of the proposed rule. Of the the airworthiness directive based on responsibility to address the existing comments to the proposal that were substantiating data indicating that a identified unsafe condition in a timely received by the FAA, no additional data particular aircraft can safely be operated manner. No change is necessary to the was included for Dornier Model 328– with the ice that would accumulate on final rule in this regard. 100 series airplanes, or de Havilland the protected surfaces prior to activation The FAA is unable to respond to one Model DHC–7/DHC–8 series airplanes of the ice protection system. commenter’s statement that certain that caused the FAA to reconsider the language of the proposal was confusing previous conclusion that an unsafe 6. Request To Withdraw the Proposal for since no example was specified. condition exists. Further, no data was Certain Other Airplanes provided to indicate that the proposal to Two manufacturers request that the 5. Request To Withdraw Proposals for require activation of wing and tail proposals regarding Cessna Model 500, Certain Airplanes pneumatic deicing boots at the first sign 501, 550, 551, and 560 series airplanes, Three commenters, all airframe of ice accretion or annunciation of an and British Aerospace (Jetstream) Model manufacturers, request that the proposal ice detector system was unsafe for any 4101 airplanes be withdrawn. The be withdrawn for several airplane particular airplane model. manufacturers advise that the testing models [British Aerospace Model ATP United Kingdom Accident summarized in their comments provides airplanes, British Aerospace Model HS Investigation Board Preliminary Report evidence that the current procedures 748 airplanes, Dornier Model 328–100 EWC 91/18 indicated that, while on provide a safe method to operate those series airplanes, and deHavilland Model climb to 16,000 feet in the vicinity of airplane models. The manufacturers DHC–7/DHC–8 series airplanes] since Oxford, England, on August 11, 1991, a conclude that, based on the service they have been certified to be in British Aerospace Model ATP airplane history and data provided to the FAA, compliance with part 25 of the Federal suffered a significant degradation of the proposed AFM revision for those Aviation Regulations (14 CFR 25.1419). flying qualities and propeller icing. models is unnecessary. Additionally, the commenters point out According to that report, the deicing The FAA concurs that the notice of that those airplanes have been boots of the airplane were not activated, proposed rulemaking for Cessna Model certificated in accordance with the and the airplane stalled, experienced 500, 501, 550, 551, and 560 series appropriate foreign civil airworthiness severe uncontrolled roll oscillations, airplanes should be withdrawn based on authorities. The commenters further severe vibration that rendered the the following information. The explain that service experience of those electronic flight instruments partially manufacturer performed a complete airplanes does not indicate any unreadable, and developed a high rate evaluation of the stall and handling

VerDate 29-OCT-99 11:34 Nov 19, 1999 Jkt 190000 PO 00000 Frm 00003 Fmt 4700 Sfmt 4700 E:\FR\FM\A22NO0.145 pfrm02 PsN: 22NOR1 63564 Federal Register / Vol. 64, No. 224 / Monday, November 22, 1999 / Rules and Regulations characteristics with simulated ice airplanes, the Model 500 series icing and safe flight speeds (minimum shapes on the Model 550 (Bravo) series airplanes also satisfactorily addresss the operating speeds) established airplanes. Stall speeds and warning unsafe condition addressed by this AD. accordingly. Affected AFM performance margins were evaluated with a 1⁄2-inch The FAA also notes that testing of information was derived for icing glaze ice shape and with an ice shape Model 560 series airplanes revealed conditions based on the higher associated with the system failure. This problems in the stall warning margin for operating speeds, in accordance with 1⁄2-inch ice shape simulated the ice flight in icing conditions that were JAA draft AMJ25.1419. shape prior to deicing boot activation. addressed by previously issued The Cessna and British Aerospace Maneuver margin testing consisted of airworthiness directives. aircraft models discussed in this left and right 40-degree bank turns. Stall The FAA also concurs that the notice comment have been tested and, where characteristics were evaluated with a 1⁄2- of proposed rulemaking for British appropriate, changes have been made to inch rime ice shape configuration. Stall Aerospace Jetstream Model 4101 ensure the airplanes are safe for characteristic testing consisted of wings airplanes should be withdrawn based on operations with ice accretions on the level and 30-degree bank turns. At the the following information. In response protected surfaces. Without this type of conclusion of the testing it was to the FAA’s October 1, 1998, letter testing and substantiation, the FAA determined that the airplane had an (discussed previously), British must conclude the aircraft affected by acceptable stall warning margin with ice Aerospace submitted a summary of the this final rule may be subject to adverse shapes present. The manufacturer handling and performance flight test aerodynamic effects due to ice maintains that Model 500/501, Model results that were produced during the accretions on the protected surfaces 550/551, and Model 550 (Bravo) series original flight in icing certification. This prior to deicing boot operation. Other airplanes all use a common wing airfoil summary was referenced in their manufacturers may also develop the with some minor differences in span response to the proposed rulemaking. necessary data to substantiate that their and wing loading. These aircraft also The commenter volunteered to provide airplanes are safe with these accretions use a common tail configuration (airfoil, any reports referenced in the summary. and request approval of an alternative span, and leading edge sweep). The FAA requested and subsequently method of compliance. Additionally, the FAA reviewed the received copies of the full handling and 7. Request To Differentiate Between Type Inspection Report (TIR) for Model performance flight test results for ‘‘Modern’’ Boot Systems and ‘‘Older’’ 550 (Bravo) series airplane testing and certification in the icing conditions Boot Systems found that ice shapes were placed on specified in Appendix C of part 25 of both the protected and unprotected the Federal Aviation Regulations (14 Several commenters request that the surfaces. CFR 25), and the JAA draft issue of difference between the ‘‘older’’ boot The Model 560 (Ultra) series airplanes AMJ25.1419, which was used as systems and the ‘‘modern’’ boot systems underwent an extensive ice shape stall guidance for compliance with JAR/FAR be explained. These commenters investigation. This investigation 25.1419. The FAA reviewed these express concern that although both consisted of stall testing of the baseline reports and guidance material and finds systems are addressed in the proposal, airplane and the airplane with the most that the Jetstream 4101 airplane was there may not be a sound technical adverse simulated intercycle ice shapes. adequately tested with a variety of reason to apply the requirements of the The ice shapes consisted of 1⁄2-inch natural ice accretions on both the proposal to both types of boot systems. shapes on the surfaces protected by protected and unprotected surfaces. The FAA acknowledges that boots and 3-inch shapes on unprotected Handling and performance flight test definitions of ‘‘older’’ and ‘‘modern’’ flight surfaces. The stall speeds was accomplished for the following: pneumatic boot systems should be determined by this testing were Normal Operation of the Deicing Boots, provided. Therefore, for the purposes of incorporated into the Safeflight Angle of 1⁄2-to 3⁄4-inch of ice on the protected this AD, ‘‘modern’’ pneumatic boot Attack computer to increase the stall wing leading edges and up to 3 inches systems may be characterized by short warning margin during flight in icing of ice on unprotected leading edges; segmented, small diameter tubes, which conditions. The Model 560 series Simulated Failure of the Deicing Boots, are operated at relatively high pressures airplanes angle of attack computer was approximately 1 to 11⁄2 inches of ice on [18–23 pounds per square inch (psi)] by also updated to incorporate a normal all leading edges; Ice Accreted During excess that is provided by mode and an ice mode stall warning the Take-off Phase, a thin rough layer of turbine engines. ‘‘Older’’ pneumatic system. The changes to the angle of ice accreted during the initial take-off boot systems may be characterized by attack computer on Model 560 and 560 phase to 400 feet, prior to operation of long, uninterrupted, large diameter (Ultra) series airplanes were proposed deicing boots. tubes, which were operated at low by Rules Docket No. 98–NM–312–AD. These ice accretion depths were pressures by engine driven pneumatic The FAA notes that extensive testing established to address the following: Ice pumps whose pressure varied with of Model 550 and 560 series airplanes accreted during the rest-time of a engine revolutions per minute (rpm). (in which acceptable stall protection deicing cycle, delayed operation or This low pressure coupled with long and maneuver margins at operational failure of the system, and residual ice and large diameter tubes caused early speeds were demonstrated with accumulations. The flight testing de-ice systems to have very lengthy expected ice accretion on the deicing examined stall speeds, stall warning inflation and deflation cycles and dwell boot surfaces) indicates that these margins, stall characteristics, maneuver times. (Dwell time is the period of time airplanes can safely operate with ice margins, longitudinal controllability, that the boot remains fully expanded accretions associated with the AFM configuration changes, ability to following the completion of the normal operations procedures of the trim, susceptibility to stall, inflation cycle until the beginning of the deicing boots. These attributes and longitudinal, lateral, and directional deflation cycle.) demonstrate that Model 550 and 560 stability. The angles of attack for series airplanes satisfactorily address activation of the stall warning system 8. Request To Withdraw the Proposal the unsafe condition addressed by this and stall identification system (i.e., stick For Airplanes with ‘‘Older’’ Boots AD. Since Model 500 series airplanes shaker or ) are reset to lower Two commenters request that the are similar to Model 550 series values (i.e., higher speeds) for flight in proposed rules applying to Gulfstream

VerDate 29-OCT-99 11:34 Nov 19, 1999 Jkt 190000 PO 00000 Frm 00004 Fmt 4700 Sfmt 4700 E:\FR\FM\A22NO0.146 pfrm02 PsN: 22NOR1 Federal Register / Vol. 64, No. 224 / Monday, November 22, 1999 / Rules and Regulations 63565

Model G–159 series airplanes and Rulemaking Advisory Committee airplanes. This would allow the AFM to McDonnell Douglas Model DC–3 and (ARAC) Ice Protection Harmonization clearly indicate to the flightcrew when DC–4 series airplanes be withdrawn. Working Group (IPHWG) completed a the deicing boots should be deactivated, Both commenters state that those comprehensive review of past icing rather than necessitating that the airplane models do not meet the accidents/incidents. The IPHWG flightcrew first determine if there are common definition of the word concluded that the only phases of flight other portions of the AFM that indicate ‘‘modern.’’ (See Comment #7 of this that demonstrate a safety concern are that the deicing boots should not be final rule for a definition of ‘‘modern’’ holding patterns and various approach used during specific phases of flight. as used in this AD.) One commenter segments; since these operations are Therefore, the FAA encourages requests states that the current AFM specifically conducted at lower airplane speed, for approval of alternative methods of directs the flightcrew to wait for 1⁄4-inch instability could occur as a result of ice compliance to customize the AFM of ice before activating the boots. accumulations on the wing and tail limitation to the specific airplane Further, the commenter asserts that the surfaces. model. current procedure was developed The FAA does not concur that the However, the FAA does not concur during certification and is the basis for AFM revision should be limited to the with the request to revise the final rule the airplane’s approval for flight into holding and approach phases of flight. that applies to Saab Model SAAB known icing. Additionally, the The FAA acknowledges that the IPHWG SF340A/SAAB340B/SAAB 2000 series commenters assert that the in-service is working on a proposed operations airplanes since the existing Saab AFM safety records for more than 40 years rule that may only be applicable during does not indicate that the deicing boots indicates that the existing procedures holding and approach phases of flight. should not be used during take-off and are appropriate for these airplanes. The However, the IPHWG continues to work landing. If the commenter has data to commenter concludes that the proposed on the proposed rule and has not indicate that the deicing boots should AFM revision is in direct opposition to reached technical agreement. Since not be used during those phases of the certification findings. discussions are ongoing, it would not be flight, the commenter should take action The FAA acknowledges that early appropriate to assume that the IPHWG to revise the AFM and request approval activation of the ‘‘older’’ pneumatic positions as presented by the of an alternative method of compliance. deicing boots may create the hazard of commenter will necessarily be reflected 10. Request To Revise Instructions on ice bridging on the ‘‘older’’ systems. As in the actual published proposal. When To Deactivate the Boot System discussed in Comment #2 previously, Another commenter, an airplane ‘‘older’’ boots may be susceptible to ice manufacturer, stated that the AFM for One commenter requests that two bridging, and the FAA concurs that Model SF340A/SAAB340B/SAAB 2000 changes be made to paragraph (a) of the requiring the activation of the boots at series airplanes currently does not limit proposal. The first change would be to the first sign of icing may actually the operation of the deicing boots specify that the wing and tail leading introduce an unsafe condition on those during specific phases of flight. The edge pneumatic deicing boot system airplanes. In order to address this issue, commenter requests that the AFM may be deactivated only after the FAA is taking the following steps. change required by paragraph (a) of the completion of an entire deicing cycle First, to accommodate certain airplane proposal be revised to limit the after leaving icing conditions. The models of the fleet (i.e., Gulfstream applicable phases of flight where the commenter also requests that the Model G–159 series airplanes and AFM specifies that deicing boots should proposal be revised to add related McDonnell Douglas Model DC–3 and not be used. Specifically, the procedures for operating speeds, and DC–4 series airplanes) that may be commenter requests that the language be that related procedures for operation of equipped with the ‘‘older’’ pneumatic revised to read ‘‘Deicing boots must not the (if any) be discontinued deicing boot system, the FAA is be used during take-off and landing.’’ only after the airplane is determined to considering the issuance of The FAA partially concurs, and be clear of ice. The commenter states supplemental NPRM’s for those airplane acknowledges that clarification is that natural ice shedding, melting, or models. The purpose of the necessary. It was the FAA’s intent that sublimation from the protected areas supplemental NPRM’s would be to the boots do not have to be operated at will mostly eliminate residual ice. require an inspection to determine the first sign of ice accretion during Regarding the commenter’s first which type of pneumatic deicing boots those phases of flight if there are request, the FAA concurs. For the are installed on the airplanes, and to existing procedures in the AFM that reasons the commenter stated, the FAA require operation of the boots at the first prohibit the operation of the boots has revised paragraph (a) of the final sign of ice accretion if the airplanes during specific phases of flight. rule from: ‘‘The wing and tail leading have been retrofitted with ‘‘modern’’ However, the boots must always be edge pneumatic deicing boot system boots. Second, for aircraft with ‘‘older’’ operated at the first sign of ice accretion may be deactivated only after leaving pneumatic boots installed, the FAA will if, in accordance with the AFM, it is icing conditions and after the airplane is continue to investigate other solutions acceptable to operate the boots during determined to be clear of ice;’’ to ‘‘The to the unsafe condition of reduced all phases of flight. Therefore, the FAA wing and tail leading edge pneumatic handling qualities or controllability of has revised paragraph (a) of the final deicing boot system may be deactivated the airplane due to ice accumulations rule to state, ‘‘Except if the AFM only after completion of an entire on the protected surfaces. If other otherwise specifies that deicing boots deicing cycle after leaving icing solutions are identified, the FAA may should not be used for certain phases of conditions.’’ consider further rulemaking. flight (e.g., take-off, final approach, and Regarding the commenter’s second landing), compliance with the following request, the FAA considers that, since 9. Request To Revise AFM Change is required.’’ the suggested change would alter the One commenter requests that the With respect to the request to specify actions currently required by this AD, proposal to operate the boots at the first that the deicing boots must not be used additional rulemaking would be sign of ice accretion be limited to the during take-off and landing, it would be required. The FAA finds that to delay holding and approach phases of flight. desirable to customize the AFM this action would be inappropriate in The commenter states that the Aviation limitation for specific models of light of the identified unsafe condition.

VerDate 29-OCT-99 11:34 Nov 19, 1999 Jkt 190000 PO 00000 Frm 00005 Fmt 4700 Sfmt 4700 E:\FR\FM\A22NO0.147 pfrm02 PsN: 22NOR1 63566 Federal Register / Vol. 64, No. 224 / Monday, November 22, 1999 / Rules and Regulations

However, the FAA is considering may conflict with current AFM ice detector system, whichever occurs additional rulemaking concerning procedures and could confuse operators. first. The FAA considers that, regardless operating speeds during icing The FAA does not concur that of what geographic area an airplane may conditions. substituting mandatory training for be flying in or what season of the year issuance of an AD is appropriate in this it may be, the boot system must be 11. Requests the FAA Consider the Pilot case. The FAA acknowledges that, in activated if those specified conditions Workload addition to the issuance of an AD, occur. One commenter states that the information specified in the revision to Regarding dispatch with an proposal would require the pilot to the AFM should be integrated into the inoperative boot, current Master monitor ice formation and to activate pilot training syllabus. However, the Minimum Equipment List (MMEL) the deicing system almost constantly. development and use of advisory procedures prohibit dispatch of the Another commenter suggests that such materials and training alone are not airplane into known or forecast icing increase of the pilot’s workload could, adequate to address the unsafe conditions if the deicing boots are of itself, cause an indirect adverse condition. The only method of ensuring inoperative. In the event that icing impact on operational safety. The that certain information is available to, conditions are inadvertently commenters request that the FAA and mandatory for, the pilot is through encountered during operation in consider the additional pilot workload if incorporation of the information into accordance with MMEL provisions, the proposal is adopted. the Limitations Section of the AFM. The procedures exist to instruct the The FAA has previously considered appropriate vehicle for requiring such flightcrew to exit the icing conditions the effects on the pilot of requiring that revision of the AFM is issuance of an immediately. The FAA considers that the deicing boots be activated at the first AD. No change is necessary to the final those existing procedures will prevent sign of ice formation anywhere on the rule in this regard. conflict between the requirements of airplane, or upon annunciation from an this AD and perceived problems 13. Request To Consider Procedures ice detector system. The FAA regarding dispatch with inoperative acknowledges that current procedures Already in Normal Procedures Section boots. No change is necessary to the recommending activation of the deicing One commenter requests concurrence final rule in this regard. boots at a specific ice accretion that procedures existing in the Normal thickness require the flightcrew to Procedures section of the AFM be 15. Request To Consider Differences in closely monitor the ice accretion. considered as compliant with the Airplanes Systems However, since a number of airplanes requirements of the proposed AD. One commenter requests that the affected by this AD are equipped with The FAA does not concur that AFM revision specified in paragraph (a) deicing boot systems with automatic procedures specified in the Normal of the proposed rule be revised for those operating modes, operating the deicing Procedures section of the AFM are an airplanes that are equipped with icing boots at the first sign of ice accretion in equivalent method of compliance with detection systems. Such a revision an appropriate automatic mode will the AD. The FAA considers that, since should read ‘‘activate the wing and tail favorably influence flightcrew the Limitations section of the AFM is leading edge pneumatic deicing boot workload. For airplanes not equipped the only section of the AFM that is system upon annunciation from an ice with automatic deicing boot operating mandatory [§ 91.9 of the Federal detector,’’ rather than ‘‘at the first sign modes, periodic operation of the boots Aviation Regulations (14 CFR 91.9)], the of ice anywhere on the aircraft, or upon can be accomplished based on time subject required revision to the AFM annunciation from an ice detector intervals consistent with existing icing must be included in the Limitations system, whichever occurs first.’’ The conditions. The FAA considers that section. No change is necessary to the commenter states that, since the sensor periodic operation of the boots is not a final rule in this regard. for the ice detection system detects ice greater workload burden than closely buildup at the boot, it would make 14. Request To Limit the AD to Only monitoring the ice accretion thickness. sense for airplanes that have an ice For the reasons stated, the FAA has Those Operations Conducive to Icing detection system to activate the boot determined that it is unnecessary to Two commenters request that the only when ice is detected at the boot by revise the final rule. AFM limitation specified in paragraph the ice detection system. The (a) of the proposal be limited to those commenter further points out that 12. Request To Withdraw the Proposal: conditions where operations conducive activating the boot when ice is not Provide Training Instead to icing exist. The commenters provide forming on the boot will not remove the Several commenters request that the examples of conditions where ice formations elsewhere on the FAA withdraw the proposal and ensure operations not conducive to icing may airplane, but will simply deteriorate the that appropriate information and exist such as Hawaii; the Caribbean; condition of the boot and provide no training regarding the use of the boots short, low altitude flights in the safety benefit. Additionally, the is provided to pilots. The commenters summer; etc. One of these commenters commenter adds that if the ice detection also suggest that a testing program be states that, ‘‘under the proposal, system were inoperative for dispatch, it accomplished by industry. The dispatch with an inoperative boot would be appropriate as a Master commenters assert that such training, would be considered prohibited even Minimum Equipment List (MMEL) along with an analysis of the testing though the deicing would never be condition to activate the boot at the first program, would eliminate the need for needed.’’ sign of icing. requiring that the deicing boots be The FAA does not concur that The FAA does not concur that the activated in accordance with the revision of the AD is necessary in this final rule should be revised to address proposal. One commenter also adds that regard. Paragraph (a) of the AD procedures specifically for airplanes the AFM should only be changed to add specifically states that wing and tail equipped with icing detection systems. a warning that delayed activation of the leading edge pneumatic deicing boot Visual detection of icing by the pneumatic boot system may be unsafe. systems must be activated at the first flightcrew has been certificated as the Another commenter adds that the sign of ice formation anywhere on the primary means of ice detection. language of the proposed AFM revision aircraft, or upon annunciation from an Therefore, the FAA has determined that,

VerDate 29-OCT-99 11:34 Nov 19, 1999 Jkt 190000 PO 00000 Frm 00006 Fmt 4700 Sfmt 4700 E:\FR\FM\A22NO0.148 pfrm02 PsN: 22NOR1 Federal Register / Vol. 64, No. 224 / Monday, November 22, 1999 / Rules and Regulations 63567 although ice detection systems may alert ability of the flightcrew to either appropriate application interval at this the flightcrew to the presence of icing, identify that the airfoil has ice adhering time. However, if additional data the flightcrew is still responsible to to it or accurately determine that a becomes available, the FAA may monitor the airframe for ice accretion. certain thickness of ice exists on the consider further rulemaking. No change is necessary to the final rule airfoil prior to activation of the boot 19. Request To Consider the Associated in this regard. However, in the event a system. Maintenance Procedures and Increased turbopropeller airplane equipped with The FAA concurs that installation of Costs pneumatic deicing boots was also a reliable ice detection system would equipped with an ice detection system alleviate the difficulties associated with Several commenters point out that that was approved as the primary ice flightcrew recognition of airfoil ice certain maintenance requirements detection system, the operator could accretions. This issue is being addressed should be considered if the proposed request an alternative method of by an ARAC working group. Upon AFM revision is required. One compliance in accordance with receipt of a recommendation from commenter notes that a detailed review paragraph (b) of the final rule. ARAC, the FAA may consider further of maintenance procedures should be rulemaking. In the interim, the FAA is conducted regarding the deicing boots 16. Request To Require Additional issuing these airworthiness directives to to ensure that, as the boot ages, the boot Operational Procedures impose a relatively simple deicing boot system continues to effectively shed ice. Several commenters propose that the operational change to address the Several commenters request that the FAA consider that minimum speed reduced handling qualities or FAA also consider the additional costs restrictions be used in conjunction with controllability of the airplane due to ice that the proposed AFM revision would the early activation of the deicing boots. accumulations on the protected require. One commenter states that the Some of the commenters specify that surfaces. No change is necessary to the added cycling of the boots will require these speed additions be applied during final rule in this regard. additional maintenance. The landing approach. One of the commenters express concern that the commenters expresses concern that 18. Request To Require Action To boots will wear out faster, need to be various reports and research indicate Reduce Adhesion Characteristics replaced at an accelerated rate, and that increasing the angle-of attack with One commenter requests that action thereby add additional costs. even a small ice formation on the airfoil be taken to minimize or reduce the ice The FAA acknowledges the concerns can cause large increases in drag and adhesion characteristics of boot of these commenters. The FAA loss of lift. The commenter contends material. The commenter asserts that considered the deicing boot fatigue that control of the angle-of-attack is one reason flightcrews may be seeing issues surrounding the proposed AD, critical in maintaining airfoil large amounts of residual ice may be such as the reliability of the deicing performance, and concludes that that, as the boot ages, the tendency for boots. Reliability of the deicing boots is additional operational procedures must residual ice to stick to the boot surface affected by several factors, including: be added. may increase if the adhesion qualities of maintenance practices; abrasion during The FAA concurs that certain the boot materials are not properly dry air, rain, hail, snow, and icing operational procedures may be maintained. In addition, the commenter operations; oxidation; and, fatigue beneficial when used with early suggests that the use of certain resulting from boot cycling. activation of the deicing boots. As a compounds (e.g., ICEX, an ice-phobic However, none of the commenters complement to this AD, the FAA is chemical spray) can reduce ice adhesion provided cost estimates for any of the considering rulemaking regarding by substantial margins. maintenance costs or replacement costs. minimum speeds in icing conditions. As The FAA does not concur with the The FAA did receive certain other mentioned previously, the FAA commenter’s request to require information from a large operator of two encourages manufacturers to present rulemaking to reduce adhesion airplane models that will be affected by data via a request for approval of an characteristics of boot material. The this final rule. (One of the airplane alternative method of compliance to FAA considers that normal wear and models in that fleet currently observes substantiate that their airplanes are tear on the deicing boot materials is to the early-activation procedures required either capable of flying safely with ice be expected, and the adhesion by this final rule and the other airplane that accumulates prior to boot characteristics of the boot increases as model does not.) The operator stated activation, or that they are not capable the boot surface degrades over time. that the largest contributor to periodic of flying safely but there are other Operators have the responsibility to replacement of deicing boots on the fleet means to address the unsafe condition. monitor the performance of the deicing was erosion of the boot surface, rather For example, in the case of Cessna boots installed on their airplanes, and to than fatigue that would be caused by Model 560 series airplanes, the stall perform maintenance as required. activation of deicing boots at the first warning margins were modified to The FAA acknowledges that use of sign of ice accretion. ensure the airplane could safely operate certain ice-phobic chemicals may The FAA recognizes that, in with ice accretions on the protected provide an additional safety benefit. accomplishing the requirements of any surfaces. No change is necessary to the However, a variety of factors (e.g., AD, operators may incur ‘‘incidental’’ final rule in this regard. normal wear and tear, ‘‘patching,’’ and costs in addition to the ‘‘direct’’ costs oxidation of boot material) exist in that are reflected in the cost analysis 17. Request To Mandate Installation of varying degrees on individual airplanes. presented in the AD preamble. an Ice Detection System As a result, the optimum frequency of However, the cost analysis in AD One commenter suggests that a application will vary during the life of rulemaking actions typically does not required installation of a reliable ice the boot. The FAA has received no include incidental costs. In the case of detection system might alleviate the quantitative data to demonstrate the this AD, for example, the requirements difficulties associated with flightcrew adequacy of particular amounts of ice are to revise the AFM to include certain recognition of airfoil ice accretions. The phobic chemical sprays or to provide information. How operators actually commenter notes that, historically, the adequate intervals of application. ‘‘implement’’ that information thereafter problem of ice detection has been the Therefore, the FAA cannot establish an (once it is placed in the AFM) may vary

VerDate 29-OCT-99 18:57 Nov 19, 1999 Jkt 190000 PO 00000 Frm 00007 Fmt 4700 Sfmt 4700 E:\FR\FM\22NOR1.XXX pfrm02 PsN: 22NOR1 63568 Federal Register / Vol. 64, No. 224 / Monday, November 22, 1999 / Rules and Regulations greatly among them: for some operators, will not have a significant economic deactivated only after completion of an entire implementation may necessitate impact, positive or negative, on a deicing cycle after leaving icing conditions.’’ extensive retraining among their substantial number of small entities (b) An alternative method of compliance or under the criteria of the Regulatory adjustment of the compliance time that flightcrews; for others, implementation provides an acceptable level of safety may be may merely be considered a typical part Flexibility Act. A final evaluation has used if approved by the Manager, Wichita of the routine, continuous training of been prepared for this action and it is Aircraft Certification Office, FAA, Small their flightcrews. In light of this, it contained in the Rules Docket. A copy Airplane Directorate. The request shall be would be nearly impossible for the FAA of it may be obtained from the Rules forwarded through an appropriate FAA to calculate accurately or to reflect all Docket at the location provided under Operations Inspector, who may add costs associated with the AFM revision the caption ADDRESSES. comments and then send it to the Manager, Wichita ACO. required by this AD. The FAA has List of Subjects in 14 CFR Part 39 determined that direct and incidental Note 1: Information concerning the costs are still outweighed by the safety Air transportation, Aircraft, Aviation existence of approved alternative methods of safety, Safety. compliance with this AD, if any, may be benefits of the AD. obtained from the Wichita ACO. Conclusion Adoption of the Amendment (c) Special flight permits may be issued in After careful review of the available Accordingly, pursuant to the accordance with §§ 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 data, including the comments noted authority delegated to me by the Administrator, the Federal Aviation and 21.199) to operate the airplane to a above, the FAA has determined that air location where the requirements of this AD safety and the public interest require the Administration amends part 39 of the can be accomplished. adoption of the rule with the changes Federal Aviation Regulations (14 CFR (d) This amendment becomes effective on described previously. The FAA has part 39) as follows: December 27, 1999. determined that these changes will Issued in Renton, Washington, on PART 39ÐAIRWORTHINESS neither increase the economic burden November 10, 1999. DIRECTIVES on any operator nor increase the scope John J. Hickey, of the AD. 1. The authority citation for part 39 Manager, Transport Airplane Directorate, Aircraft Certification Service. Cost Impact continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. [FR Doc. 99–30131 Filed 11–19–99; 8:45 am] There are approximately 283 Model BILLING CODE 4910±13±U NA–265–40, NA–265–60, NA–70, and, § 39.13 [Amended] NA–265–80 series airplanes of the 2. Section 39.13 is amended by affected design in the worldwide fleet. adding the following new airworthiness DEPARTMENT OF TRANSPORTATION The FAA estimates that 176 airplanes of directive: U.S. registry will be affected by this AD. Federal Aviation Administration It will take approximately 1 work 99–19–03 Sabreliner Corporation: Amendment 39–11292. Docket 99–NM– 14 CFR Part 39 hour per airplane to accomplish the 137–AD. required AFM revisions, at the average Applicability: Model NA–265–40, NA– [Docket No. 99±NM±140±AD; Amendment labor rate of $60 per work hour. Based 265–60, NA–70, and NA–265–80 series 39±11295; AD 99±19±06] on these figures, the cost impact of the airplanes equipped with pneumatic deicing RIN 2120±AA64 AD on U.S. operators is estimated to be boots, certificated in any category. $10,560, or $60 per airplane. Compliance: Required as indicated, unless Airworthiness Directives; Mitsubishi The cost impact figure discussed accomplished previously. To ensure that flightcrews activate the Model YS±11 and YS±11A Series above is based on assumptions that no Airplanes operator has yet accomplished any of wing and tail pneumatic deicing boots at the first signs of ice accumulation on the the requirements of this AD action, and AGENCY: Federal Aviation airplane, accomplish the following: that no operator would accomplish (a) Within 10 days after the effective date Administration, DOT. those actions in the future if this AD of this AD: Revise the Limitations Section of ACTION: Final rule. were not adopted. the FAA-approved Airplane Flight Manual (AFM) to include the following requirements SUMMARY: This amendment adopts a Regulatory Impact for activation of the ice protection systems. new airworthiness directive (AD), The regulations adopted herein will This may be accomplished by inserting a applicable to certain Mitsubishi Model not have substantial direct effects on the copy of this AD in the AFM. YS–11 and YS–11A series airplanes, • States, on the relationship between the ‘‘ Except if the AFM otherwise specifies that requires revising the Airplane national government and the States, or that deicing boots should not be used for Flight Manual (AFM) to include certain phases of flight (e.g., take-off, final on the distribution of power and approach, and landing), compliance with the requirements for activation of the responsibilities among the various following is required. airframe pneumatic deicing boots. This levels of government. Therefore, in • Wing and Tail Leading Edge Pneumatic amendment is prompted by reports of accordance with Executive Order 12612, Deicing Boot System, if installed, must be inflight incidents and an accident that it is determined that this final rule does activated: occurred in icing conditions where the not have sufficient federalism —At the first sign of ice formation anywhere airframe pneumatic deicing boots were implications to warrant the preparation on the aircraft, or upon annunciation from not activated. The actions specified by of a Federalism Assessment. an ice detector system, whichever occurs this AD are intended to ensure that For the reasons discussed above, I first; and flightcrews activate the pneumatic wing —The system must either be continued to be certify that this action (1) is not a operated in the automatic cycling mode, if and tail deicing boots at the first signs ‘‘significant regulatory action’’ under available; or the system must be manually of ice accumulation. This action will Executive Order 12866; (2) is not a cycled as needed to minimize the ice prevent reduced controllability of the ‘‘significant rule’’ under DOT accretions on the airframe. aircraft due to adverse aerodynamic Regulatory Policies and Procedures (44 • ‘‘The wing and tail leading edge effects of ice adhering to the airplane FR 11034, February 26, 1979); and (3) pneumatic deicing boot system may be prior to the first deicing cycle.

VerDate 29-OCT-99 11:34 Nov 19, 1999 Jkt 190000 PO 00000 Frm 00008 Fmt 4700 Sfmt 4700 E:\FR\FM\A22NO0.150 pfrm02 PsN: 22NOR1