Tuesday, November 26, 2002

Part II

Department of Transportation Federal Aviation Administration

14 CFR Parts 1, 25, and 97 1-g Stall Speed as the Basis for Compliance With Part 25 of the Federal Aviation Regulations; Final Rule

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DEPARTMENT OF TRANSPORTATION Docket you selected, click on the For example, under part 25, V2 must be document number for the item you wish at least 1.2 times VS, the final takeoff Federal Aviation Administration to view. climb speed must be at least 1.25 times You can also get an electronic copy VS, and the landing approach speed 14 CFR Parts 1, 25, and 97 using the Internet through the Office of must be at least 1.3 times VS. [Docket No. 28404; Amendment Nos. 1–49, Rulemaking’s Web page at http:// The speed margin, or difference in 25–108, 97–1333] www.faa.gov/avr/armhome.htm or the speed, between VS and each minimum Federal Register’s Web page at http:// operating speed provides a safety RIN 2120–AD40 www.access.gpo.gov/su_docs/aces/ ‘‘cushion’’ to ensure that normal aces140.html. operating speeds are sufficiently higher 1-g Stall Speed as the Basis for You can also get a copy by submitting than the speed at which the airplane Compliance With Part 25 of the Federal a request to the Federal Aviation stalls. Using multiplying factors applied Aviation Regulations Administration, Office of Rulemaking, to VS to provide this speed margin, AGENCY: Federal Aviation ARM–1, 800 Independence Avenue however, assumes that VS provides a Administration (FAA), DOT. SW., Washington, DC, 20591, or by proper reference stall speed. Since VS is calling (202) 257–9680. Make sure to ACTION: Final rule. the minimum speed obtained in the identify the amendment number or stalling maneuver, it can be less than SUMMARY: This action amends the docket number of this rulemaking. the lowest speed at which the airplane’s airworthiness standards for transport Small Business Regulatory Enforcement weight is still supported entirely by category airplanes to redefine the Fairness Act aerodynamic lift. If VS is significantly reference stall speed for transport less than this speed, applying The Small Business Regulatory category airplanes as a speed not less multiplying factors to VS to determine than the 1-g stall speed instead of the Enforcement Fairness Act (SBREFA) of the minimum operating speeds may not minimum speed obtained in a stalling 1996 requires FAA to comply with provide as large a speed margin as maneuver. The FAA is taking this action small entity requests for information or intended. to provide for a consistent, repeatable advice about compliance with statutes A proper reference stall speed should reference stall speed; ensure consistent and regulations within its jurisdiction. provide a reasonably consistent and dependable maneuvering margins; Therefore, any small entity that has a approximation of the wing’s maximum provide for adjusted multiplying factors question regarding this document may usable lift. Maximum usable lift occurs to maintain approximately the current contact their local FAA official, or the at the minimum speed for which the lift requirements in areas where use of the person listed under FOR FURTHER provided by the wing is capable of minimum speed in the stalling INFORMATION CONTACT. You can find out supporting the weight of the airplane. maneuver has proven adequate; and more about SBREFA on the Internet at This speed is known as the 1-g stall harmonize the applicable regulations our site, http://www.faa.gov/avr/arm/ speed because the load factor (the ratio with those currently adopted in Change sbrefa.htm. For more information on of airplane lift to weight) at this speed 15 to the European Joint Aviation SBREFA, e-mail us at 9–AWA– is equal to 1.0 ‘‘g’’ (where ‘‘g’’ is the Requirements-25 (JAR–25). These [email protected]. acceleration caused by the force of gravity) in the direction perpendicular changes will provide a higher level of Background safety for those cases in which the to the flight path of the airplane. Speeds These amendments are based on lower than the 1-g stall speed during the current methods result in artificially notice of proposed rulemaking (NPRM) low operating speeds. stalling maneuver represent a transient Notice No. 95–17, which was published flight condition that, if used as a EFFECTIVE DATE: December 26, 2002. in the Federal Register on January 18, reference for the deriving minimum FOR FURTHER INFORMATION CONTACT: Don 1996 (61 FR 1260). In that notice, the operating speeds, may not provide the Stimson, Airplane and Flightcrew FAA proposed amendments to 14 CFR desired speed margin to protect against Interface Branch, ANM–111, Transport parts 1, 25, 36, and 97 to redefine the inadvertently stalling the airplane. Airplane Directorate, Aircraft reference stall speed (VSR) for transport For transport category airplanes, the Certification Service, FAA, 1601 Lind category airplanes as the 1-g stall speed minimum speed obtained in the stall Avenue SW., Renton, WA 98055–4056; instead of the minimum speed obtained maneuver of § 25.103 usually occurs telephone (425) 227–1129; facsimile in the stalling maneuver. The FAA near the point in the maneuver where (425) 227–1320, e-mail received nearly 40 comments from 12 the airplane spontaneously pitches [email protected]. different commenters on the proposals nose-down or where the pilot initiates SUPPLEMENTARY INFORMATION: contained in Notice No. 95–17. As a recovery after reaching a deterrent level result of these comments, this final rule of buffet, i.e., a vibration of a magnitude Availability of Rulemaking Documents differs in some aspects from the original and severity that is a strong and You can get an electronic copy using proposals. effective deterrent to further speed the Internet by taking the following As explained in Notice No. 95–17, the reduction. Early generation transport steps: stalling speed (VS) is defined as the category airplanes, which had fairly (1) Go to the search function of the minimum speed demonstrated in the straight wings and non-advanced Department of Transportation’s performance stall maneuver described airfoils, typically pitched nose-down electronic Docket Management System in § 25.103 of 14 CFR part 25 (part 25). near the 1-g stall speed. The minimum (DMS) web page (http://dms.dot.gov/ VS has historically served as a reference speed in the maneuver was easy to note search). speed for determining the minimum and record, and served as an adequate (2) On the search page type in the last operating speeds required under part 25 approximation of the speed for four digits of the Docket number shown for transport category airplanes. maximum lift. at the beginning of this notice. Click on Examples of minimum operating speeds For the recent generation of high ‘‘search.’’ that are based on VS include the takeoff speed transport category airplanes with (3) On the next page, which contains safety speed (V2), the final takeoff climb swept wings and highly advanced the Docket summary information for the speed, and the landing approach speed. airfoils, however, the minimum speed

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obtained in the stalling maneuver can be maneuver, the FAA has been push the nose down (e.g., stick pushers) substantially lower than the speed for encouraging applicants to use the 1-g near the angle of attack for maximum maximum lift. Furthermore, the point at stall speed methodology in lieu of the lift. These devices are typically installed which the airplane pitches nose down minimum speed obtained in the stalling on airplanes with unacceptable natural or exhibits a deterrent level of buffet is maneuver. Applicants generally desire stalling characteristics. The abrupt nose more difficult to distinguish and can to use 1-g stall speeds because the 1-g down push provides an artificial stall vary with piloting technique. As a stall speeds are less dependent on pilot indication and acceptable stall result, the minimum speed in the technique and other subjective characteristics, and prevents the stalling maneuver has become an evaluations. Hence, 1-g stall speeds are airplane from reaching a potentially inappropriate reference for most modern easier to predict and provide a higher hazardous natural aerodynamic stall. high speed transport category airplanes level of confidence for developing Typically, the minimum speed obtained for establishing minimum operating predictions of overall airplane in this maneuver is approximately equal speeds since it may: (1) Be performance. Again, reduced to the 1-g stall speed. inconsistently determined, and (2) multiplying factors are applied to the 1- Traditionally, the existing multiplying represent a flight condition in which the g stall speeds to obtain minimum factors have been applied to these load factor perpendicular to the flight operating speeds equivalent to the airplanes. The proposal to define the path is substantially less than 1.0 g. speeds that have been found acceptable reference stall speed as the 1-g stall In recent years, advanced technology in operational service. Using 1-g stall speed would generally have no impact transport category airplanes have been speeds ensures that the airplane’s for these airplanes, but reducing the developed that employ novel flight minimum operating speeds will not be multiplying factors would allow lower control systems. These flight control unreasonably low. minimum operating speeds to be systems incorporate unique protection established. Therefore, this proposal features that are intended to prevent the Discussion of the Proposals would allow these airplanes to be airplane from stalling. They also prevent In Notice No. 95–17, the FAA operated at speeds and angles of attack the airplane from maintaining speeds proposed to define the reference stall closer to the pusher activation point that are slower than a small percentage speed in § 25.103 as a speed not less than has been experienced in above the 1-g stall speed. Because of than the 1-g stall speed, rather than the operational service. their unique design features, the minimum speed obtained in the stalling The FAA considered this reduction in traditional method of establishing VS as maneuver. This proposal was made to operating speeds for pusher-equipped the minimum speed obtained in the provide a consistent basis for use in all airplanes to be acceptable, provided the stalling maneuver was inappropriate for type design certification requirements pusher reliably performs its intended these airplanes. The FAA issued special for transport category airplanes. The function and that unwanted operation is conditions for these airplanes to define FAA proposed to introduce the symbol minimized. The FAA has addressed the the reference stall speed as not less than VSR to represent this speed and to majority of these concerns in a revision the 1-g stall speed for the flight indicate that it is different than the to Advisory Circular (AC) 25–7, the requirements contained in subpart B of minimum speed obtained in the stalling ‘‘Flight Test Guide for Certification of part 25. maneuver, VS. Transport Category Airplanes.’’ This In these special conditions, the In addition, the FAA proposed to revision, AC 25–7A, dated March 31, multiplying factors used to determine reduce the multiplying factors that are 1998, provides criteria for the design the minimum operating speeds were used in combination with the reference and function of stall indication systems, reduced in order to maintain stall speed to determine the minimum including arming and disarming, equivalency with acceptable operating operating speeds by approximately 6 indicating and warning devices, system speeds used by previous transport percent. This change would result in reliability and safety, and system category airplanes. Since the 1-g stall minimum operating speeds equivalent functional requirements. The FAA plans speed is generally higher than the to those for most current transport to address other concerns, such as minimum speed obtained in the stalling category airplanes since the 1-g stall system design and manufacturing maneuver, retaining the current speed for these airplanes is tolerances, and system design features multiplying factors would have resulted approximately 6 percent higher than the like filtering and phase advancing, in a in higher minimum operating speeds for minimum speed obtained in the stalling future revision to AC 25–7A. airplanes using the 1-g stall speed as a maneuver. Demonstrating a minimum In addition to proposing to define the basis for the reference stall speed. stalling speed more than 6 percent reference stall speed as a speed not less However, increasing the minimum slower than the 1-g stall speed, which than the 1-g stall speed and to reduce operating speeds could impose costs on is possible under the current standards, the multiplying factors for establishing operators because payloads might have would provide an unacceptable basis for the minimum operating speeds, the to be reduced to comply with the determining the minimum operating FAA also proposed to require applicants regulations at the higher operating speeds. The proposed standards would to demonstrate adequate maneuvering speeds under some performance-limited prevent this situation from occurring. In capability during the takeoff climb, en conditions. Based on the service this respect, the proposed standards route climb, and landing approach experience of the current fleet of would provide a higher level of safety phases of flight. During a banked turn, transport category airplanes, the costs than the existing standards. a portion of the lift generated by the imposed would not be offset by a However, the proposed reduced wing provides a force to help turn the commensurate increase in safety. factors would allow lower minimum airplane. To remain at the same altitude, Several airplane types with operating speeds to be established for the airplane must produce additional conventional flight control systems have those airplanes that have a minimum lift. Therefore, banking the airplane (at also been certificated using the 1-g stall speed in the stalling maneuver a constant speed and altitude) reduces speed as a lower limit to the reference approximately equal to the 1-g stall the stall margin, which is the difference stall speed. Because of the potential speed. One particular class of airplanes between the lift required for the deficiencies in using the minimum for which this applies is airplanes maneuver and the maximum lift speed demonstrated in the stalling equipped with devices that abruptly capability of the wing. As the bank

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angle increases, the stall margin is change the wording of this requirement 1-g stall speed is not likely to be a reduced proportionately. This bank to replace ‘‘VS’’ with ‘‘the stall,’’ catastrophic occurrence, the FAA angle effect on the stall margin can be ‘‘§ 25.103(b)(1)’’ with ‘‘§ 25.103(a)(6),’’ considers such a small stall warning determined analytically, and the and ‘‘at any speed’’ with ‘‘at any point.’’ margin to be unacceptable. The FAA multiplying factors applied to VSR to These changes would be consistent with proposed requiring a stall warning determine the minimum operating the proposed change to the definition of margin of at least 3 knots or 3 percent, speeds are intended to ensure that an the reference stall speed and the whichever is greater, relative to VSR. adequate stall margin is maintained. proposed reformatting of § 25.103. The FAA’s proposal was made on the In addition to the basic effect of bank Although compliance with § 25.145(a) basis that this margin represents a angle, however, modern wing designs must be demonstrated both with power reasonable balance between providing also typically exhibit a significant off and with maximum continuous the pilot with enough warning to avert reduction in maximum lift capability power, there is no intention to require an impending stall, and providing with increasing Mach number. The flight test demonstrations of full stalls at adequate maneuvering capability at the magnitude of this Mach number effect engine powers above that specified in minimum operating speeds. This depends on the design characteristics of § 25.201(a)(2). Instead of performing a proposal would retain the existing level the particular wing. For wing designs full stall at maximum continuous of safety. with a large Mach number effect, the power, compliance will be assessed by The FAA proposed to require a larger maximum bank angle that can be demonstrating sufficient static stall warning margin for airplanes achieved while retaining an acceptable longitudinal stability and nose down equipped with devices that abruptly stall margin can be significantly control margin when the deceleration is push the nose down at a selected angle reduced. Because the effect of Mach ended at least one second past stall of attack (e.g., stick pushers). number can be significant, and because warning during a one knot per second Inadvertent operation of such a device, it can also vary greatly for different wing deceleration. The static longitudinal especially close to the ground, can have designs, the multiplying factors applied stability during the maneuver and the more serious consequences than a toVSR are insufficient to ensure that nose down control power remaining at comparable situation in which the pilot adequate maneuvering capability exists the end of the maneuver must be of an airplane without the device at the minimum operating speeds. sufficient to assure compliance with the inadvertently slows to VSR. Therefore, To address this issue, the FAA requirement. the FAA proposed adding § 25.207(d) to proposed to require a minimum bank Section 25.207 requires that a warning require the stall warning, for airplanes angle capability in a coordinated turn of an impending stall must be provided equipped with one of these devices, to without encountering stall warning or in order to prevent the pilot from occur at least 5 knots or 5 percent, any other characteristic that might inadvertently stalling the airplane. The whichever is greater, above the speed at interfere with normal maneuvering. warning must occur at a speed which the device activates. This This requirement would be added to sufficiently higher than the stall speed proposal was made on the basis of § 25.143 as a new paragraph (g). The to allow the pilot time to take action to retaining the existing level of safety for proposed minimum bank angles were avoid a stall. The speed difference airplanes equipped with such devices. derived by adding a 15 degree between the stall speed and the speed The FAA proposed to add a new allowance for wind gusts and at which the stall warning occurs is paragraph, § 25.207(e), to require that, in inadvertent overshoot to a maneuvering known as the stall warning margin. The a slow-down turn with load factors up capability the FAA considers necessary FAA proposed amending the size of the to 1.5 g and deceleration rates up to 3 for the specific cases identified in the stall warning margin required by knots per second, sufficient stall proposed new paragraph. These § 25.207(c) because of the change in warning must exist to prevent stalling proposed maneuver margin definition of the reference stall speed. when recovery is initiated not less than requirements would increase the level Currently, the stall warning must one second after stall warning occurs. of safety in maneuvering flight. begin at a speed exceeding VS by seven The FAA considered this proposed Consistent with the proposed knots, or a lesser margin if the stall requirement necessary to provide maneuver margin requirements, the warning has enough clarity, duration, adequate stall warning during a FAA proposed adding §§ 25.107(c)(3), distinctiveness, or other similar dynamic maneuver, such as a collision 25.107(g)(2), and 25.125(a)(2)(iii) to properties. Requiring the same seven avoidance maneuver. In addition, this reference § 25.143(g) in the list of knot warning margin to be provided new paragraph would provide a constraints applicants must consider relative to VSR would result in an quantitative requirement with which to when selecting the minimum takeoff increase to the minimum operating assess whether ‘‘sufficient margin to safety speed, final takeoff speed, and speeds. This increase in the minimum prevent inadvertent stalling * * * in reference landing speeds, respectively. operating speeds would be necessary to turning flight’’ has been provided as The normal all-engines-operating takeoff meet the maneuvering margin required by § 25.207(a). This proposal climb speed selected by the applicant requirements proposed in § 25.143(g), would increase the level of safety during would also have to provide the which are defined relative to the stall maneuvering flight. minimum bank angle capability warning speed. However, as discussed The FAA proposed to add a new specified in the proposed § 25.143(g). previously, requiring an increase to the paragraph, § 25.207(f), to require that Section 25.145(a) requires that there minimum operating speeds would stall warning be provided for abnormal be adequate longitudinal control impose costs to airplane operators that airplane configurations likely to be used available to promptly pitch the cannot be justified by service following system failures. This proposal airplane’s nose down from at or near the experience. would add a requirement currently stall in order to return to the original On the other hand, if the stall warning contained in JAR–25 and is consistent trim speed. The intent of this margin were reduced to retain with current transport category airplane requirement is to ensure sufficient pitch approximately the same stall warning designs. There would be no impact on control for a prompt recovery if the speed, the warning would occur only the existing level of safety. airplane is inadvertently slowed to the one or two knots prior to reaching the On modern transport category point of stall. The FAA proposed to 1-g stall speed. Although reaching the airplanes, the natural buffet or vibration

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caused by the airflow separating and to incorporate reduced multiplying airplane. Also, VREF would refer to the reattaching itself to the wing as the factors throughout part 25, where speed at the landing screen height, airplane approaches the stall speed is appropriate, in requirements that use regardless of whether that speed for a usually not strong enough by itself to speeds based on a multiple of the particular airplane is 1.3 VS, 1.23 VSR, provide an effective stall warning. reference stall speed. The FAA also or some higher speed. Therefore, stall warning on modern proposed numerous minor wording and In the same manner, the FAA transport category airplanes is usually structural changes to various sections to proposed to amend § 97.3(b) by provided through an artificial means, improve editorial clarity and to replacing ‘‘1.3 VS0’’ with ‘‘VREF.’’ As such as a stick shaker that shakes the harmonize with the wording and noted above, VREF would refer to the pilot’s control column. Production structure proposed for JAR–25. Note speed at the landing screen height used tolerances associated with these systems that the proposed change to the term in establishing the approved landing can result in variations in the size of the ‘‘1.3 VS0’’ in § 25.175(d) reflects not only distance under the airworthiness stall warning margin for different the change in multiplying factor, but regulations constituting the type airplanes manufactured under the same also corrects a typographical error. (‘‘1.3 certification basis of the airplane, approved type design. VS0’’ should have been ‘‘1.8 VS0.’’) regardless of whether that speed for a The FAA considers the stall warning The FAA proposed to add the particular airplane is 1.3 VS, 1.23 VSR, margins proposed in §§ 25.207(c) and nomenclature ‘‘final takeoff speed’’ and or some higher speed. (d) to be the minimum acceptable ‘‘reference landing speed’’ and the These proposals were discussed warning margins, and that these margins abbreviations ‘‘VFTO’’ and ‘‘VREF’’ to extensively with the European Joint should not be reduced by production denote these speeds, respectively, to Aviation Authorities (JAA) with the tolerances associated with a system part 1 of the FAR. These terms and intent of harmonizing the certification added to the airplane to provide an abbreviations, which are commonly requirements related to stall speed for artificial stall warning. The FAA intends used in the aviation industry, would be transport category airplanes. The Joint for the proposed stall warning margins referenced throughout the proposed Aviation Requirements (JAR) 25 to be available at the most critical amendments to part 25. The reference prescribes the airworthiness standards tolerance expected in production. landing speed would be defined as the for transport category airplanes that are Applicants would be expected to speed of the airplane, in a specified accepted by the aviation regulatory demonstrate compliance with the landing configuration, at the point authorities of a number of European proposed stall warning margin either by where it descends through the landing states. The JAA introduced an flight testing with the stall warning screen height in the determination of equivalent proposal to the FAA’s NPRM system set to its critical tolerance the landing distance for manual 95–17, called Notice of Proposed setting, or by adjusting flight test data landings. The term ‘‘landing screen Amendment (NPA) 25B–215, to amend obtained at some other setting. height’’ refers to the height of the JAR–25 accordingly. The JAA’s final 1- The tolerances associated with the airplane at the beginning of the defined g stall requirements, which are stall warning system must also be landing distance. This height is equivalent to those adopted by the FAA considered in relation to the proposed normally 50 feet above the landing in this rulemaking, were adopted by the minimum maneuvering requirements of surface (see § 25.125(a)), but approvals JAA as part of Change 15 to JAR–25, § 25.143(g). As proposed, § 25.143(g) have been granted for steep approaches dated October 1, 2000. would require that the airplane be that use a landing screen height of 35 Discussion of the Comments capable of reaching a minimum bank feet. The final takeoff speed would be angle during a coordinated turn without defined as the speed of the airplane that The FAA received nearly 40 encountering stall warning. Because the exists at the end of the takeoff path in comments from 12 different commenters proposed requirements already provide the en route configuration with one on the proposals contained in Notice the capability to overshoot the intended engine inoperative. No. 95–17. The commenters include bank angle by 15 degrees, the small The FAA also proposed to add the airplane pilots, manufacturers, differences in the speed at which the abbreviations VSR, VSR0, and VSRI to part operators, and the associations stall warning system operates due to 1, and use them in part 25 to denote the representing them, foreign airworthiness system tolerances are not as critical. reference stall speed corresponding to authorities, an organization specializing Therefore, the FAA intends for the different airplane configurations. In in flight testing, and private citizens. In minimum bank angles in the proposed addition, the FAA proposed adding the general, the proposal to redefine the § 25.143(g) to apply at the designed abbreviation VSW to part 1 to refer to the reference stall speed for transport nominal setting of the stall warning speed at which the onset of stall category airplanes as the 1-g stall speed system. To ensure that large production warning occurs. instead of the minimum speed obtained tolerances do not adversely impact the The FAA proposed to amend in a stalling maneuver was supported, airplane’s maneuvering capability free § C36.9(e)(1) of Appendix C to part 36 although there were comments critical of stall warning, the bank angle by replacing ‘‘1.3 VS + 10 knots’’ with of specific details, and some capability specified in the proposed ‘‘VREF + 10 knots’’ and by removing the commenters were supportive only if the § 25.143(g) should not be reduced by words ‘‘or the speed used in current minimum speed method would more than two degrees with the stall establishing the approved landing be retained as an option that would be warning system operating at its most distance under the airworthiness available for the certification of small critical tolerance. Applicants would be regulations constituting the type transport category airplanes. expected to demonstrate this capability certification basis of the airplane, Those commenters who recommend either by flight test with the system set whichever speed is greatest.’’ The words retaining the minimum stall speed to its critical tolerance, or by proposed for deletion would no longer methodology for small transport analytically adjusting flight test data be necessary because VREF would category airplanes—small airplane obtained at some other setting. denote the speed used in establishing manufacturers and the association To be consistent with the proposed the approved landing distance under the representing them—believe that the revision of the definition of the airworthiness regulations constituting proposed changes introduce additional reference stall speed, the FAA proposed the type certification basis of the cost and complexity into applicants’

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type certification programs with no which this parameter is first a Organization’s (ICAO) Airworthiness increase in safety for this class of maximum. Experience to date with Technical Manual (Document 9051, airplanes. applicants voluntarily complying with 1987) uses the abbreviation VS1g to One manufacturer of small transport the proposed requirements has not denote the 1-g stall speed, which is the category airplanes notes that when 1-g highlighted any significant difficulties reference speed for determining the stall speeds were determined for one of in determining the 1-g stall speed using minimum operating speeds for transport their airplanes, the resulting operating typically existing data recording category airplanes with a certified speeds were virtually the same as those equipment. These applicants have takeoff mass of over 5,700 kg. The determined using the current included manufacturers of both large commenter suggests that the FAA could requirements. This commenter also and small transport category airplanes. further international standardization by states that variation in piloting The FAA is not surprised that for one adopting ICAO’s VS1g abbreviation to technique remains an issue even if the of the commenter’s airplane types, the denote the reference stall speed as a part stall speeds are defined as a 1-g current requirements and the 1-g stall of the rulemaking to redefine the condition, and a more expensive flight proposal yielded virtually the same reference stall speed as a 1-g stall speed. test data system is needed to determine minimum operating speeds. As noted in The FAA actively promotes where the 1-g stall break occurs. The Notice No. 95–17 and repeated in the international standardization and has commenter points out that straight (i.e., background discussion above, the been working closely with the non-swept) winged airplanes, for which proposed change to the multiplying regulatory authorities of Europe and the discussion in Notice No. 95–17 factors that are applied to the reference Canada during this rulemaking. The implied the current minimum speed stall speed to obtain the minimum FAA considered using the abbreviation method is adequate, will continue to be operating speeds was intentionally VS1g to denote the reference stall speed; designed and produced in the future. chosen to yield equivalent operating however, the reference stall speed may On airplanes with swept wings, due to speeds, on average, for current transport not always be equal to the 1-g stall different stiffness characteristics category airplanes. However, the speed. It is only required to be no less between large and small airplanes, proposed standards would prevent the than the 1-g stall speed. Other design which result in different responses to reference stall speed from being more constraints may dictate using a aerodynamic influences, the minimum than six percent slower than the 1-g stall reference stall speed that is higher than speed in the stalling maneuver is not speed, which the current standards do the 1-g stall speed. Since the reference difficult to obtain on small transport not prohibit. In this respect, the stall speed may be different than the 1- category airplanes. The commenter proposed standards would provide a g stall speed, the abbreviation VSR was concludes that the current methods higher level of safety than the existing proposed and has been adopted in § 1.2 should be retained for airplanes standards by ensuring that unreasonably to denote the reference stall speed. This weighing less than 75,000 pounds low minimum operating speeds will not abbreviation has also been adopted by because of the costs involved in be obtained. the JAA of Europe and is expected to be changing to the 1-g stall speed The FAA agrees that the use of a 1- adopted by the Canadian regulatory methodology for no apparent increase in g stall speed may not entirely remove authority. There were no comments on safety. (100,000 pounds is suggested as the effect of pilot technique from being the other proposed abbreviations nor on an appropriate cutoff by another a factor during the flight tests to the proposed definitions for final takeoff commenter.) determine the reference stall speed. speed and reference landing speed. The FAA disagrees that the proposed However, the use of a 1-g stall speed Therefore, these abbreviations and rule changes significantly increases cost would significantly mitigate this effect. definitions are adopted as proposed. and does not increase safety. Cost data Subjective assessments of airplane One commenter questions the reason supplied by one commenter behavior for identifying the stalled for the new wording in § 25.103(a)(1) to substantially overstates the incremental condition (using the criteria specified in describe the option of idle or zero cost of the test instrumentation and § 25.201(d)) would no longer be used to thrust. The commenter does not see the other items needed to support a 1-g stall determine the reference stall speed. new wording as an improvement in speed evaluation. This commenter (These criteria will continue to be used, clarity. The current rule states that zero allocates the entire cost of a new data however, for evaluating the airplane thrust must be used in determining the collection system, including purchase, handling characteristics during the stalling speed, except that idle thrust installation, and calibration, to the stalling maneuver.) Test pilot may be used when it does not proposed rule change, stating that this techniques that take advantage of these appreciably affect the stalling speed. new system would be needed to subjective assessments and allow Stated in this manner, the rule permits determine the ‘‘g-break’’ denoting the 1- unreasonably low load factors, and the use of zero thrust when idle thrust g stall speed. hence unreasonably low stall speeds, to causes an increase in the stalling speed. The only additional instrumentation be achieved would no longer be On some turboprop airplanes, where the FAA considers necessary to permitted. flight idle thrust may be negative, a determine the 1-g stall speed instead of In addition, it is usually much easier lower stall speed may be demonstrated the minimum speed in the stalling to measure airspeed accurately at the 1- using zero thrust than would occur with maneuver would be accelerometers g stall condition than at the minimum idle thrust. capable of resolving the load factor speed reached in the stalling maneuver. The FAA considers such a loss of stall normal to the flight path. At the Based on the experience gained from the speed margin in a normal flight minimum, one accelerometer aligned many type certification programs that condition to be unacceptable. In Notice along the expected 1-g stall pitch angle have already used the 1-g stall speed No. 95–17, the FAA proposed a change may provide acceptable data. methodology, the FAA has determined such that the reference stall speed must Determining the point at which the 1-g that this methodology provides a more be determined with idle thrust, except stall condition is reached is most readily consistent, repeatable reference stall in cases where that thrust level causes accomplished by a continuous speed than the existing method. an appreciable decrease in the stall calculation of the load factor-corrected One commenter notes that the speed. For such cases, not more than lift coefficient and noting the point at International Civil Aviation zero thrust must be used. There were no

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comments regarding the substance of Advisory Circular (AC) 25–7A, ‘‘Flight stall warning requirements represent an the proposed change; therefore, this Test Guide for Certification of Transport acknowledgment that the class of section is adopted as proposed. Category Airplanes,’’ to add clarifying airplanes cannot be treated the same as One commenter notes that while the guidance material. A notice of proposed conventionally stalling airplanes with proposal to the reference stall speed in advisory circular revisions was respect to minimum operating speeds terms of a 1-g stall speed would reduce published in the Federal Register on and associated margins. the amount of scatter in the flight test November 21, 2002. The FAA agrees with the commenter’s data used to determine the stall speed, Detailed comments were received analysis and fundamental principle that a significant amount of scatter would from one commenter regarding the effect in terms of the protection from stall remain. To further limit the amount of of the proposed rules on airplanes provided by such a device, the experimental error inherent in the data equipped with devices that abruptly characteristics resulting from its analysis process, the commenter push the nose down (e.g., stick pushers) operation, and its reliability and safety, suggests defining the reference stall to define the point of stall. As noted in there are significant differences from a speed in terms of the maximum normal Notice No. 95–17, this proposal would conventionally stalling airplane. Also, force coefficient instead of the allow airplanes equipped with such the difference between the 1-g stall maximum lift coefficient. Using the devices that have a trigger point set speed and the minimum speed obtained

normal force coefficient would yield close to or before CLMAX to achieve lower in the stalling maneuver for this class of slightly higher reference stall speeds, minimum operating speeds than under airplanes is closer to 0 to 3 percent, which could penalize an airplane’s load the existing requirements, and hence, rather than the 6 percent average for carrying capability due to the resulting operate at speeds and angles-of-attack conventionally stalling airplanes upon increase in minimum takeoff and closer to the device activation point which the reduction in operating speed landing speeds, but certification costs than has been experienced in factors was based. Permitting a might be reduced because the data operational service. The FAA reduction in the operating speeds for reduction process would be simplified. considered this aspect of the proposal to this class of airplanes could potentially The FAA agrees that defining the be acceptable provided the device result in a reduction in safety that is not reference stall speed in terms of the performs its intended function and justified by existing operational maximum normal force coefficient unwanted operation is minimized. experience. instead of the maximum lift coefficient The commenter points out that The commenter’s suggested additional may further reduce flight test data ensuring operation when desired and constraint on VSR represents a scatter and simplify data acquisition preventing unwanted operation are reasonable means to retain and analysis. However, these slight contradictory goals that result in design approximately equivalent safety without benefits are outweighed by the tradeoffs. Regardless of the design penalizing airplanes for which the potentially significant economic choice, however, allowing operation device trigger point is at an angle-of-

penalties associated with the resulting closer to the device activation point attack well beyond CLMAX. Therefore, higher reference stall speed. Many increases both the probability of § 25.103(d) is revised accordingly to recent airplane types have been certified reaching the activation point, where the require, for airplanes equipped with a using 1-g stall criteria similar to those device may fail to operate, and the device that abruptly pushes the nose contained in Notice No. 95–17 and this probability of unwanted operation. down at a selected angle-of-attack, that experience does not indicate any Considering these aspects, the VSR not be less than 2 percent or 2 significant problems in data quality or commenter contends that the proposed knots, whichever is greater, above the in the acquisition and analysis process. standards would reduce the level of speed at which the device operates. The Data scatter using the proposed 1-g stall safety relative to the current standards. suggested exception for turbopropeller criteria is inconsequential compared to The commenter suggests adding the powered airplanes that demonstrate a the data uncertainty inherent in the stipulation, for airplanes equipped with significant reduction in stall speed in current stall speed definition. Therefore, a device that abruptly pushes the nose the one-engine-inoperative power-on the commenter’s suggested change is not down at a selected angle-of-attack, that condition is not included, however, being adopted. However, the FAA VSR must not be less than the greater of because the applicable minimum would find it acceptable if an applicant 2 knots or 2 percent above the speed at operating speeds already allow for a proposed using the higher reference which the device activates. The significant effect of power on stall stall speeds derived from the maximum commenter further suggests that this speeds. normal coefficient in order to simplify additional requirement need not apply The effect of this provision is to the data acquisition and analysis to turbopropeller powered airplanes that increase the minimum operating speeds, process. The proposed amendment need demonstrate a significant reduction in relative to the Notice No. 95–17 not be changed to allow this option. stall speed in the one-engine- proposals, for airplanes equipped with A commenter suggests that it is inoperative power-on condition. The devices that abruptly push the nose technically more accurate in § 25.103(c) commenter points out that this down at a selected angle-of-attack, but to refer to the lift coefficient in the additional requirement is very similar in only if the device activates at a speed

definition of VCLMAX as the load factor- scope and intent to the Notice No. 95– higher than VCLMAX (at a load factor of corrected lift coefficient. The 17 proposed requirements for stall one) minus 2 knots or 2 percent. This commenter also considers the proposed warning, where, in addition to the requirement for a supplementary speed definition of VCLMAX to be ambiguous requirement applying to all transport margin, in combination with criteria and lacking in guidance material that category airplanes that stall warning be added to AC 25–7A, dated March 31, would provide clarification. Other 3 knots or 3 percent above VSR, the stall 1998, for system arming and disarming, commenters made various editorial and warning for airplanes equipped with indicating and warning devices, system formatting suggestions to further devices that abruptly push the nose reliability and safety, and system improve the clarity of § 25.103. The down at a selected angle-of-attack functional requirements are intended to FAA agrees with these suggestions and would be 5 knots or 5 percent above the provide an equivalent level of safety to has modified the proposal accordingly. speed at which the device operates. The the requirements existing prior to the In addition, the FAA proposes to revise commenter believes that the proposed adoption of this amendment. Other

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considerations, such as the effect of maneuvering capability to stall warning (e.g., turbulence, wind gusts) and an system design and manufacturing of less than the proposed 40 degrees of allowance for piloting imprecision (e.g., tolerances, and system design features bank, possibly as low as 27 degrees. inadvertent overshoots). Because this like filtering and phase advancing are Requiring 40 degrees of bank capability safety margin does not represent either also relevant, and should be considered would necessitate an increase in VFTO, a specific gust margin or expected when showing compliance with the which could affect the net takeoff flight piloting precision alone, the FAA does applicable requirements. The FAA is path used for clearance of distant not consider it necessary to either currently trying to harmonize its policy obstacles. Either a different departure perform a rigorous study of the effect of in these areas with those of Transport path may be necessary in the event of atmospheric gusts nor to restrict the size Canada and the JAA, and intends to add an engine failure, or takeoff weight may of the margin to a piloting test standards guidance in these areas in a future have to be reduced. The commenter objective as suggested by the revision to AC 25–7A. considers the existing rule to be commenters. The allowance and The FAA received several comments adequate, and the potential penalties magnitude of the proposed bank angle regarding the proposed addition of associated with the FAA’s proposal to margin is also consistent with typical specific maneuvering requirements as a be unjustifiable. industry practice. new § 25.143(g). One commenter This commenter also questions The maneuvering requirement at V2 suggests that the FAA should perform a whether the proposed 40 degree bank speed with one engine inoperative is rigorous study before including a angle requirement at VFTO was based on derived from the 15 degree bank angle specific gust margin in airplane a 25 degree bank angle limit used by allowed under § 121.189(f) after takeoff maneuvering requirements. The many current flight guidance systems. If plus the specified 15 degree safety commenter points out that the same so, this commenter considers such margin. At the higher speed of VFTO, atmospheric gust would have different reasoning to be flawed in that not all after the airplane has transitioned to the effects at different airspeeds, and that flight guidance systems use 25 degrees en route configuration and is farther using the same gust margin throughout as their bank angle limit. In some cases, along in the flight path, it is reasonable causes the proposed after takeoff flight guidance systems are limited to a to require additional maneuvering maneuvering requirement at V2 speed to 15 degree bank angle at the final takeoff capability appropriate to that phase of be unduly restrictive. Similarly, another speed. flight. The FAA considers an additional commenter states that the need for a 15- As a final comment on this section, 10 degrees of maneuvering capability to degree overshoot capability should first this commenter suggests that if the FAA be a reasonable expectation for a be justified by the FAA. This believes that increased bank angles are minimum capability after transitioning commenter suggests that a 5-degree appropriate for the en route flight paths, to the en route configuration and overshoot, as specified as an objective which are of longer time duration, this accelerating to the final takeoff climb for accomplishing steep turns in the need should be addressed separately speed. This same level of maneuvering ‘‘Airplane Transport Pilot and Type from the takeoff flight path capability exists on most transport Rating Practical Test Standards,’’ would requirements. However, the commenter category airplanes currently in service, be more reasonable. does not consider it necessary to do so and the FAA has determined that there Several commenters claim that the as this commenter is unaware of any is not a compelling reason to set a lower proposed maneuvering requirements, associated safety issues. minimum standard. The FAA considers particularly the one associated with the The FAA disagrees that the this same maneuvering capability (25 final takeoff speed (VFTO), are excessive maneuvering requirements specified in degrees of bank plus a 15 degree safety and would be difficult to meet without the proposed § 25.143(g) are excessive, margin) to also be appropriate for the increasing the operating speeds. One including the proposed 40 degree bank normal all-engines-operating takeoff commenter notes that for an airplane angle requirement at VFTO. These case as well as for the landing approach. equipped with a stick pusher that maneuvering requirements are For those airplane types for which the

activates near CLMAX, due to design comparable to the maneuvering proposed maneuvering requirements tolerances for the stick pusher and stall capability implied by the current would lead to an increase in VFTO, any warning systems, V2 and VFTO would regulations assuming the stall warning resulting penalty is expected to be most likely be set by the proposed margin is near the regulatory minimum. small. An increase in VFTO would only maneuvering requirements rather than Safety records and operating practices cause a penalty (in terms of a reduced the 1.13 and 1.18 factors applied to VSR, indicate that low speed maneuvering payload capability) when the takeoff respectively. Another commenter notes capability is a genuine concern. Some weight is restricted due to an obstacle that the maneuvering requirement airports necessitate close-in that must be cleared in the final takeoff associated with VFTO relates to a one- maneuvering on a regular or climb segment and cannot be avoided engine-inoperative condition of short contingency basis. Accidents and by turning or using an alternative flight duration, after which the airplane is incidents have occurred due to path procedure (e.g., retracting the flaps accelerated to the en route climb speed. windshear, icing, and high-lift device at the maximum level-off height or This commenter suggests that a anomalies. The ability to tolerate such extending the second segment to the maneuvering bank angle of 30 degrees, operational conditions can depend on takeoff thrust time limit). Recent FAA the same as specified for the takeoff the maneuvering capability at the acceptance of proposals to increase the safety speed (V2) one-engine-inoperative designated minimum operating speeds. time limit for using takeoff thrust from condition, would be more appropriate The proposed maneuvering five minutes to ten minutes should for this condition. requirements consist of the minimum further reduce the potential for This commenter further states that for bank angle capability the FAA deems economic penalties resulting from an many existing large transport category adequate for the specified regimes of increase in VFTO. airplanes, an early onset of natural stall flight combined with a further 15 In addition to receiving comments on warning results in a larger stall warning degrees of bank angle to provide a safety the minimum bank angles proposed for margin than the minimum margin margin for various operational factors. the new § 25.143(g), the FAA received required by the regulations. At VFTO, These operational factors include both comments on the footnotes these airplanes would have a potential environmental conditions accompanying the table of conditions to

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be demonstrated. A commenter notes preamble discussion states that the lower speeds that can result from the that because the trigger point of an demonstration should only have to be proposed change. The proposed changes artificial stall warning device may vary conducted down to stall warning speed were not intended to result in overall with thrust or power setting, the plus one second, which is less lower speeds. Because these comments proposed wording of footnote 1 may not demanding than the proposed new raise issues with not only speed, but cover the most critical condition for § 25.145(a). Therefore, the commenter also rudder deflection, they are determining the airplane’s maneuver suggests adding the words ‘‘In a considered beyond the scope of the margin. This commenter suggests deceleration’’ at the beginning of Notice No. 95–17 proposals, and adding the phrase ‘‘or any greater thrust § 25.145(a) and replacing the proposed § 25.177 has been adopted as proposed. or power if more critical’’ to the thrust/ reference to ‘‘the stall’’ with ‘‘one These comments will be retained for power setting references in footnotes 1 second after stall warning.’’ Guidance consideration of potential future and 3 to the table in § 25.143(g). could then be provided in AC 25–7 to rulemaking to address the concerns Although the FAA agrees with the clarify that there must be sufficient expressed by the commenters. intent of this comment, the FAA longitudinal control in this maneuver to There were many comments on the believes that the comment may stem provide confidence that pushout from proposed changes to the stall warning from a misinterpretation of the proposed an actual stall could still be requirements of § 25.207. One requirement. The condition specified in accomplished. commenter requests explicit criteria to the proposed footnote 1 to § 25.143(g) The FAA does not intend for the address whether or not a stick shaker is represents the highest thrust or power change in the reference stall speed to required to provide stall warning, or if setting for the applicable conditions of alter the basic requirement of a visual or aural warning is sufficient. weight, altitude, and temperature. If § 25.145(a), namely that the capability This same commenter also asked system design features or other relevant exists on transport category airplanes, at whether production tolerances affecting characteristics result in any condition of the specified configurations and power the stall warning margin will be weight, altitude, or temperature being settings, to pitch the nose down from addressed in AC 25–7. more critical than another, compliance any point in the stalling maneuver and The issue of what constitutes an with this requirement must be regain the trim speed. The commenter’s acceptable artificial stall warning is demonstrated for the most critical suggested change would reduce the beyond the scope of this rulemaking. condition of weight, altitude, and stringency of the regulatory However, as stated in the current temperature. This point is addressed requirement, while depending on non- § 25.207(b) (and unchanged by this further in guidance material being regulatory guidance material to rulemaking), ‘‘a visual stall warning proposed for inclusion into AC 25–7A (a provided assurances that equivalent device that requires the attention of the notice of proposed advisory circular capability is retained. crew within the cockpit is not revisions will be published in the Because the FAA cannot rely on non- acceptable by itself.’’ The FAA is Federal Register shortly after regulatory material to establish a considering future rulemaking to further publication of this final rule). capability required of the airplane, the address the issue of what constitutes an The commenter further suggests FAA has not adopted the commenter’s acceptable stall warning. Regarding stall simplifying the text of footnote 3 by suggested change. However, to improve warning tolerances, the FAA has replacing the FAA proposed text with, clarity, the words ‘‘the stall,’’ proposed proposed the inclusion of material ‘‘The critical thrust or power for all in Notice No. 95–17, have been replaced addressing stall warning system engines operating should be that which by ‘‘stall identification (as defined in tolerances into a proposed revision to in the event of an engine failure would § 25.201(d))’’ in the adopted § 25.145(a). AC 25–7A (a notice of proposed result in the minimum climb gradient In addition, techniques to show advisory circular revisions will be specified in § 25.121, or any greater compliance with this requirement published in the Federal Register thrust or power if more critical.’’ without performing a stall at maximum shortly after publication of this final Although the FAA agrees with the continuous power/thrust were included rule). This material is consistent with intent of simplifying this footnote, the in the recent issuance of AC 25–7A. the FAA positions expressed in the wording proposed in Notice No. 95–17 Consistent with the preamble discussion preamble of Notice No. 95–17. is needed to address all-engines- of Notice No. 95–17, compliance at Several commenters took issue with operating climb procedures, such as maximum continuous power may be the proposed three percent or three those used for noise abatement, that assessed by demonstrating sufficient knots stall warning margin of may use a thrust or power setting less static longitudinal stability and nose § 25.207(c). One commenter believes than that used during the takeoff. down control margin when the that the proposal represents an Therefore, the FAA does not concur deceleration is ended at least one unjustified increase in the severity of with the commenter’s suggestion. second past stall warning during a one this requirement relative to the current Section 25.143(g) is adopted as knot per second deceleration. The static rules. This commenter notes that a proposed. longitudinal stability during the requirement for stall warning to begin One commenter suggests that the maneuver and the nose down control one percent above the 1-g stall speed Notice No. 95–17 proposal to replace power remaining at the end of the would be equivalent to the current ‘‘VS’’ with ‘‘the stall’’ in § 25.145(a) is maneuver must be sufficient to assure requirement of a seven percent margin misleading and inaccurate relative to compliance with the requirement. from the minimum speed obtained in the Notice No. 95–17 supporting Two comments were received the stalling maneuver. As a discussion. The commenter believes regarding the flight test demonstrations compromise, this commenter suggests a that changing ‘‘VS’’ to ‘‘the stall’’ is to show compliance with § 25.177. Both two percent or two knot stall warning unsatisfactory for two reasons: (1) ‘‘The comments were relative to the safety margin relative to the redefined stall’’ is a vague terminology that might aspects of conducting full rudder reference stall speed. Another generally be defined by § 25.201(d), but sideslips at low airspeeds, as required commenter has a concern over possible without defining the configuration (i.e., by the current rule, although both difficulties in showing compliance with flaps, center-of-gravity position, power, commenters also noted that this the proposed arbitrary numerical margin etc.); and (2) The Notice No. 95–17 situation may be exacerbated by the for airplanes with a gradual loss of lift

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as the angle-of-attack for maximum lift idling and throttles closed’’ so that the The three knot or three percent warning is exceeded. Both of these commenters same stall warning margin would apply margin reference in the proposed request that any increase in the severity to all power and thrust settings. One § 25.207(c) would specifically quantify of this requirement: (1) Be tempered commenter suggests that to be this requirement for the conditions such that inappropriate design changes consistent with the proposed under which VSR is determined. At are not imposed for small shortfalls in § 25.103(a)(1) it is unnecessary to refer other conditions, the FAA would have meeting the strict numerical criteria; to throttles. This commenter also expected an equivalent margin to that and (2) be taken into account in the questions why the proposal states that prescribed by § 25.207(c). However, Aviation Rulemaking Advisory ‘‘§ 25.103(a)(5) does not apply’’ when there is an inherent difficulty in either Committee (ARAC) discussions of stall defining the reference stall speed to be specifying an appropriate warning warning margin when operating in icing used in connection with this margin or determining an equivalent conditions. requirement. warning margin to that specified in the Another commenter has concerns that In combination with adopting the 1- proposed § 25.207(c) for conditions the change in stall warning margin g stall speed as the appropriate other than idle thrust or power, straight requirements will reduce the margin benchmark for the low speed end of an flight, and the center-of-gravity position that is currently required and therefore airplane’s limit flight envelope, the FAA defined in the proposed § 25.103(a)(5), would not retain the existing level of considers a warning three knots or three because VSR is undefined for those safety. This commenter believes that the percent prior to reaching this speed to other conditions. proposed margin would not represent a be the minimum margin needed to In response to the comments, and to reasonable balance between providing prevent the crew from inadvertently clarify the situation regarding the the pilot with enough warning to avert slowing beyond this speed. A acceptable stall warning margin for an impending stall and providing categorical statement regarding the conditions other than those under adequate maneuvering capability at the severity of this requirement relative to which VSR is defined, the FAA has minimum operating speeds. This the current requirement cannot be made revised the proposed § 25.207(c) by commenter suggests retaining the since the effect of the change in the specifying that stall warning must begin current seven knot stall warning margin reference stall speed will vary with at least five knots or five percent, from the reference stall speed, even airplane type (and with the high lift whichever is greater, prior to the speed though the reference stall speed would device configuration on a given type). It at which the airplane is considered be redefined as the 1-g stall speed, in would, however, be inappropriate to stalled (as defined in § 25.201(d)). This order to retain the existing level of couple the existing seven percent is also the stall warning margin required safety. margin requirement relative to the by JAR–25 prior to the adoption of Another commenter considers the minimum speed reached in the stalling Change 15, and is considered to neither proposed § 25.207(c) to represent an maneuver with the redefined reference increase nor decrease the current level unjustified increase in the currently stall speed as one commenter suggests. of safety. By referencing the speed at required minimum stall warning margin The FAA does not consider the which the stall is identified for that would inhibit use of part of the proposed stall warning margin to determining the adequacy of the stall airplane flight envelope within which unduly restrict access to useable parts of warning margin, and not limiting this the airplane is controllable without risk the airplane flight envelope. Relative to requirement to specific conditions of of structural damage. The commenter windshear escape, the dynamic nature thrust or power, bank angle, or center- remarks that in windshear avoidance of windshear warrants, if anything, a of-gravity position, the adopted rule maneuvers, the likelihood of escape is larger speed margin to the stalled requires that the five knot or five maximized by flying at the minimum condition. Using current windshear percent margin must be available at all controllable airspeed. The commenter escape procedures, frequent and thrust/power settings, bank angles, and also disagrees with the statement made irregular penetrations of the stall center-of-gravity positions. in Notice No. 95–17 that a speed lower warning margin are more likely to The FAA expects this stall warning than the 1-g stall speed represents a occur. This type of trained maneuver margin to be demonstrated for the transient flight condition. The was not envisioned when the current conditions of bank angle, power, and commenter notes that in steady stall warning requirements were center-of-gravity position prescribed for climbing flight, the lift force needed to promulgated. Regarding the comment the stall demonstration tests by sustain steady flight is less than the that for climbing flight the lift force will § 25.201(a). If, however, the stall airplane weight, and for larger climb be less than the airplane’s weight, this warning margin may be affected by the angles, steady flight is sustainable at condition is irrelevant for establishing system design (e.g., a stall warning or speeds lower than the 1-g stall speed. the reference stall speed or defining a stall identification system that modifies This commenter suggests revising the reasonable stall warning margin. The the stall warning or stall identification proposed § 25.207(c) to require the stall FAA has determined that the intent of system as a function of thrust, bank warning to begin at the greater of: (1) A the proposal is sufficiently clear in this angle, angle-of-attack rate, etc.), speed higher than either one knot or one respect. compliance with the adopted § 25.207(c) percent higher than the reference stall The FAA agrees that the stall warning should be demonstrated at the most speed; or (2) seven knots or seven margin for other than idle thrust or critical conditions in terms of stall percent higher than the speed at the power settings should be addressed. The warning margin. occurrence of a stall (as defined in FAA did not intend to restrict The proposed three knot or three § 25.201(d)). consideration of the adequacy of the percent (whichever is greater) stall Other comments were received on the stall warning margin to only the idle warning margin requirement relative to proposed § 25.207(c) relative to the thrust or power condition. The general VSR is retained in § 25.207(d) as an engine thrust or power setting requirement for a stall warning with additional criterion applicable to that associated with the proposed three sufficient margin to prevent specific flight condition. The reference percent or three knot stall warning inadvertently stalling prescribed by to throttles has been removed, as has the margin. Two commenters support § 25.207(a) applies to all normal statement that the proposed removing the reference to ‘‘engines configurations and flight conditions. § 25.103(a)(5) should not apply when

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defining the reference stall speed to be § 25.207(d), as adopted, in combination The FAA concurs that detailed used in connection with this with the adopted new requirement of guidance material may be helpful to requirement. In response to the § 25.103(d) will ensure that there must ensure an appropriate and consistent commenter’s question, the reference to be a 5 knot or 5 percent stall warning demonstration of compliance with the § 25.103(a)(5) had been proposed margin relative to VSR for these proposed accelerated stall warning because the proposed definition of the airplanes. Therefore, the proposed requirement. This material will be reference stall speed would have § 25.207(d) is removed. presented in the proposed revisions to required that the center-of-gravity The stall speed margins required by AC 25–7A, which will be published in position for determining the reference the adopted §§ 25.207(c) and (d) must be the Federal Register shortly after stall speed would be that which results available in terms of calibrated airspeed. publication of this final rule. in the highest value of the reference stall Normally, test demonstrations at the The purpose of the proposed speed. Since the center-of-gravity conditions specified in § 25.201 (Stall requirement is to ensure that adequate position at which the proposed three demonstration) will be sufficient to stall warning exists to prevent an knot or three percent stall warning show compliance with these inadvertent stall under the most requirement would apply was not requirements. However, if the stall demanding conditions likely to occur in specified, it presumably would apply to warning margin for a particular airplane normal flight. The proposed conditions all center-of-gravity positions. type varies significantly with power or of 1.5g and a three knots per second Therefore, without the proposed thrust, center-of-gravity position, bank entry rate (i.e., airspeed deceleration statement, a literal interpretation of the angle, of some other characteristic, rate) correspond to the steep turn proposed requirement would have additional test conditions may be maneuver prescribed in part 121, required the stall warning speed at any necessary. Appendices E and F for pilot initial and center-of-gravity position to be three As with other part 25 requirements, proficiency training, respectively, plus knots or three percent above the stall shortfalls in demonstrating compliance some margin for error (three degrees speed evaluated at the most adverse with the literal terms of the stall more bank and a decreasing airspeed). center-of-gravity position. This was not warning margin requirements would The elevated load factor will emphasize any adverse stall characteristics, such as the intention. Any evaluation of the necessitate either a design change, an wing drop or asymmetric wing flow effect of center-of-gravity position on exemption (per § 11.25), or features that breakdown, while also investigating the stall warning margin should be would provide equivalent safety using Mach and potential aeroelastic effects based on the same center-of-gravity an alternate means of compliance (per on available lift. The proposed three position for both the stall speed and the § 21.21(b)(1)). Other rulemaking projects knots per second deceleration rate is stall warning speed. in which the stall warning margin is an The proposed wording, along with intended to result in a reasonable issue (e.g., discussions of flight in icing additional explanatory material that penetration beyond the onset of stall conditions by the ARAC) will be would have been proposed for addition warning. A 30-degree banked turn considered on their own merits. to AC 25–7A, was intended to clarify maneuver, as proposed by several of the that for center-of-gravity positions other Several commenters object to the commenters, produces a load factor of than that specified in the proposed accelerated stall warning margin only 1.15g, which the FAA does not § 25.103(a)(5), the same center-of-gravity requirement proposed as a new consider high enough to evaluate the position should be used for both the § 25.207(e). Some of the commenters effect of elevated load factor on the stall speed and the stall warning speed. claim that, in some cases, attempts to capability to prevent an inadvertent However, due to the potential for demonstrate compliance with this stall. confusion over the proposed wording, proposed requirement during flight As noted by one of the commenters, and because the explicit stall warning testing resulted in maneuvers that the the bank angle used during the speed margin prescribed by the commenters consider inappropriate for maneuver to demonstrate compliance proposed § 25.207(c) only applies to the a transport category airplane. These with this proposed requirement may conditions under which VSR is commenters provide several examples affect the airplane’s stall characteristics. determined, the proposed wording of the maneuvers they described as However, this aspect is considered regarding center-of-gravity position has inappropriate. Other commenters note secondary to the primary effect of an been removed. Instead, the center-of- that the phrase ‘‘to prevent stalling’’ elevated load factor on the stall warning gravity position specified in needs further clarification. One margin. For this reason, § 25.207(e) is § 25.103(b)(5) (re-numbered from the commenter questions the lack of a bank revised from the version published in proposed § 25.103(a)(5)) has been angle stipulation in the proposed the NPRM to prescribe a load factor included in the list of conditions for requirement and provided an analysis rather than a bank angle. An acceptable which the specific three knot or three indicating that bank angles of about 45 means of producing this load factor percent stall warning margin of the degrees have the greatest effect on would be a 48-degree banked turn in adopted § 25.207(d) applies. For other aerodynamics. This commenter also level flight. center-of-gravity positions, the claims that a prescribed load factor and As adopted, § 25.207(e) requires an acceptable stall warning margin is now deceleration rate are not simultaneously airspeed deceleration rate of greater addressed in the adopted § 25.207(c). achievable at CLMAX. The commenter than two knots per second instead of Because of the differences between suggests revising the proposed rates up to three knots per second. This naturally stalling airplanes and those § 25.207(e) to specify 30 degree banked change clarifies the intent of achieving that employ a device to abruptly push turns (for consistency with the turning a reasonable deceleration rate rather the nose down at a selected angle of flight stall characteristics demonstration than one specific value, and will result attack to identify the stall, the FAA required by § 25.201(a)) with accelerated in the intended penetration beyond the proposed that the stall warning margin rates of entry into the stall, up to the onset of stall warning. The FAA for airplanes that employ these devices greater of 1.5g load factor and 3 knots anticipates that with typical test would be required to be five knots or per second speed reduction. This techniques, requiring a deceleration rate five percent prior to the speed at which suggestion was made by other of greater than two knots per second the device activates. The application of commenters as well. will result in deceleration rates close to

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three knots per second. The power and findings, special conditions, or The reference to 1.3 VS in the current trim conditions are now specified in the exemptions, whichever is appropriate § C36.9(e)(1) had been derived from the rule in order to ensure consistent for the specific case. § 25.125 landing requirements, i.e., 1.3 application of this requirement. In addition to replacing ‘‘landing VS was interpreted to be the speed at the To clarify the meaning of the phrase screen height’’ with ‘‘50 foot height,’’ 50 foot height. Further away from the ‘‘to prevent stalling,’’ the parenthetical the words ‘‘for manual landings’’ have runway, at the point at which the expression, ‘‘(as defined in been removed from the definition of approach noise is measured (6,562 feet § 25.201(d)),’’ has been added in the ‘‘reference landing speed’’ since the from the runway threshold), the adopted § 25.207(e). Therefore, any of applicable § 25.125 landing distance airplane is likely to be at a somewhat the acceptable indications of a stall requirements make no such distinction. higher speed. Higher speeds are used applicable to stall demonstration testing Approval of automatic landing systems, during the approach to provide greater is also considered an indication that the including consideration of associated stall and controllability margins, airplane has stalled during the landing speeds and distances, is especially in the presence of winds and accelerated stall warning demonstration. addressed in FAA ACs 20–57A, 120– gusts, with the additional speed being If any of these indications of a stall 28D, and 120–29. bled off by the time the airplane is at the occur during the accelerated stall Further review of the proposed 50 foot height. As stated in the preamble warning demonstration, compliance change to § 97.3(b) indicated a potential to the amendment that added part 36 to with § 25.207(e) will not have been for confusion with respect to its the FAR, ‘‘The intent of this proposal demonstrated. application to aircraft certificated using was to require an airspeed that is highly Two commenters offered comments VS, the minimum speed in the stalling typical of normal approach airspeeds, so relative to subpart C (Structure) of part maneuver, rather than V . There is that a realistic approach speed is 25. One of these commenters suggests SR some concern that the proposed generated. The speed 1.3 VS + 10 knots that the interpretation of the stall speed replacement of 1.3 V with V may is such an airspeed and is therefore used in subpart C be undertaken S0 REF introduce terminology which is not well specified * * *’’ The ten knot urgently as part of the Harmonization understood by all potential users of the increment applied to 1.3 VS represents Work Program. The other commenter airspace system, and that information the typical approach speed at the suggests that either subpart C should be provided in some Airplane Flight approach noise measuring point. reworked to reflect the introduction of Manuals may not be consistent with the In a later amendment to part 36 V or § 25.103 should introduce SR new terminology. Therefore, as adopted, (Amendment 36–5), the FAA recognized definitions of V and V in terms of S0 S1 § 97.3(b) will continue to reference 1.3 that, for various reasons, a speed higher VSR. These comments regarding subpart C VS0 for use in those cases where VREF is than 1.3 VS may be used in establishing of part 25 are beyond the scope of this not specified. the landing distance under § 25.125. rulemaking, which is confined to the One adverse comment was received Amendment 36–5 added the words ‘‘or definition of the stall speed used for on the proposed change to § C36.9(e)(1) the speed used in establishing the airplane performance determination and of Appendix C to part 36. The approved landing distance under the handling characteristics. This commenter notes that the proposed airworthiness regulations constituting amendment does not affect the stall change could result in increasing the the type certification basis of the speeds used in subpart C for structural speed used to show compliance with airplane, whichever speed is greatest’’ to analysis. the approach noise requirements for the ‘‘1.3 VS + 10 knots’’ speed Further consideration by the FAA those cases where VREF is greater than requirement over the approach noise regarding the proposed revisions to 1.23 VSR0 (or 1.3 VS for airplanes measuring point. §§ 1.1 (Definition of reference landing certificated under the existing stall The additional 10 knot speed speed) and 97.3(b) (Definition of aircraft speed requirements). The commenter increment added to 1.3 VS was not approach category) has resulted in states that this increased speed can added to ‘‘the speed used in establishing minor changes in the adopted rule result in higher certificated noise levels. the approved landing distance under the relative to the original proposals. The The commenter objects to the increased airworthiness regulations constituting proposed definition of reference landing stringency and believes it to be an the type certification basis of the speed had used the term ‘‘landing inappropriate consequence of changing airplane.’’ The FAA has since screen height’’ to identify the point in to the 1-g stall speed reference. The determined, however, that the ten knot the approach at which the reference commenter also notes the importance of speed increment should be applied to landing speed is determined. Although arriving at harmonized criteria with the the speed used to determine the landing this term is defined in the preamble JAA for the approach speed used for distance under § 25.125, regardless of discussion of the rule proposal, it is not noise certifications. whether that speed is 1.3 VS or some defined or used elsewhere within the The FAA disagrees with the higher speed. The flightcrew does not regulations. The landing distance commenter. The proposed amendment know whether the approach speed requirements of § 25.125 specify this would have replaced the words ‘‘1.3 VS provided in their manuals is based on height as the 50 foot height, and the + 10 knots’’ with ‘‘VREF + 10 knots’’ and 1.3 VS or some higher speed and will adopted definition of reference landing removed the words ‘‘or the speed used use the same procedures and speed speed in § 1.1 has been changed to be in establishing the approved landing increments in either case. consistent with this requirement. distance under the airworthiness The FAA’s proposal would have set The preamble discussion references regulations constituting the type the speed over the approach noise approvals of steep approach operations certification basis of the airplane, measuring point at VREF +10 knots. that use a ‘‘landing screen height’’ of whichever speed is greatest.’’ The effect Since VREF is the speed used to less than the 50 foot height prescribed of the proposal would have been to determine the landing distance, a by the § 25.125 landing distance require a steady approach speed of VREF consistent speed increment would be requirements. These types of approvals + 10 knots over the approach noise applied to the speed applicable to the 50 are not the norm, however, and should measuring point during the flight test foot height, regardless of whether VREF be processed as equivalent safety measurement of approach noise levels. is determined by stall speed,

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controllability requirements, or some reviewed the corresponding ICAO 80s for most part 25 type certifications, other parameter. Standards and Recommended Practices in many cases through the Issue Paper Subsequent to the publication of and the Joint Aviation Authorities process. This rule establishes the Notice 95–17, Working Group 1 (WG1) regulations, where they exist, and has codification of this practice, and thus of the International Civil Aviation identified no differences in these adds the safety benefit of preventing Organization (ICAO) Committee on amendments and the foreign deviation from this practice. The FAA Aviation Environmental Protection regulations. has not attempted to quantify this (CAEP) recommended to the ICAO benefit. CAEP that the noise certification Regulatory Evaluation Summary The FAA also expects this rule will approach reference speed contained in Economic Evaluation, Regulatory result in added benefits in the form of Volume I of Annex 16 to the Convention Flexibility Determination, International cost savings to those affected on International Civil Aviation (the Trade Impact Assessment, and manufacturers that carry out type ICAO International Standard and Unfunded Mandates Assessment certification to both FAR and JAR Recommended Practice for Aircraft Changes to Federal regulations must requirements. Historically, U.S. Noise Certification) be changed to VREF undergo several economic analyses. manufacturers that certificate part 25 + 10 knots. The WG1 was established by First, Executive Order 12866 directs airplanes to both FAA and JAA the CAEP to provide technical guidance each Federal agency to propose or adopt requirements using 1-g stall speed regarding revisions to Annex 16, a regulation only if the agency makes a criteria have done so by working out Volume 1. The United States is a reasoned determination that the benefits separate arrangements with both member of both the ICAO CAEP and of the intended regulation justify its authorities. The FAA expects WG1. The WG1 did not view the costs. Second, the Regulatory Flexibility compliance with a single harmonized adoption of VREF + 10 knots as having Act of 1980 requires agencies to analyze FAA/JAA regulatory standard will be a significant effect on stringency. At its the economic impact of regulatory simpler and more direct than 5th meeting, which was held in January changes on small entities. Third, the compliance through separate 2001, the ICAO CAEP accepted the WG1 Trade Agreements Act (19 U.S.C. arrangements, and that cost savings will recommendation regarding adoption of section 2531–2533) prohibits agencies result. The FAA has not attempted to VREF + 10 knots. This recommendation from setting standards that create quantify this benefit. was subsequently included in unnecessary obstacles to the foreign The Estimate of Costs and Its Evolution Amendment 7 of Annex 16, Volume 1, commerce of the United States. In As noted, the FAA has accepted 1-g which was adopted by the ICAO developing U.S. standards, this Trade Council on June 29, 2001. stall speed criteria for most part 25 type Act requires agencies to consider certification projects since the mid- As a member of the ICAO Council, international standards. Where CAEP and WG1, the FAA supported the 1980s. The FAA expects this rule will appropriate, agencies are directed to use not change the substance of accepted conclusion to use VREF + 10 knots. The those international standards as the commenter has provided no support for certification practices. Thus, no more basis of U.S. standards. And fourth, the than minimal additional certification the expressed effect on stringency. The Unfunded Mandates Reform Act of 1995 concern expressed by the commenter costs will be associated with this new requires agencies to prepare a written rule. regarding the use of harmonized criteria assessment of the costs, benefits and between the FAA and JAA would be However, as certification practices other effects of proposed or final rules. and aviation technology have evolved eliminated by FAA adoption of the This requirement applies only to rules Annex 16, Amendment 7 requirement, since the mid-1980s, the costs of that include a Federal mandate on State, certification at 1-g have changed. As considering that Annex 16 is the basis local or tribal governments or the for the JAA noise certification these costs have changed, private sector, likely to result in a total manufacturers’ estimates of comparative requirements. Accordingly, the FAA expenditure of $100 million or more in adopted the Annex 16, Amendment 7 certification costs have changed; and any one year (adjusted for inflation.) FAA’s estimates of the costs associated requirement as part of Amendment 24 to In conducting these analyses, the FAA part 36, which was published in the with this rule have changed. has determined that this final rule: (1) This final rule evaluation was begun Federal Register on July 8, 2002 (67 FR Has benefits that do justify its costs; (2) 45193). in 1999. It completes the regulatory is not a ‘‘significant rulemaking’’ either evaluation process that began with Other than the changes noted above, as defined in the Executive Order or in the proposed changes to part 25 are research pursuant to a 1996 NPRM. DOT’s Regulatory Policies and Comments to the docket in response to adopted as proposed in Notice No. 95– Procedures; (3) will not have a 17. that NPRM were received in 1996. significant impact on a substantial Pursuant to this final rule evaluation, Paperwork Reduction Act number of small entities; (4) will lessen providers of previously received In accordance with the Paperwork restraints on international trade; and (5) information were asked to review, Reduction Act of 1995 (44 U.S.C. will not contain a significant clarify and update their information as 3507(d)), there are no requirements for intergovernmental or private sector necessary. Their clarifications and information collection associated with mandate. updates, together with the previous These analyses, available in the this amendment. research and analysis are the basis for docket, are summarized as follows. the conclusions developed in this final International Compatibility Economic Evaluation rule evaluation. In keeping with U.S. obligations While the costs provided in the 1996 under the Convention on International The Benefits Estimate comments were much higher than those Civil Aviation, it is FAA policy to This rule supports the existing level of the 1996 NPRM, the 1999 comply with International Civil of safety because type certification for clarifications and updates brought the Aviation Organization (ICAO) Standards part 25 airplanes based on 1-g criteria is costs developed in this final rule and Recommended Practices to the common practice, the FAA having evaluation more into line with those of maximum extent practical. The FAA has accepted 1-g stall criteria since the mid- the NPRM. Cost estimates for typical

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type certification projects that use 1-g type certification using minimum speed cannot be reduced, thus diminishing the stall speed as the reference datum have stall. This practice also is expected to current level of safety. The agency has evolved as follow: add very minor or no cost for additional not attempted to quantify either this • In 1996, the NPRM concluded that instrumentation beyond that required added benefit or the benefits already the costs of 1-g compliance differed for the type certification baseline. being received. depending upon the size of the airplane This final evaluation notes the Another additional benefit of certified. In then-current dollars, the possibility, also raised in the NPRM and improved codification is that type NPRM estimated compliance costs of in the 1999 clarifications and updates, certification to both FAR and JAR $195,000 for a type certification for large that codification of this ongoing requirements will be simpler, more part 25 airplanes. For small part 25 practice, and its consequent extension direct and consequently less costly. The airplanes, the NPRM estimate included to all U.S. manufacturers and to all part agency has not attempted to quantify a one-time cost of $70,000 for each 25 airplanes they will certificate in the this harmonization benefit. manufacturer and subsequent type future, could have an adverse impact on Because it is an improvement of the certification costs of $250,000. This marketing efforts by manufacturers. (In codification of voluntary industry final rule evaluation concludes that general, this rule reduces the practices, the FAA concludes that this neither regulatory nor practical multiplying factors used to convert rule will add little or no cost to the distinctions between small and large reference speed to minimum operational industry. The agency estimates that airplanes allow the unambiguous speeds by about 6 percent. When the affected manufacturers already grouping by size category needed to reduced multiplying factors are applied voluntarily incur costs of about support the level of economic analysis to the 1-g stall speed, which is generally $130,000 (in 1999 dollars) for each type characteristic of final rules. about 6 percent higher than minimum certification project they base on 1-g • In 1996, comments received in speed stall, the resulting minimum stall speed criteria, beyond the costs response to the NPRM gave additional operating speeds generally will result in they would incur in type certification compliance costs per type certification the same values produced by using based on minimum stall speed criteria. in then-current dollars that ranged from minimum stall speed as the reference The FAA concludes that while this $331,412 for instrumentation costs plus datum. However, variation is possible. final rule will add little or nothing to $35,029 for testing and analysis, to an This possible variation is at the heart of the safety benefits and the certification undifferentiated $1,000,000 per type assertions of marketing impact. No such costs that already result from voluntary certification project. impact is considered in this evaluation, industry practices, it does add safety • For this final rule evaluation, the for the reasons that follow: and harmonization benefits. Thus, the baseline for cost comparisons is the —The possible differences in FAA believes this rule is cost effective. estimate of the current cost of type operational speeds between type Regulatory Flexibility Determination certification using minimum stall speed certification using 1-g stall speed and as the reference datum for a typical part type certification using minimum stall The Regulatory Flexibility Act of 1980 25 airplane. Building on the NPRM, the speed are in the low single digits (RFA) establishes ‘‘as a principle of comments to the Docket, and the when expressed as speeds regulatory issuance that agencies shall clarifications and updates, this final rule —The very large number of possible endeavor, consistent with the objective evaluation estimates typical additional combinations of airplane types, of the rule and of applicable statutes, to compliance costs of about $130,000 for operational conditions, operators’ fit regulatory and informational a type certification program conducted services and airport characteristics requirements to the scale of the at 1-g for a part 25 airplane, expressed forestalls practical quantitative business, organizations, and in 1999 dollars. consideration of the possible small governmental jurisdictions subject to • During the time the FAA has been consequences noted above regulation.’’ To achieve that principle, accepting certification at 1-g, additional —Any operational consequence of the Act requires agencies to solicit and costs of instrumentation have become certification at 1-g already results consider flexible regulatory proposals small to negligible. Falling from ongoing industry practice and and to explain the rationale for their instrumentation costs and rising cannot also be considered to result actions. The Act covers a wide-range of instrumentation capability have resulted from this rule small entities, including small in acceptable test data being achieved —The possible differences in businesses, not-for-profit organizations by adding as little additional operational speeds between type and small governmental jurisdictions. instrumentation as one accelerometer to certification using 1-g stall speed and Agencies must perform a review to the test equipment required for type certification using minimum stall determine whether a proposed or final certification at minimum stall speed. speed are in the low single digits rule will have a significant economic (The estimated uninstalled cost of an when expressed as speeds impact on a substantial number of small accelerometer appropriate to this use is entities. If the determination is that it the minimal cost of $500 to $2,000, in Benefits/Costs Comparison will, the agency must prepare a 1999 dollars. Further, accelerometer and The FAA finds that this rule improves regulatory flexibility analysis as gyroscopic components already present the codification of current industry described in the Act. in the inertial navigation systems practices that have evolved over a However, if an agency determines that incorporated on modern transport period of about 15 years. These a proposed or final rule is not expected category airplanes are the fundamental practices already result in the benefits of to have a significant economic impact starting point for instrumentation the current level of safety. With one on a substantial number of small sufficient to measure a 1-g stall speed.) exception, this rule will add little or entities, section 605(b) of the 1980 act In summary, for a typical part 25 nothing to these benefits. The exception provides that the head of the agency airplane, the current industry practice of is the elimination of the possibility that may so certify and a regulatory type certification using 1-g stall as the a future part 25 airplane might not be flexibility analysis is not required. The reference datum adds a minor cost certificated based on 1-g stall speed certification must include a statement ($130,000) for flight-testing and analysis criteria. Removing this possibility providing the factual basis for this to the costs of the baseline alternative of ensures that the benefits being received determination, and the reasoning should

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be clear. For aircraft manufacturers, a ‘‘significant regulatory action.’’ This 14 CFR Part 97 small entity is one with 1,500 or fewer final rule does not contain such a Air traffic control, Airports, employees. mandate. Therefore, the assessment Navigation (air), Weather. Evaluation of this final rule in terms requirements of Title II of the Unfunded of this standard shows that no current Mandates Reform Act of 1995 do not The Amendments manufacturer of transport category apply. In consideration of the foregoing, the airplanes is a small manufacturer. Executive Order 3132, Federalism Federal Aviation Administration (FAA) Although the future entry of a small amends Chapter I of Title 14 Code of manufacturer into the business of The FAA has analyzed this final rule Federal Regulations (CFR) parts 1, 25, manufacturing transport category under the principles and criteria of and 97 as follows: airplanes is possible, such an unusual Executive Order 13132, Federalism. We single entrant could not be construed to determined that this action will not PART 1—DEFINITIONS AND equate to a ‘‘substantial number.’’ have a substantial direct effect on the ABBREVIATIONS Finally, no regulatory flexibility State, or the relationship between the analysis is required for this rule because national Government and the States, or 1. The authority citation for part 1 it adds little or nothing to the costs that on the distribution of power and continues to read as follows: otherwise would be required for type responsibilities among the various Authority: 49 U.S.C. 106(g), 40113, 44701. certification of a transport category levels of government. Therefore, we 2. Section 1.1 is amended by adding airplane by a manufacturer of any size. determined that this final rule does not new definitions in alphabetical order to Therefore the impact of this rule would have federalism implications. read as follows: not be significant whether it fell on a large or on a small manufacturer. Regulations Affecting Interstate § 1.1 General definitions. In light of these arguments, the FAA Aviation in Alaska * * * * * certifies that the rule change will not Section 1205 of the FAA Final takeoff speed means the speed have a significant economic impact on Reauthorization Act of 1996 (110 Stat. of the airplane that exists at the end of a substantial number of small entities, 3213) requires the Administrator, when the takeoff path in the en route and a regulatory flexibility analysis is modifying regulations in Title 14 of the configuration with one engine not required. CFR in a manner affecting interstate inoperative. * * * * * International Trade Impact Analysis aviation in Alaska, to consider the extent to which Alaska is not served by Reference landing speed means the The Trade Agreement Act of 1979 transportation modes other than speed of the airplane, in a specified prohibits Federal agencies from aviation, and to establish such landing configuration, at the point engaging in any standards or related regulatory distinctions as he or she where it descends through the 50 foot activities that create unnecessary considers appropriate. Because this rule height in the determination of the obstacles to the foreign commerce of the would apply to the certification of landing distance. United States. Legitimate domestic future designs of transport category * * * * * objectives, such as safety, are not airplanes and their subsequent 3. Section 1.2 is amended by adding considered unnecessary obstacles. The operation, it could, if adopted, affect new abbreviations in alphabetical order statute also requires consideration of interstate aviation in Alaska. to read as follows: international standards and where appropriate, that they be the basis for Environmental Analysis § 1.2 Abbreviations and symbols. U.S. standards. FAA Order 1050.1D defines FAA * * * * * Because this rule is a part of a actions that may be categorically VFTO means final takeoff speed. harmonization process that will result excluded from presentation of a * * * * * in a single FAA/JAA regulatory National Environmental Policy Act VREF means reference landing speed. standard, it reduces a barrier to (NEPA) environmental impact * * * * * international trade. Thus, in accordance statement. In accordance with FAA VSR means reference stall speed. with the above statute, the FAA has Order 1050.1D, appendix 4, paragraph VSR0 means reference stall speed in assessed the potential effect of this final 4(j), this rulemaking action qualifies for the landing configuration. rule and has determined that it will a categorical exclusion. VSR1 means reference stall speed in a support the Act. specific configuration. Energy Impact Unfunded Mandates Reform Act VSW means speed at which onset of The energy impact of this amendment natural or artificial stall warning occurs. The Unfunded Mandates Reform Act has been assessed in accordance with * * * * * of 1995 (the Act), enacted as Public Law the Energy Policy and Conservation Act 104–4 on March 22, 1995 is intended, (EPCA) Public Law 94–163, as amended PART 25—AIRWORTHINESS among other things, to curb the practice (42 U.S.C. 6362) and FAA Order 1053.1. STANDARDS: TRANSPORT of imposing unfunded Federal mandates It has been determined that the final CATEGORY AIRPLANES on State, local, and tribal governments. Title II of the Act requires each rule is not a major regulatory action 4. The authority citation for part 25 Federal agency to prepare a written under the provisions of the EPCA. continues to read as follows: statement assessing the effects of any List of Subjects Authority: 49 U.S.C. 106(g), 40113, 44701, Federal mandate in a proposed or final 14 CFR Part 1 44702, 44704. agency rule that may result in a $100 5. Section 25.103 is revised to read as million or more expenditure (adjusted Air transportation. follows: annually for inflation) in any one year 14 CFR Part 25 by State, local, and tribal governments, § 25.103 Stall speed. in the aggregate, or by the private sector; Aircraft, Aviation safety, Reporting (a) The reference stall speed, VSR, is a such a mandate is deemed to be a and recordkeeping requirements. calibrated airspeed defined by the

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applicant. VSR may not be less than a 1- 6. Section 25.107 is amended by text, (d) introductory text, (d)(2) and g stall speed. VSR is expressed as: revising paragraphs (b)(1) introductory (d)(3), and by adding paragraph (d)(4) to text, b(1)(ii), (b)(2) introductory text, read as follows: VCL b(2)(ii), (c)(1) and (c)(2), and by adding V ≥ MAX § 25.121 Climb: One-engine-inoperative. SR n new paragraphs (c)(3) and (g) to read as ZW follows: * * * * * where: (c) Final takeoff. In the en route § 25.107 Takeoff speeds. VCLMAX = Calibrated airspeed obtained configuration at the end of the takeoff when the load factor-corrected lift * * * * * path determined in accordance with coefficient (b) * * * § 25.111, the steady gradient of climb (1) 1.13VSR for— may not be less than 1.2 percent for two-  nW * * * * * engine airplanes, 1.5 percent for three-  ZW   qS  (ii) Turbojet powered airplanes engine airplanes and 1.7 percent for without provisions for obtaining a four-engine airplanes, at VFTO and with is first a maximum during the maneuver significant reduction in the one-engine- * * * * * prescribed in paragraph (c) of this inoperative power-on stall speed; (d) Approach. In a configuration section. In addition, when the (2) 1.08V for— SR corresponding to the normal all-engines- maneuver is limited by a device * * * * * operating procedure in which VSR for that abruptly pushes the nose down (ii) Turbojet powered airplanes with at a selected angle of attack (e.g., a this configuration does not exceed 110 provisions for obtaining a significant percent of the V for the related all- stick pusher), V may not be SR CLMAX reduction in the one-engine-inoperative engines-operating landing configuration, less than the speed existing at the power-on stall speed; and the steady gradient of climb may not be instant the device operates; * * * * * less than 2.1 percent for two-engine n = Load factor normal to the flight ZW (c)* * * airplanes, 2.4 percent for three-engine path at VCLMAX (1) V2MIN; airplanes, and 2.7 percent for four W = Airplane gross weight; (2) VR plus the speed increment engine airplanes, with S = Aerodynamic reference wing area; attained (in accordance with * * * * * and § 25.111(c)(2)) before reaching a height (2) The maximum landing weight; q = Dynamic pressure. of 35 feet above the takeoff surface; and (3) A climb speed established in (b) VCLMAX is determined with: (3) A speed that provides the (1) Engines idling, or, if that resultant maneuvering capability specified in connection with normal landing thrust causes an appreciable decrease in § 25.143(g). procedures, but not more than 1.4 VSR; stall speed, not more than zero thrust at * * * * * and the stall speed; (g) VFTO, in terms of calibrated (4) Landing gear retracted. (2) Propeller pitch controls (if airspeed, must be selected by the 10. Section 25.125 is amended by applicable) in the takeoff position; applicant to provide at least the gradient revising paragraph (a)(2) to read as (3) The airplane in other respects of climb required by § 25.121(c), but follows: (such as flaps and landing gear) in the may not be less than— condition existing in the test or (1) 1.18 VSR; and § 25.125 Landing. performance standard in which VSR is (2) A speed that provides the (a) * * * being used; maneuvering capability specified in (4) The weight used when V is § 25.143(g). (2) A stabilized approach, with a SR calibrated airspeed of V , must be being used as a factor to determine 7. Section 25.111 is amended by REF maintained down to the 50 foot height. compliance with a required revising paragraph (a) introductory text V may not be less than performance standard; to read as follows: REF (5) The center of gravity position that (i) 1.23 VSR0; § 25.111 Takeoff path. results in the highest value of reference (ii) VMCL established under stall speed; and (a) The takeoff path extends from a § 25.149(f); and standing start to a point in the takeoff (6) The airplane trimmed for straight (iii) A speed that provides the flight at a speed selected by the at which the airplane is 1,500 feet above the takeoff surface, or at which the maneuvering capability specified in applicant, but not less than 1.13VSR and § 25.143(g). not greater than 1.3V . transition from the takeoff to the en SR * * * * * (c) Starting from the stabilized trim route configuration is completed and condition, apply the longitudinal VFTO is reached, whichever point is 11. Section 25.143 is amended by control to decelerate the airplane so that higher. In addition— adding a new paragraph (g) to read as the speed reduction does not exceed one * * * * * follows: knot per second. 8. Section 25.119 is amended by § 25.143 General. (d) In addition to the requirements of revising paragraph (b) to read as follows: paragraph (a) of this section, when a * * * * * device that abruptly pushes the nose § 25.119 Landing climb: All-engines- (g) The maneuvering capabilities in a operating. down at a selected angle of attack (e.g., constant speed coordinated turn at a stick pusher) is installed, the reference * * * * * forward center of gravity, as specified in stall speed, VSR, may not be less than 2 (b) A climb speed of not more than the following table, must be free of stall knots or 2 percent, whichever is greater, VREF. warning or other characteristics that above the speed at which the device 9. Section 25.121 is amended by might interfere with normal operates. revising paragraphs (c) introductory maneuvering:

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Maneuvering Configuration Speed bank angle in a Thrust power setting coordinated turn

1 Takeoff ...... V2 30° Asymmetric WAT-Limited. 2 3 Takeoff ...... V2 + XX 40° All-engines-operating climb. 1 En route ...... VFTO 40° Asymmetric WAT-Limited. Landing ...... VREF 40° Symmetric for ¥3° flight path angle. 1 A combination of weight, altitude, and temperature (WAT) such that the thrust or power setting produces the minimum climb gradient speci- fied in § 25.121 for the flight condition. 2 Airspeed approved for all-engines-operating initial climb. 3 That thrust or power setting which, in the event of failure of the critical engine and without any crew action to adjust the thrust or power of the remaining engines, would result in the thrust or power specified for the takeoff condition at V2, or any lesser thrust or power setting that is used for all-engines-operating initial climb procedures.

12. Section 25.145 is amended by § 25.149 [Amended] corresponds to the reference stall speed revising paragraphs (a) introductory 14. Section 25.149 is amended in at maximum landing weight with flaps text, (a)(1), (b)(1), (b)(4), (b)(6), and (c) paragraph (c) introductory text by in the approach position and the introductory text to read as follows: revising the expression ‘‘1.2 VS’’ to read landing gear retracted). ‘‘1.13 V .’’ (b) * * * § 25.145 Longitudinal control. SR (4) The airplane trimmed for straight (a) It must be possible, at any point § 25.161 [Amended] flight at the speed prescribed in between the trim speed prescribed in 15. Section 25.161 is amended in § 25.103(b)(6). § 25.103(b)(6) and stall identification (as paragraphs (b), (c)(1), (c)(2), (c)(3) and * * * * * defined in § 25.201(d)), to pitch the nose (d) introductory text by revising the 20. Section 25.207 is amended by downward so that the acceleration to expression ‘‘1.4 VS1’’ to read ‘‘1.3 VSR1’’; revising paragraphs (b) and (c), and by this selected trim speed is prompt with and in paragraph (e)(3) by revising the adding new paragraphs (d), (e), and (f) 2 (1) The airplane trimmed at the trim expression ‘‘0.013 VS0 ’’ to read ‘‘0.013 to read as follows: 2 VSR0 .’’ speed prescribed in § 25.103(b)(6); § 25.207 Stall warning. * * * * * § 25.175 [Amended] * * * * * (b) * * * 16. Section 25.175 is amended: a. In (b) The warning must be furnished (1) With power off, flaps retracted, paragraphs (a)(2), (b)(1) introductory either through the inherent aerodynamic and the airplane trimmed at 1.3 VSR1, text, (b)(2) introductory text, (b)(3) qualities of the airplane or by a device extend the flaps as rapidly as possible introductory text and (c)(4) by revising that will give clearly distinguishable while maintaining the airspeed at the expression ‘‘1.4 VS1’’ to read ‘‘1.3 indications under expected conditions approximately 30 percent above the VSR1’’; of flight. However, a visual stall warning reference stall speed existing at each b. In paragraph (b)(2)(ii) by revising device that requires the attention of the instant throughout the maneuver. the expression ‘‘VMO + 1.4 VS1/2’’ to crew within the cockpit is not * * * * * read ‘‘(VMO + 1.3 VSR1)/2’’; acceptable by itself. If a warning device c. In paragraph (c) introductory text is used, it must provide a warning in (4) With power off, flaps retracted, by revising the expressions ‘‘1.1 V ’’ to each of the airplane configurations and the airplane trimmed at 1.3 V , S1 SR1 read ‘‘V ’’ and ‘‘1.8 V ’’ to read ‘‘1.7 prescribed in paragraph (a) of this rapidly set go-around power or thrust SW S1 V ’’; section at the speed prescribed in while maintaining the same airspeed. SR1 d. In paragraph (d) introductory text paragraphs (c) and (d) of this section. * * * * * by revising the expressions ‘‘1.1 VSO’’ to (c) When the speed is reduced at rates (6) With power off, flaps extended, read ‘‘VSW’’ and ‘‘1.3 VS0’’ to read ‘‘1.7 not exceeding one knot per second, stall and the airplane trimmed at 1.3 VSR1, VSR0’’; and warning must begin, in each normal obtain and maintain airspeeds between e. In paragraph (d)(5) by revising the configuration, at a speed, VSW, VSW and either 1.6 VSR1 or VFE, expression ‘‘1.4 VS0’’ to read ‘‘1.3 VSR0.’’ exceeding the speed at which the stall whichever is lower. is identified in accordance with § 25.177 [Amended] (c) It must be possible, without § 25.201(d) by not less than five knots or exceptional piloting skill, to prevent 17. Section 25.177 is amended in five percent CAS, whichever is greater. loss of altitude when complete paragraph (c) by revising the expression Once initiated, stall warning must retraction of the high lift devices from ‘‘1.2 VS1’’ to read ‘‘1.13 VSR1.’’ continue until the angle of attack is reduced to approximately that at which any position is begun during steady, § 25.181 [Amended] straight, level flight at 1.08 V for stall warning began. SR1 (d) In addition to the requirement of propeller powered airplanes, or 1.13 18. Section 25.181 is amended in paragraph (c) of this section, when the V for turbojet powered airplanes, paragraphs (a) introductory text and (b) SR1 speed is reduced at rates not exceeding with— by revising the reference to ‘‘1.2 VS’’ to read ‘‘1.13 V .’’ one knot per second, in straight flight * * * * * SR 19. Section 25.201 is amended by with engines idling and at the center-of- § 25.147 [Amended] revising paragraphs (a)(2) and (b)(4) to gravity position specified in read as follows: § 25.103(b)(5), VSW, in each normal 13. Section 25.147 is amended in configuration, must exceed VSR by not paragraphs (a) introductory text, (a)(2), § 25.201 Stall demonstration. less than three knots or three percent (c) introductory text, and (d) by revising (a) * * * CAS, whichever is greater. the expression ‘‘1.4 VS1’’ to read ‘‘1.3 (2) The power necessary to maintain (e) The stall warning margin must be VSR1.’’ level flight at 1.5 VSR1 (where VSR1 sufficient to allow the pilot to prevent

VerDate 0ct<31>2002 14:24 Nov 25, 2002 Jkt 200001 PO 00000 Frm 00017 Fmt 4701 Sfmt 4700 E:\FR\FM\26NOR2.SGM 26NOR2 70828 Federal Register / Vol. 67, No. 228 / Tuesday, November 26, 2002 / Rules and Regulations

stalling (as defined in § 25.201(d)) when cases of designed unequal braking and in paragraph (c)(2) by revising the recovery is initiated not less than one distributions. expression ‘‘1.3 VS0’’ to read ‘‘1.23 second after the onset of stall warning VSR0.’’ in slow-down turns with at least 1.5g 0. 0443WV2 KE = § 25.1325 [Amended] load factor normal to the flight path and N airspeed deceleration rates of at least 2 28. Section 25.1325 is amended in knots per second, with the flaps and where— paragraph (e) by revising the KE = Kinetic energy per wheel (ft.-lb.); landing gear in any normal position, expressions ‘‘1.3 VS0’’ and ‘‘1.8 VS1’’ to with the airplane trimmed for straight W = Design landing weight (lb.); read ‘‘1.23 V ’’ and ‘‘1.7 V ,’’ V = V /1.3 SR0 SR1 flight at a speed of 1.3 V REF SR, and with the VREF = Airplane steady landing respectively. power or thrust necessary to maintain approach speed, in knots, at the § 25.1587 [Amended] level flight at 1.3 VSR. maximum design landing weight (f) Stall warning must also be and in the landing configuration at 29. Section 25.1587 is amended by in provided in each abnormal sea level; and paragraph (b)(2) by revising the configuration of the high lift devices N = Number of main wheels with expression ‘‘VS’’ to read ‘‘VSR.’’ that is likely to be used in flight brakes. following system failures (including all PART 97—STANDARD INSTRUMENT * * * * * APPROACH PROCEDURES configurations covered by Airplane (g) In the landing case, the minimum Flight Manual procedures). speed rating of each main wheel-brake 30. The authority citation for part 97 § 25.231 [Amended] assembly (that is, the initial speed used is revised to read as follows: in the dynamometer tests) may not be Authority: 49 U.S.C. 106(g), 40103, 40106, 21. Section 25.231 is amended in more than the V used in the paragraph (a)(2) by revising the word 40113, 40114, 40120, 44502, 44514, 44701, determination of kinetic energy in 44719, 44721–44722. ‘‘altitude’’ to read ‘‘attitude’’ and by accordance with paragraph (f) of this 31. Section 97.3 is amended by revising the expression ‘‘80 percent of section, assuming that the test revising the first two sentences of VS1’’ to read ‘‘75 percent of VSR1.’’ procedures for wheel-brake assemblies paragraph (b) introductory text to read involve a specified rate of deceleration, § 25.233 [Amended] as follows: and, therefore, for the same amount of 22. Section 25.233 is amended in kinetic energy, the rate of energy § 97.3 Symbols and terms used in paragraph (a) by revising the reference absorption (the power absorbing ability procedures. ‘‘0.2 V ’’ to read ‘‘0.2 V .’’ S0 SR0 of the brake) varies inversely with the * * * * * § 25.237 [Amended] initial speed. (b) Aircraft approach category means * * * * * a grouping of aircraft based on a speed 23. Section 25.237 is amended in of VREF, if specified, or if VREF is not paragraphs (a), (b)(1), and (b)(2) by § 25.773 [Amended] specified, 1.3 VS0 at the maximum revising the reference ‘‘0.2 VS0’’ to read 25. Section 25.773 is amended in certificated landing weight. VREF, VS0, ‘‘0.2 VSR0.’’ paragraph (b)(1)(i) by revising the and the maximum certificated landing 24. Section 25.735 is amended by expression ‘‘1.6 VS1’’ to read ‘‘1.5 VSR1.’’ weight are those values as established revising paragraphs (f)(2) and (g) to read for the aircraft by the certification § 25.1001 [Amended] as follows: authority of the country of registry. 26. Section 25.1001 is amended in § 25.735 Brakes and braking systems. *** paragraphs (c)(1) and (c)(3) by revising * * * * * * * * * * the expression ‘‘1.4 VS1’’ to read ‘‘1.3 Issued in Washington, DC on November 14, (f) * * * VSR1.’’ (2) Instead of a rational analysis, the 2002. kinetic energy absorption requirements § 25.1323 [Amended] Marion C. Blakey, for each main wheel-brake assembly 27. Section 25.1323 is amended in Administrator. may be derived from the following paragraph (c)(1) by revising the [FR Doc. 02–29667 Filed 11–25–02; 8:45 am] formula, which must be modified in expression ‘‘1.3 VS1’’ to read ‘‘1.23 VSR1’’ BILLING CODE 4910–13–U

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