Airworthiness Criteria: Special Class Airworthiness Criteria for the AgustaWestland Philadelphia Corporation Model AW609 Powered-Lift, 86713-86717 [2024-25238]

Download as PDF 86713 Rules and Regulations Federal Register Vol. 89, No. 211 Thursday, October 31, 2024 This section of the FEDERAL REGISTER contains regulatory documents having general applicability and legal effect, most of which are keyed to and codified in the Code of Federal Regulations, which is published under 50 titles pursuant to 44 U.S.C. 1510. The Code of Federal Regulations is sold by the Superintendent of Documents. DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 21 [Docket No. FAA–2022–1726] Airworthiness Criteria: Special Class Airworthiness Criteria for the AgustaWestland Philadelphia Corporation Model AW609 PoweredLift Federal Aviation Administration (FAA), DOT. ACTION: Issuance of final airworthiness criteria. AGENCY: The FAA announces the special class airworthiness criteria for the AgustaWestland Philadelphia Corporation (AWPC) Model AW609 powered-lift. This document sets forth the airworthiness criteria the FAA finds to be appropriate and applicable for the powered-lift design. DATES: These airworthiness criteria are effective December 2, 2024. FOR FURTHER INFORMATION CONTACT: Richard C Snyder, Certification Coordination Section, AIR–613, Policy and Standards Division, Aircraft Certification Service, 10101 Hillwood Parkway, Fort Worth, TX 76177; telephone and fax 817–222–4486; email richard.c.snyder@faa.gov. SUPPLEMENTARY INFORMATION: SUMMARY: lotter on DSK11XQN23PROD with RULES1 Background The AWPC Model AW609 is a twoengine powered-lift with a maximum weight of 17,500 lbs., and a capacity of two crew and nine passengers. The aircraft has two ‘‘proprotors’’ instead of propellers or rotors. The AW609 design is a direct descendant of the Bell Helicopter Model BA609 certification project, which had design origins from the experimental Bell XV–15 aircraft. The FAA issued a notice of proposed airworthiness criteria for the AW609 powered-lift, which published in the VerDate Sep<11>2014 16:20 Oct 30, 2024 Jkt 265001 Federal Register on June 9, 2023 (88 FR 37805). After several changes of applicants, on February 15, 2012, AgustaWestland Tilt-Rotor Company, now AWPC, applied for a type certificate for the Model AW609. Under 14 CFR 21.17(c), an application for type certification is effective for three years, unless the FAA approves a longer period. Section 21.17(d) provides that, where a type certificate has not been issued within the time limit established under § 21.17(c), the applicant may file for an extension and update the designated applicable regulations in the type certification basis. Since the project was not certificated within the established time limit, the FAA approved a series of requests for extension by AWPC with the most recent request submitted on February 22, 2024. If the application extension is approved, the date of the updated type certification basis will change from March 31, 2021, to March 31, 2024. Discussion Powered-lift are type certificated as special class aircraft because the FAA has not yet established powered-lift airworthiness standards as a separate part of subchapter C of 14 CFR. Under the procedures in § 21.17(b), the airworthiness requirements for special class aircraft are the portions of the requirements in parts 23, 25, 27, 29, 31, 33, and 35 found by the FAA to be appropriate and applicable to the specific type design and any other airworthiness criteria found by the FAA to provide an equivalent level of safety to the existing standards. These final airworthiness criteria announce the applicable regulations and other airworthiness criteria developed for type certification of the Model AW609 powered-lift under § 21.17(b). The powered-lift has characteristics of both a rotorcraft and an airplane. It is designed to function as a helicopter for takeoff and landing, and as an airplane cruising at higher speeds than a helicopter during the enroute portion of flight operations. Accordingly, the Model AW609 certification basis contains standards from parts 23, 25, and 29, as well as other airworthiness criteria specific for a powered-lift. This certification basis includes parts 23, 25, and 29 airworthiness standards. These are part 23 at amendment 23–62, part 25 at amendment 25–135 (except PO 00000 Frm 00001 Fmt 4700 Sfmt 4700 § 25.903(a) at amendment 25–140 and § 25.1517 at amendment 25–86), and part 29 at amendment 29–55 (except § 29.1353 at amendment 29–59). The certification basis incorporates by reference existing transport category airplane and rotorcraft standards, one normal category airplane standard, Category A rotorcraft standards, optional Category B rotorcraft standards, and criteria for operation under instrument flight rules. Flight into known icing conditions (FIKI) is not being sought with the current certification; however, FIKI is included in these airworthiness criteria for future certifications. The certification basis also includes new criteria unique to the powered-lift design, designated as tiltrotor (TR) criteria. Many of these TR criteria consist of modified part 25 or 29 standards. Some include criteria that combine existing parts 23, 25, and 29 standards, as the maximum weight of the Model AW609 exceeds the weight for normal category rotorcraft and most part 23 category airplanes, but its passenger seating is less than that of a transport category airplane or a transport category rotorcraft. The FAA also developed TR criteria because no existing standard captures the poweredlift’s transitional flight modes (during flight, the powered-lift nacelle rotates the proprotor system from providing vertical lift to horizontal propulsion). The TR criteria also contain definitions specific for the powered-lift, such as flight modes, configurations, speeds, and terminology (‘‘flaperon’’ instead of ‘‘aileron’’ or ‘‘flap;’’ ‘‘proprotor’’ instead of ‘‘rotor’’ or ‘‘propeller’’). For example, while existing parts 25 and 29 standards for passenger emergency exits include a size classification (types I, II, III, IV) depending on the passenger seating capacity and other factors, the certification basis has a TR with criteria for the specific type of passenger emergency exit that is part of the design of the Model AW609. Another example involves fatigue evaluation. Part 25 contains requirements such as a limit of validity (LOV) on airframe fatigue for pressurized fuselages, which are not in part 29. Instead, fatigue evaluation in part 29 includes a composite structures fatigue rule, due to the more extreme fatigue environment of rotorcraft. For small airplanes, part 23, amendment E:\FR\FM\31OCR1.SGM 31OCR1 86714 Federal Register / Vol. 89, No. 211 / Thursday, October 31, 2024 / Rules and Regulations lotter on DSK11XQN23PROD with RULES1 23–48, added a composite airframe evaluation requirement for bonded joints, which is included in agency compliance guidance for parts 25 and 29 but not required by a specific regulation (the safety requirement is complied with through other broad existing regulations in those parts). Since the Model AW609 has a pressurized fuselage, the FAA developed TR criteria to include the LOV requirement. The certification basis incorporates by reference the part 29 composite rotorcraft structures fatigue rule, TR criteria to include the composite bonding requirements from part 23, as well as TR criteria to include fatigue requirements for elastomeric primary structural elements. The new requirements specific to the AWPC Model AW609 in the proposed airworthiness criteria used a ‘‘TR.xxxx’’ section-numbering scheme. Summary of Changes From the Proposed Airworthiness Criteria Based on comments received, these final airworthiness criteria reflect the following changes, in addition to others as explained in more detail in the Discussion of Comments section: • Added § 29.1547 to the final airworthiness criteria for the case where a magnetic compass is installed. • Revised these final airworthiness criteria to provide clarification on future certification for FIKI conditions. • Clarified statements about TR.45 applicability. • Revised proposed TR.575 to account for the unique nature and operating environment of elastomeric principle structural elements (PSEs). • Updated § 25.775 to clarify that the reference to § 25.335(a) is replaced with TR.335(a) for the purposes of these airworthiness criteria. • Did not include § 25.875 and updated TR.875 in these final airworthiness criteria to prevent confusion between the terms propeller and proprotor, thereby combining proposed TR.875 and § 25.875, which call out requirements for buffeting, proprotor (propeller), and other rotating components. Accordingly, TR.875 in these final airworthiness criteria addresses both proposed TR.875 and § 25.875. • Revised the incorporation by reference of § 29.1521 to reflect that the reference to § 29.1509(c) is replaced with TR.1509(c) since § 29.1509 is not part of the type certification basis for the Model AW609. • Specified the amendment level for § 25.1517 to be 25–86. • Revised these airworthiness criteria to remove § 25.1353 and include § 29.1353 at amendment 29–59 for VerDate Sep<11>2014 16:20 Oct 30, 2024 Jkt 265001 electrical wiring protection due to recent amendments to part 29. Addition of Position Light TRs After the FAA issued the notice of proposed airworthiness criteria for public comment, AWPC presented a forward left and right position light design that would not meet the prescriptive regulatory requirements defined under §§ 29.1385–29.1395. In general terms, the existing requirements define the use of a single left and a single right forward-looking position light. Due to the AW609 configuration, AWPC proposed using multiple light sources for each forward position light providing lighting at a level comparable to the part 29 lighting requirements. The FAA developed TR.1385, TR.1387, TR.1389, TR.1391, TR.1393, and TR.1395 to establish the same level of safety to §§ 29.1385, 29.1387, 29.1389, 29.1391, 29.1393, and § 29.1395 to address the non-traditional configuration of the AW609 poweredlift’s position lights. These TRs modified the language in certain part 29 sections to allow for a group of forward position lights to be installed on each side of the aircraft. Discussion of Comments The FAA received responses from six commenters including: Overair, Inc (Overair), Parker Lord Corporation (Parker Lord), Advanced Air Mobility Institute, Transport Canada, and two individual commenters. Subpart A—General The FAA proposed criteria that adopted existing and developed definitions and abbreviations specifically for the Model AW609 powered-lift under subpart A. The FAA received and reviewed comments from Transport Canada and Overair regarding subpart A of the proposed airworthiness criteria. Transport Canada requested the FAA revise TR.10(c) to use the phrase ‘‘flightdeck’’ instead of ‘‘cockpit’’ for consistency with TR.1322. The FAA concurs and has revised TR.10(c) to use the term ‘‘flightdeck.’’ Transport Canada requested the FAA revise TR.11 by adding a statement that abbreviations in these criteria apply in addition to the abbreviations in 14 CFR 1.2. The FAA does not agree with Transport Canada’s request because 14 CFR part 1.2 abbreviations are applicable unless specifically addressed as not being applicable in the certification basis. Overair stated that ‘‘VMIN’’ as defined in TR.11(c) and ‘‘minimum safe speed’’ as defined in other previously issued PO 00000 Frm 00002 Fmt 4700 Sfmt 4700 powered-lift special class airworthiness criteria would cause confusion between the two terms. The FAA disagrees with Overair. The airworthiness criteria for the AW609 are a special class certification basis and as such, the requirements are specific for this aircraft rather than generally applicable. In addition, the development of the AW609 certification basis predates the use of performance-based rules, which is the approach generally used for other special class powered-lift or similar aircraft. Subpart B—Flight The FAA proposed criteria that adopted existing regulations from subpart B of parts 23, 25, and 29, as well as developed criteria specifically for the Model AW609 powered-lift . Subpart B covers a wide range of flight criteria including performance, controllability, trim, stability, and stalls. The FAA received and reviewed comments from Overair regarding subpart B of the proposed airworthiness criteria. Overair requested the FAA clarify the safety intent of TR.45 related to the hovering ceiling given the differences in airworthiness criteria proposed for different powered-lift types. The FAA acknowledges Overair’s request. TR.45 is general performance for Category A aircraft. The FAA developed these airworthiness criteria for the AW609 for guaranteed performance that would integrate all aircraft flight modes defined in TR.10 and HTR.45 including hover. TR Appendix H—Category B Performance defines Category B performance and HTR.45 addresses general performance determination. Overair requested the FAA justify the climb performance identified in TR.67. Specifically, Overair requested the FAA explain why § 29.67(a)(1) was not adopted for the first takeoff segment and explain the rationale for adopting part 25 fixed-wing OEI minimum climb gradient criteria for this powered-lift special class aircraft. Finally, Overair inquired whether these performance requirements will provide the same level of safety when operating out of heliports and/or vertiports. The FAA acknowledges Overair’s comment. The FAA determined § 29.67(a)(1), which establishes climb performance at 200 ft, was inappropriate for a transport category powered-lift such as the AW609. In addition, the FAA did not adopt part 25 fixed-wing OEI climb requirements for the AW609. Rather, the FAA established different takeoff flight paths for ground-level heliports under TR.59 and elevated heliports under TR.60 that do not exist E:\FR\FM\31OCR1.SGM 31OCR1 lotter on DSK11XQN23PROD with RULES1 Federal Register / Vol. 89, No. 211 / Thursday, October 31, 2024 / Rules and Regulations under part 25. The takeoff flight path under TR.59 and TR.69 utilizes the performance established under TR.67 to ensure positive engine out climb performance from the surface to 1500 ft above ground level, for different segments. Overair requested the FAA clarify why a stall speed has been adopted for the AW609 as opposed to the ‘‘minimum safe speed’’ in other powered-lift special class airworthiness criteria. The FAA acknowledges Overair’s comment. The AW609 is a § 21.17(b) special class certification basis aircraft and the airworthiness criteria are specific to this aircraft. Unlike other § 21.17(b) powered-lift, the AW609 certification basis did not use performance-based criteria. There are differences between performance-based and prescriptive criteria. Conversionmode minimum safe speed is covered elsewhere in the AW609 airworthiness criteria; in the AW609 airworthiness criteria, airplane-mode (wing-borne) minimum safe speed is covered in TR.103, 201, 203, and 207. Conversionmode (Semi-thrust borne) minimum safe speed is covered in TR.38 and 143. While the airworthiness criteria for the AW609 may be different from the airworthiness criteria for other poweredlift, the safety intent is the same with regards to stall and minimum speeds. Overair requested the FAA explain why the wind velocity requirement, from all azimuths, has been increased from ‘‘at least 17 knots’’ in § 29.143(c) to 20 knots. The FAA acknowledges Overair’s comment. The AW609, as a special class aircraft, is a transport category aircraft and its certification basis includes appropriate requirements from both parts 25 and 29. Section 25.237(a)(1) requires ‘‘a 90-degree cross component of wind velocity, demonstrated to be safe for takeoff and landing, . . . [that] must be at least 20 knots . . .’’ The FAA determined that § 29.143(c) and (d)’s requirements of at least 17 knots all azimuth capability could provide a controllability gap for the AW609 when attempting to land or takeoff; as such the FAA adopted 20 knots to maintain consistency with transport aircraft requirements for specific applicability to the AW609. This approach is consistent with the draft ‘‘Interim Airworthiness Criteria for Powered-Lift Transport Category Aircraft,’’ dated July 1988. The FAA received several comments from Overair on the topics of flight performance and characteristics, and Overair requested an explanation as to why the FAA adopted older, nonperformance-based criteria. The FAA establishes the minimum safety VerDate Sep<11>2014 16:20 Oct 30, 2024 Jkt 265001 standards without dictating designs. Manufacturers are free to choose the design strategy that suits their poweredlift, as long as these designs meet a minimum accepted safety standard. The FAA received multiple comments from Overair regarding the stability criteria proposed in TR.173 (static longitudinal stability), TR.175 (demonstration of static longitudinal stability), and TR.177 (static lateraldirectional stability). Overair asked for clarification as to why proposed TR.173, TR.175, and TR.177 include stability requirements from the 1960’s instead of using recent special conditions for part 25 aircraft equipped with a fullauthority electronic flight control system. Overair requested the FAA incorporate more current airworthiness standards for fly-by-wire technology into the AW609 certification basis. The FAA does not concur with Overair’s request to revise TR.173, TR.175, and TR.177 to incorporate recent special conditions for fly-by-wire technology. The recent fly-by-wire special conditions were considered in TR.173, TR.175, and TR.177. The commenter’s assumption, that the recent special conditions were not considered for the TRs, is incorrect. Overair also inquired as to why proposed TR.181(a)(1) and TR.181(a)(2) (free and fixed position dynamic stability criteria, respectively) were included in the airworthiness criteria for an aircraft equipped with an irreversible electronic flight control system. Overair requested the FAA not adopt proposed TR.181(a)(1) and TR.181(a)(2) in the final airworthiness criteria. The FAA does not concur with Overair’s request to not adopt proposed TR.181(a)(1) and TR.181(a)(2) in the final airworthiness criteria. The FAA determined that evaluation of free and fixed flight control characteristics is necessary even if an aircraft has an irreversible electronic flight control system. Subpart C—Structure and Strength The FAA proposed criteria that adopted existing regulations from subpart C of parts 25 and 29, as well as developed criteria specifically for the AW609. Subpart C covers a wide range of strength criteria including flight loads, control surface loads, emergency landing conditions, and fatigue evaluations. The FAA received and reviewed comments from Parker Lord and one individual commenter. Parker Lord requested the FAA revise the definition of a Primary Structural Element (PSE). Parker Lord also recommended the FAA change the qualification and certification of PO 00000 Frm 00003 Fmt 4700 Sfmt 4700 86715 elastomeric PSEs from physical and static strength attributes to material functionality and the dynamic response within the design requirements of the rotor system. The FAA agrees with Parker Lord’s requests and has revised the language in final TR.575 to use the designed dynamic response of the material as compliance criteria instead of traditional static loading, deformation, and fatigue for compliance criteria. An individual commenter suggested the AW609 may become unstable in a windmilling condition and may develop whirl flutter. The commenter stated the aircraft should be tested for stability in this situation and if necessary given procedures and limitations. The commenter also stated that if the system design prevents windmilling, there should be backup systems and procedures. FAA acknowledges the commenter’s concern. Windmilling impact on aircraft stability, including any impact on whirl flutter, is already evaluated under § 25.629 and TR.629, therefore, no additional changes are deemed necessary to those airworthiness criteria. Subpart D—Design and Construction The FAA proposed criteria that adopted existing regulations from subpart D of parts 25 and 29, as well as developed criteria specifically for the Model AW609 powered-lift. Subpart D covers a wide range of design and construction criteria including criteria covering rotors, control systems, landing gear, and personnel and cargo accommodations. The FAA received and reviewed comments from Overair and Transport Canada regarding subpart D of the proposed airworthiness criteria. Transport Canada requested the FAA specify which paragraphs of § 25.335 and TR.335 the FAA is referring to in the reference to § 25.775 in the proposed airworthiness criteria. The FAA has revised the reference to § 25.775 in the final airworthiness criteria to indicate that § 25.335(a) is replaced with TR.335(a). Transport Canada requested the FAA add § 25.865 to the final airworthiness criteria because that regulation addresses fire protection requirements for the engine mounting structure and engine attachment points. The FAA does not agree with Transport Canada’s request. Section 29.861(a) is included in the final airworthiness criteria, and uses the term ‘‘structure,’’ which includes engine mounts as indicated by the example in the guidance material of AC 29.861. As a result, compliance with § 29.861(a) must also address engine E:\FR\FM\31OCR1.SGM 31OCR1 lotter on DSK11XQN23PROD with RULES1 86716 Federal Register / Vol. 89, No. 211 / Thursday, October 31, 2024 / Rules and Regulations mounting structure and engine attachment points. Applying § 29.861(a) is sufficient for this powered-lift, and requiring compliance to § 25.865 is not necessary. AC 29–2C ‘‘Certification of Transport Category Rotorcraft’’ and AC 29.861 ‘‘Fire Protection of Structure, Controls, and Other Parts’’ provide guidance for engine mounts and fire protection requirements. Transport Canada stated that § 25.867 does not define clearly what surfaces to consider as ‘‘rear of the nacelles’’ and requested the FAA clarify the intent with a figure to define the envelope and boundaries radially and axially. The FAA does not agree with Transport Canada’s request to provide a figure as this figure is defined in the project specific methods of compliance to § 25.867. Transport Canada requested a rationalization of the FAA’s exception of § 25.869(a)(3) from the proposed airworthiness criteria and requested the FAA include § 25.869(a)(3) in the final airworthiness criteria. Additionally, the commenter provided wording for § 25.869(a)(3) from amendment 25–113 even though the current amendment is 25–123, which has different language. The FAA does not concur with Transport Canada’s request to include § 25.869(a)(3) at either amendment level in the final airworthiness criteria as the airworthiness criteria already contain criteria such as § 29.1301, TR.1309, and § 29.1353 that are intended to address the same requirements as those covered by the various part 25 wiring and EWIS requirements, including § 25.869(a)(3). Overair commented that the inclusion of both § 25.675(a) and § 29.675(a) in the proposed airworthiness criteria was confusing and requested the FAA not make § 25.675(a) applicable to the AW609 because § 29.675(a) is also applicable. The FAA does not concur with this request. Both regulations need to be included in the final airworthiness criteria because the AW609 operates in both helicopter and airplane modes including the conversion mode. The AW609 aircraft control is affected by rotor collective and cyclic pitch, conventional airplane control surfaces (elevator, flaperons), and nacelle tilt; traditional helicopter-type pilot controls in the cockpit provide aircraft control in pitch, roll, and yaw axes. Overair requested the FAA not adopt § 25.875 from the proposed airworthiness criteria and reword TR.875 to prevent confusion. The FAA concurs with this request and has revised the final airworthiness criteria to not adopt § 25.875 and reworded TR.875 to reflect the use of ‘‘proprotors’’ VerDate Sep<11>2014 16:20 Oct 30, 2024 Jkt 265001 instead and of propellers to reflect TR.10(o) terminology. Subpart G—Operating Limitations and Information Subpart E—Powerplant The FAA proposed criteria that adopted existing regulations from subpart G of parts 25 and 29, as well as developed criteria specifically for the Model AW609 powered-lift. Subpart G covers a wide range of operating limitations and information criteria including airspeed, markings and placards, indicators, and flight manuals. The FAA received and reviewed comments from Transport Canada regarding subpart G of the proposed airworthiness criteria. Transport Canada requested the FAA revise the reference to § 25.1585(a)(8) in § 25.1517 to read ‘‘§ 25.1585(a)(3)’’ and explained that § 25.1585(a)(8) does not exist.’’ The FAA acknowledges Transport Canada’s request; however, the reference to § 25.1585(a)(8) is correct. The FAA revised the final airworthiness criteria to indicate that the criteria includes § 25.1517, Rough air speed, VRA is at amendment 25–86, which contains (a)(8). Transport Canada requested the FAA revise the reference to § 29.1509 and TR.1509 in § 29.1521 to include the appropriate paragraphs. The FAA concurs and revised the reference to § 29.1509 and TR.1509 to indicate that paragraph (c) is the appropriate paragraph. Transport Canada requested the FAA add ‘‘§ 29.1547 Magnetic direction indicator. (a)–(d) [Applicable to AW609]’’ to the airworthiness criteria and, if the FAA agrees, then also add a reference to § 29.1547 in TR.1501(b). The FAA concurs with adding § 29.1547 to these final airworthiness criteria and notes that § 29.1327 is the requirement for a magnetic compass and § 29.1547 is the requirement for a calibration card if a compass is installed. In lieu of a magnetic compass, § 25.1303 and TR.1303 allow for direction indicators (gyroscopically stabilized, magnetic or non-magnetic). The FAA proposed criteria that adopted existing regulations from subpart E of parts 25 and 29, as well as developed criteria specifically for the Model AW609 powered-lift. Subpart E covers a wide range of powerplant criteria including rotor drive systems, fuel systems, oil systems, and cooling and exhaust systems. The FAA received and reviewed comments from Transport Canada and one individual commenter regarding subpart E of the proposed airworthiness criteria. Transport Canada requested the FAA revise proposed TR.963 to remove the phrase ‘‘for compliance with’’ and replace it with ‘‘in addition to.’’ FAA does not concur with Transport Canada’s request. The requested change would increase the testing requirements for flexible fuel tank bladders in a way that is not intended. Transport Canada requested the FAA rationalize the exception of § 25.1203(h) from the proposed airworthiness criteria and to include § 25.1203(h) in the final airworthiness criteria. The FAA does not concur with the request to include § 25.1203(h) in the final airworthiness criteria as the airworthiness criteria already contain criteria such as § 29.1301, TR.1309, and § 29.1353 that are intended to address similar requirements as those covered by the various part 25 EWIS requirements, including § 25.1203(h). The FAA received several comments with no specific requested changes to the proposed airworthiness criteria from an individual on several aspects regarding FIKI, icing protection, and inadvertent icing encounters. The commenter inquired as to whether the AW609 has any relief from the subpart E powerplant-related requirements of normal FIKI certification other than having no subpart B testing with ice shapes and the relief of limited exposure time. The commenter also inquired as to whether the flight manual limitation that ‘‘the pilot is prohibited from flight into known or forecast icing’’ reduces or eliminates any of the other subpart E requirements for the AW609 that are normally included in a FIKI certification. The FAA acknowledges the commenter’s questions: the powerplant icing requirements are applicable per TR.1093, regardless of the aircraft’s FIKI status. PO 00000 Frm 00004 Fmt 4700 Sfmt 4700 General Comments The FAA received comments on the proposed criteria that were not specific to any subpart from The Advanced Air Mobility Institute, Transport Canada, and one individual commenter. Transport Canada made several comments concerning the structure and formatting of the airworthiness criteria document. Transport Canada further stated that the airworthiness criteria as written references many requirements instead of writing the actual text for the airworthiness criteria. Transport Canada suggested the FAA write the actual text for airworthiness criteria throughout the E:\FR\FM\31OCR1.SGM 31OCR1 lotter on DSK11XQN23PROD with RULES1 Federal Register / Vol. 89, No. 211 / Thursday, October 31, 2024 / Rules and Regulations document to make explicit the text agreed to when these airworthiness criteria are finalized. The FAA disagrees, because the 14 CFR regulations listed in the airworthiness criteria for the AW609 are incorporated into the criteria by referencing the existing rule. Transport Canada stated that the formula in proposed TR.725 Limit drop test, paragraph (d), is incomplete. The FAA disagrees with Transport Canada. The formula is correctly stated in the proposed criteria, and matches the formula suggested by the commenter. Transport Canada stated the heading for proposed TR.103 Stall SPEED is incorrect and that the term ‘‘SPEED’’ should be lower case and in bold text. The FAA agrees with Transport Canada and has corrected the heading in TR.103 in the final airworthiness criteria. Transport Canada requested the FAA explain why §§ 25.1701–25.1733 for an EWIS were not included in the proposed airworthiness criteria and requested the FAA add §§ 25.1701– 25.1733. The FAA does not concur with Transport Canada’s request to include §§ 25.170–25.1753 in the final airworthiness criteria as the FAA updated the final airworthiness criteria to replace § 25.1353 with § 29.1353 due to the recent addition of amendment 29–59 which introduced a part 29 safety target for electrical wiring. The final airworthiness criteria also contain § 29.1301, and TR.1309 which, in addition to § 29.1353, address similar requirements to those covered by the referenced part 25 EWIS and energy storage requirements. Transport Canada requested the FAA clarify whether part 34, Fuel Venting and Exhaust Emission Requirements For Turbine Engine Powered Airplanes, is applicable to the AW609, either to the engine or aircraft, as fuel venting can be influenced by the engine’s installation effects. The FAA acknowledges Transport Canada’s concern. The AW609 uses the PT6C–67A, which is a turboshaft engine. Part 34 does not apply to turboshaft engines. As long as the AW609 continues to use a turboshaft engine, part 34 will not be applicable. Transport Canada requested the FAA clarify whether part 38, Airplane Fuel Efficiency Certification is applicable to the AW609. The AW609 certification basis precedes the promulgation of 14 CFR part 38, and thus part 38 is not applicable to the AW609. The Advanced Air Mobility Institute recommended the FAA update and expand the airworthiness criteria for the Model AW609 powered-lift to require the implementation of a mandatory safety management system (SMS), VerDate Sep<11>2014 16:20 Oct 30, 2024 Jkt 265001 86717 designated as TR criteria. The FAA does acknowledge the value of implementation of a proactive SMS system. However, implementation of SMS is beyond the scope of this present effort to designate the applicable airworthiness criteria for this poweredlift. DEPARTMENT OF TRANSPORTATION Applicability RIN 2120–AA64 These airworthiness criteria, established under the provisions of § 21.17(b), are applicable to the AWPC Model AW609 powered-lift. Should AWPC apply at a later date for a change to the type certificate to include another model, these airworthiness criteria would apply to that model as well, provided the FAA finds them appropriate in accordance with the requirements of subpart D to part 21. Airworthiness Directives; Various Helicopters Conclusion This action affects only certain airworthiness criteria for the AWPC Model AW609 powered-lift. It is not a standard of general applicability. Authority Citation The authority citation for these airworthiness criteria is as follows: Authority: 49 U.S.C. 106(g), 40113, and 44701–44702, 44704. Airworthiness Criteria Pursuant to the authority delegated to me by the Administrator, the following airworthiness criteria are issued as part of the type certification basis for the AgustaWestland Philadelphia Corporation Model AW609 powered-lift. You may view the final airworthiness criteria on the internet at www.regulations.gov in Docket No. FAA–2022–1726. Issued in Kansas City, Missouri, on October 25, 2024. Patrick R. Mullen, Manager, Technical Policy Branch, Policy and Standards Division, Aircraft Certification Service. [FR Doc. 2024–25238 Filed 10–30–24; 8:45 am] BILLING CODE 4910–13–P PO 00000 Frm 00005 Fmt 4700 Sfmt 4700 Federal Aviation Administration 14 CFR Part 39 [Docket No. FAA–2024–1004; Project Identifier AD–2023–01058–R; Amendment 39–22866; AD 2024–20–07] Federal Aviation Administration (FAA), DOT. ACTION: Final rule. AGENCY: The FAA is adopting a new airworthiness directive (AD) for various helicopters modified by certain supplemental type certificates (STCs) that approve the installation of an emergency float kit or an emergency float with a liferaft kit. This AD was prompted by the results of an accident investigation and subsequent reports of difficulty pulling the emergency float kit activation handle installed on the pilot cyclic. This AD requires repetitively inspecting the pull force on the float activation handle and for certain model helicopters, this AD also requires and replacing certain part-numbered float inflation reservoirs (reservoirs) and pull cable assemblies (cables) with other part-numbered reservoirs and cables. Finally, this AD prohibits installing certain part-numbered reservoirs and cables on specific helicopters. The FAA is issuing this AD to address the unsafe condition on these products. DATES: This AD is effective December 5, 2024. The Director of the Federal Register approved the incorporation by reference of certain publications listed in this AD as of December 5, 2024. ADDRESSES: AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA–2024–1004; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this final rule, any comments received, and other information. The address for Docket Operations is U.S. Department of Transportation, Docket Operations, M–30, West Building Ground Floor, Room W12–140, 1200 New Jersey Avenue SE, Washington, DC 20590. Material Incorporated by Reference: • For Dart Aerospace material identified in this AD, contact Dart Aerospace, LTD., 1270 Aberdeen Street, Hawkesbury, ON, K6A 1K7, Canada; phone: 1–613–632–5200; fax: 1–613– 632–5246; website: dartaero.com. SUMMARY: E:\FR\FM\31OCR1.SGM 31OCR1

Agencies

[Federal Register Volume 89, Number 211 (Thursday, October 31, 2024)]
[Rules and Regulations]
[Pages 86713-86717]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-25238]



========================================================================
Rules and Regulations
                                                Federal Register
________________________________________________________________________

This section of the FEDERAL REGISTER contains regulatory documents 
having general applicability and legal effect, most of which are keyed 
to and codified in the Code of Federal Regulations, which is published 
under 50 titles pursuant to 44 U.S.C. 1510.

The Code of Federal Regulations is sold by the Superintendent of Documents. 

========================================================================


Federal Register / Vol. 89, No. 211 / Thursday, October 31, 2024 / 
Rules and Regulations

[[Page 86713]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 21

[Docket No. FAA-2022-1726]


Airworthiness Criteria: Special Class Airworthiness Criteria for 
the AgustaWestland Philadelphia Corporation Model AW609 Powered-Lift

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Issuance of final airworthiness criteria.

-----------------------------------------------------------------------

SUMMARY: The FAA announces the special class airworthiness criteria for 
the AgustaWestland Philadelphia Corporation (AWPC) Model AW609 powered-
lift. This document sets forth the airworthiness criteria the FAA finds 
to be appropriate and applicable for the powered-lift design.

DATES: These airworthiness criteria are effective December 2, 2024.

FOR FURTHER INFORMATION CONTACT: Richard C Snyder, Certification 
Coordination Section, AIR-613, Policy and Standards Division, Aircraft 
Certification Service, 10101 Hillwood Parkway, Fort Worth, TX 76177; 
telephone and fax 817-222-4486; email [email protected].

SUPPLEMENTARY INFORMATION:

Background

    The AWPC Model AW609 is a two-engine powered-lift with a maximum 
weight of 17,500 lbs., and a capacity of two crew and nine passengers. 
The aircraft has two ``proprotors'' instead of propellers or rotors. 
The AW609 design is a direct descendant of the Bell Helicopter Model 
BA609 certification project, which had design origins from the 
experimental Bell XV-15 aircraft.
    The FAA issued a notice of proposed airworthiness criteria for the 
AW609 powered-lift, which published in the Federal Register on June 9, 
2023 (88 FR 37805).
    After several changes of applicants, on February 15, 2012, 
AgustaWestland Tilt-Rotor Company, now AWPC, applied for a type 
certificate for the Model AW609. Under 14 CFR 21.17(c), an application 
for type certification is effective for three years, unless the FAA 
approves a longer period. Section 21.17(d) provides that, where a type 
certificate has not been issued within the time limit established under 
Sec.  21.17(c), the applicant may file for an extension and update the 
designated applicable regulations in the type certification basis. 
Since the project was not certificated within the established time 
limit, the FAA approved a series of requests for extension by AWPC with 
the most recent request submitted on February 22, 2024. If the 
application extension is approved, the date of the updated type 
certification basis will change from March 31, 2021, to March 31, 2024.

Discussion

    Powered-lift are type certificated as special class aircraft 
because the FAA has not yet established powered-lift airworthiness 
standards as a separate part of subchapter C of 14 CFR. Under the 
procedures in Sec.  21.17(b), the airworthiness requirements for 
special class aircraft are the portions of the requirements in parts 
23, 25, 27, 29, 31, 33, and 35 found by the FAA to be appropriate and 
applicable to the specific type design and any other airworthiness 
criteria found by the FAA to provide an equivalent level of safety to 
the existing standards. These final airworthiness criteria announce the 
applicable regulations and other airworthiness criteria developed for 
type certification of the Model AW609 powered-lift under Sec.  
21.17(b).
    The powered-lift has characteristics of both a rotorcraft and an 
airplane. It is designed to function as a helicopter for takeoff and 
landing, and as an airplane cruising at higher speeds than a helicopter 
during the enroute portion of flight operations. Accordingly, the Model 
AW609 certification basis contains standards from parts 23, 25, and 29, 
as well as other airworthiness criteria specific for a powered-lift.
    This certification basis includes parts 23, 25, and 29 
airworthiness standards. These are part 23 at amendment 23-62, part 25 
at amendment 25-135 (except Sec.  25.903(a) at amendment 25-140 and 
Sec.  25.1517 at amendment 25-86), and part 29 at amendment 29-55 
(except Sec.  29.1353 at amendment 29-59). The certification basis 
incorporates by reference existing transport category airplane and 
rotorcraft standards, one normal category airplane standard, Category A 
rotorcraft standards, optional Category B rotorcraft standards, and 
criteria for operation under instrument flight rules. Flight into known 
icing conditions (FIKI) is not being sought with the current 
certification; however, FIKI is included in these airworthiness 
criteria for future certifications.
    The certification basis also includes new criteria unique to the 
powered-lift design, designated as tiltrotor (TR) criteria. Many of 
these TR criteria consist of modified part 25 or 29 standards. Some 
include criteria that combine existing parts 23, 25, and 29 standards, 
as the maximum weight of the Model AW609 exceeds the weight for normal 
category rotorcraft and most part 23 category airplanes, but its 
passenger seating is less than that of a transport category airplane or 
a transport category rotorcraft. The FAA also developed TR criteria 
because no existing standard captures the powered-lift's transitional 
flight modes (during flight, the powered-lift nacelle rotates the 
proprotor system from providing vertical lift to horizontal 
propulsion). The TR criteria also contain definitions specific for the 
powered-lift, such as flight modes, configurations, speeds, and 
terminology (``flaperon'' instead of ``aileron'' or ``flap;'' 
``proprotor'' instead of ``rotor'' or ``propeller'').
    For example, while existing parts 25 and 29 standards for passenger 
emergency exits include a size classification (types I, II, III, IV) 
depending on the passenger seating capacity and other factors, the 
certification basis has a TR with criteria for the specific type of 
passenger emergency exit that is part of the design of the Model AW609. 
Another example involves fatigue evaluation. Part 25 contains 
requirements such as a limit of validity (LOV) on airframe fatigue for 
pressurized fuselages, which are not in part 29. Instead, fatigue 
evaluation in part 29 includes a composite structures fatigue rule, due 
to the more extreme fatigue environment of rotorcraft. For small 
airplanes, part 23, amendment

[[Page 86714]]

23-48, added a composite airframe evaluation requirement for bonded 
joints, which is included in agency compliance guidance for parts 25 
and 29 but not required by a specific regulation (the safety 
requirement is complied with through other broad existing regulations 
in those parts). Since the Model AW609 has a pressurized fuselage, the 
FAA developed TR criteria to include the LOV requirement. The 
certification basis incorporates by reference the part 29 composite 
rotorcraft structures fatigue rule, TR criteria to include the 
composite bonding requirements from part 23, as well as TR criteria to 
include fatigue requirements for elastomeric primary structural 
elements. The new requirements specific to the AWPC Model AW609 in the 
proposed airworthiness criteria used a ``TR.xxxx'' section-numbering 
scheme.

Summary of Changes From the Proposed Airworthiness Criteria

    Based on comments received, these final airworthiness criteria 
reflect the following changes, in addition to others as explained in 
more detail in the Discussion of Comments section:
     Added Sec.  29.1547 to the final airworthiness criteria 
for the case where a magnetic compass is installed.
     Revised these final airworthiness criteria to provide 
clarification on future certification for FIKI conditions.
     Clarified statements about TR.45 applicability.
     Revised proposed TR.575 to account for the unique nature 
and operating environment of elastomeric principle structural elements 
(PSEs).
     Updated Sec.  25.775 to clarify that the reference to 
Sec.  25.335(a) is replaced with TR.335(a) for the purposes of these 
airworthiness criteria.
     Did not include Sec.  25.875 and updated TR.875 in these 
final airworthiness criteria to prevent confusion between the terms 
propeller and proprotor, thereby combining proposed TR.875 and Sec.  
25.875, which call out requirements for buffeting, proprotor 
(propeller), and other rotating components. Accordingly, TR.875 in 
these final airworthiness criteria addresses both proposed TR.875 and 
Sec.  25.875.
     Revised the incorporation by reference of Sec.  29.1521 to 
reflect that the reference to Sec.  29.1509(c) is replaced with 
TR.1509(c) since Sec.  29.1509 is not part of the type certification 
basis for the Model AW609.
     Specified the amendment level for Sec.  25.1517 to be 25-
86.
     Revised these airworthiness criteria to remove Sec.  
25.1353 and include Sec.  29.1353 at amendment 29-59 for electrical 
wiring protection due to recent amendments to part 29.

Addition of Position Light TRs

    After the FAA issued the notice of proposed airworthiness criteria 
for public comment, AWPC presented a forward left and right position 
light design that would not meet the prescriptive regulatory 
requirements defined under Sec. Sec.  29.1385-29.1395. In general 
terms, the existing requirements define the use of a single left and a 
single right forward-looking position light. Due to the AW609 
configuration, AWPC proposed using multiple light sources for each 
forward position light providing lighting at a level comparable to the 
part 29 lighting requirements. The FAA developed TR.1385, TR.1387, 
TR.1389, TR.1391, TR.1393, and TR.1395 to establish the same level of 
safety to Sec. Sec.  29.1385, 29.1387, 29.1389, 29.1391, 29.1393, and 
Sec.  29.1395 to address the non-traditional configuration of the AW609 
powered-lift's position lights. These TRs modified the language in 
certain part 29 sections to allow for a group of forward position 
lights to be installed on each side of the aircraft.

Discussion of Comments

    The FAA received responses from six commenters including: Overair, 
Inc (Overair), Parker Lord Corporation (Parker Lord), Advanced Air 
Mobility Institute, Transport Canada, and two individual commenters.

Subpart A--General

    The FAA proposed criteria that adopted existing and developed 
definitions and abbreviations specifically for the Model AW609 powered-
lift under subpart A. The FAA received and reviewed comments from 
Transport Canada and Overair regarding subpart A of the proposed 
airworthiness criteria.
    Transport Canada requested the FAA revise TR.10(c) to use the 
phrase ``flightdeck'' instead of ``cockpit'' for consistency with 
TR.1322. The FAA concurs and has revised TR.10(c) to use the term 
``flightdeck.''
    Transport Canada requested the FAA revise TR.11 by adding a 
statement that abbreviations in these criteria apply in addition to the 
abbreviations in 14 CFR 1.2. The FAA does not agree with Transport 
Canada's request because 14 CFR part 1.2 abbreviations are applicable 
unless specifically addressed as not being applicable in the 
certification basis.
    Overair stated that ``VMIN'' as defined in TR.11(c) and 
``minimum safe speed'' as defined in other previously issued powered-
lift special class airworthiness criteria would cause confusion between 
the two terms. The FAA disagrees with Overair. The airworthiness 
criteria for the AW609 are a special class certification basis and as 
such, the requirements are specific for this aircraft rather than 
generally applicable. In addition, the development of the AW609 
certification basis predates the use of performance-based rules, which 
is the approach generally used for other special class powered-lift or 
similar aircraft.

Subpart B--Flight

    The FAA proposed criteria that adopted existing regulations from 
subpart B of parts 23, 25, and 29, as well as developed criteria 
specifically for the Model AW609 powered-lift . Subpart B covers a wide 
range of flight criteria including performance, controllability, trim, 
stability, and stalls.
    The FAA received and reviewed comments from Overair regarding 
subpart B of the proposed airworthiness criteria.
    Overair requested the FAA clarify the safety intent of TR.45 
related to the hovering ceiling given the differences in airworthiness 
criteria proposed for different powered-lift types. The FAA 
acknowledges Overair's request. TR.45 is general performance for 
Category A aircraft. The FAA developed these airworthiness criteria for 
the AW609 for guaranteed performance that would integrate all aircraft 
flight modes defined in TR.10 and HTR.45 including hover. TR Appendix 
H--Category B Performance defines Category B performance and HTR.45 
addresses general performance determination.
    Overair requested the FAA justify the climb performance identified 
in TR.67. Specifically, Overair requested the FAA explain why Sec.  
29.67(a)(1) was not adopted for the first takeoff segment and explain 
the rationale for adopting part 25 fixed-wing OEI minimum climb 
gradient criteria for this powered-lift special class aircraft. 
Finally, Overair inquired whether these performance requirements will 
provide the same level of safety when operating out of heliports and/or 
vertiports.
    The FAA acknowledges Overair's comment. The FAA determined Sec.  
29.67(a)(1), which establishes climb performance at 200 ft, was 
inappropriate for a transport category powered-lift such as the AW609. 
In addition, the FAA did not adopt part 25 fixed-wing OEI climb 
requirements for the AW609. Rather, the FAA established different 
takeoff flight paths for ground-level heliports under TR.59 and 
elevated heliports under TR.60 that do not exist

[[Page 86715]]

under part 25. The takeoff flight path under TR.59 and TR.69 utilizes 
the performance established under TR.67 to ensure positive engine out 
climb performance from the surface to 1500 ft above ground level, for 
different segments.
    Overair requested the FAA clarify why a stall speed has been 
adopted for the AW609 as opposed to the ``minimum safe speed'' in other 
powered-lift special class airworthiness criteria. The FAA acknowledges 
Overair's comment. The AW609 is a Sec.  21.17(b) special class 
certification basis aircraft and the airworthiness criteria are 
specific to this aircraft. Unlike other Sec.  21.17(b) powered-lift, 
the AW609 certification basis did not use performance-based criteria. 
There are differences between performance-based and prescriptive 
criteria. Conversion-mode minimum safe speed is covered elsewhere in 
the AW609 airworthiness criteria; in the AW609 airworthiness criteria, 
airplane-mode (wing-borne) minimum safe speed is covered in TR.103, 
201, 203, and 207. Conversion-mode (Semi-thrust borne) minimum safe 
speed is covered in TR.38 and 143. While the airworthiness criteria for 
the AW609 may be different from the airworthiness criteria for other 
powered-lift, the safety intent is the same with regards to stall and 
minimum speeds.
    Overair requested the FAA explain why the wind velocity 
requirement, from all azimuths, has been increased from ``at least 17 
knots'' in Sec.  29.143(c) to 20 knots. The FAA acknowledges Overair's 
comment. The AW609, as a special class aircraft, is a transport 
category aircraft and its certification basis includes appropriate 
requirements from both parts 25 and 29. Section 25.237(a)(1) requires 
``a 90-degree cross component of wind velocity, demonstrated to be safe 
for takeoff and landing, . . . [that] must be at least 20 knots . . .'' 
The FAA determined that Sec.  29.143(c) and (d)'s requirements of at 
least 17 knots all azimuth capability could provide a controllability 
gap for the AW609 when attempting to land or takeoff; as such the FAA 
adopted 20 knots to maintain consistency with transport aircraft 
requirements for specific applicability to the AW609. This approach is 
consistent with the draft ``Interim Airworthiness Criteria for Powered-
Lift Transport Category Aircraft,'' dated July 1988.
    The FAA received several comments from Overair on the topics of 
flight performance and characteristics, and Overair requested an 
explanation as to why the FAA adopted older, non-performance-based 
criteria. The FAA establishes the minimum safety standards without 
dictating designs. Manufacturers are free to choose the design strategy 
that suits their powered-lift, as long as these designs meet a minimum 
accepted safety standard.
    The FAA received multiple comments from Overair regarding the 
stability criteria proposed in TR.173 (static longitudinal stability), 
TR.175 (demonstration of static longitudinal stability), and TR.177 
(static lateral-directional stability). Overair asked for clarification 
as to why proposed TR.173, TR.175, and TR.177 include stability 
requirements from the 1960's instead of using recent special conditions 
for part 25 aircraft equipped with a full-authority electronic flight 
control system. Overair requested the FAA incorporate more current 
airworthiness standards for fly-by-wire technology into the AW609 
certification basis. The FAA does not concur with Overair's request to 
revise TR.173, TR.175, and TR.177 to incorporate recent special 
conditions for fly-by-wire technology. The recent fly-by-wire special 
conditions were considered in TR.173, TR.175, and TR.177. The 
commenter's assumption, that the recent special conditions were not 
considered for the TRs, is incorrect.
    Overair also inquired as to why proposed TR.181(a)(1) and 
TR.181(a)(2) (free and fixed position dynamic stability criteria, 
respectively) were included in the airworthiness criteria for an 
aircraft equipped with an irreversible electronic flight control 
system. Overair requested the FAA not adopt proposed TR.181(a)(1) and 
TR.181(a)(2) in the final airworthiness criteria. The FAA does not 
concur with Overair's request to not adopt proposed TR.181(a)(1) and 
TR.181(a)(2) in the final airworthiness criteria. The FAA determined 
that evaluation of free and fixed flight control characteristics is 
necessary even if an aircraft has an irreversible electronic flight 
control system.

Subpart C--Structure and Strength

    The FAA proposed criteria that adopted existing regulations from 
subpart C of parts 25 and 29, as well as developed criteria 
specifically for the AW609. Subpart C covers a wide range of strength 
criteria including flight loads, control surface loads, emergency 
landing conditions, and fatigue evaluations. The FAA received and 
reviewed comments from Parker Lord and one individual commenter.
    Parker Lord requested the FAA revise the definition of a Primary 
Structural Element (PSE). Parker Lord also recommended the FAA change 
the qualification and certification of elastomeric PSEs from physical 
and static strength attributes to material functionality and the 
dynamic response within the design requirements of the rotor system. 
The FAA agrees with Parker Lord's requests and has revised the language 
in final TR.575 to use the designed dynamic response of the material as 
compliance criteria instead of traditional static loading, deformation, 
and fatigue for compliance criteria.
    An individual commenter suggested the AW609 may become unstable in 
a windmilling condition and may develop whirl flutter. The commenter 
stated the aircraft should be tested for stability in this situation 
and if necessary given procedures and limitations. The commenter also 
stated that if the system design prevents windmilling, there should be 
backup systems and procedures. FAA acknowledges the commenter's 
concern. Windmilling impact on aircraft stability, including any impact 
on whirl flutter, is already evaluated under Sec.  25.629 and TR.629, 
therefore, no additional changes are deemed necessary to those 
airworthiness criteria.

Subpart D--Design and Construction

    The FAA proposed criteria that adopted existing regulations from 
subpart D of parts 25 and 29, as well as developed criteria 
specifically for the Model AW609 powered-lift. Subpart D covers a wide 
range of design and construction criteria including criteria covering 
rotors, control systems, landing gear, and personnel and cargo 
accommodations.
    The FAA received and reviewed comments from Overair and Transport 
Canada regarding subpart D of the proposed airworthiness criteria.
    Transport Canada requested the FAA specify which paragraphs of 
Sec.  25.335 and TR.335 the FAA is referring to in the reference to 
Sec.  25.775 in the proposed airworthiness criteria. The FAA has 
revised the reference to Sec.  25.775 in the final airworthiness 
criteria to indicate that Sec.  25.335(a) is replaced with TR.335(a).
    Transport Canada requested the FAA add Sec.  25.865 to the final 
airworthiness criteria because that regulation addresses fire 
protection requirements for the engine mounting structure and engine 
attachment points. The FAA does not agree with Transport Canada's 
request. Section 29.861(a) is included in the final airworthiness 
criteria, and uses the term ``structure,'' which includes engine mounts 
as indicated by the example in the guidance material of AC 29.861. As a 
result, compliance with Sec.  29.861(a) must also address engine

[[Page 86716]]

mounting structure and engine attachment points. Applying Sec.  
29.861(a) is sufficient for this powered-lift, and requiring compliance 
to Sec.  25.865 is not necessary. AC 29-2C ``Certification of Transport 
Category Rotorcraft'' and AC 29.861 ``Fire Protection of Structure, 
Controls, and Other Parts'' provide guidance for engine mounts and fire 
protection requirements.
    Transport Canada stated that Sec.  25.867 does not define clearly 
what surfaces to consider as ``rear of the nacelles'' and requested the 
FAA clarify the intent with a figure to define the envelope and 
boundaries radially and axially. The FAA does not agree with Transport 
Canada's request to provide a figure as this figure is defined in the 
project specific methods of compliance to Sec.  25.867.
    Transport Canada requested a rationalization of the FAA's exception 
of Sec.  25.869(a)(3) from the proposed airworthiness criteria and 
requested the FAA include Sec.  25.869(a)(3) in the final airworthiness 
criteria. Additionally, the commenter provided wording for Sec.  
25.869(a)(3) from amendment 25-113 even though the current amendment is 
25-123, which has different language. The FAA does not concur with 
Transport Canada's request to include Sec.  25.869(a)(3) at either 
amendment level in the final airworthiness criteria as the 
airworthiness criteria already contain criteria such as Sec.  29.1301, 
TR.1309, and Sec.  29.1353 that are intended to address the same 
requirements as those covered by the various part 25 wiring and EWIS 
requirements, including Sec.  25.869(a)(3).
    Overair commented that the inclusion of both Sec.  25.675(a) and 
Sec.  29.675(a) in the proposed airworthiness criteria was confusing 
and requested the FAA not make Sec.  25.675(a) applicable to the AW609 
because Sec.  29.675(a) is also applicable. The FAA does not concur 
with this request. Both regulations need to be included in the final 
airworthiness criteria because the AW609 operates in both helicopter 
and airplane modes including the conversion mode. The AW609 aircraft 
control is affected by rotor collective and cyclic pitch, conventional 
airplane control surfaces (elevator, flaperons), and nacelle tilt; 
traditional helicopter-type pilot controls in the cockpit provide 
aircraft control in pitch, roll, and yaw axes.
    Overair requested the FAA not adopt Sec.  25.875 from the proposed 
airworthiness criteria and reword TR.875 to prevent confusion. The FAA 
concurs with this request and has revised the final airworthiness 
criteria to not adopt Sec.  25.875 and reworded TR.875 to reflect the 
use of ``proprotors'' instead and of propellers to reflect TR.10(o) 
terminology.

Subpart E--Powerplant

    The FAA proposed criteria that adopted existing regulations from 
subpart E of parts 25 and 29, as well as developed criteria 
specifically for the Model AW609 powered-lift. Subpart E covers a wide 
range of powerplant criteria including rotor drive systems, fuel 
systems, oil systems, and cooling and exhaust systems. The FAA received 
and reviewed comments from Transport Canada and one individual 
commenter regarding subpart E of the proposed airworthiness criteria.
    Transport Canada requested the FAA revise proposed TR.963 to remove 
the phrase ``for compliance with'' and replace it with ``in addition 
to.'' FAA does not concur with Transport Canada's request. The 
requested change would increase the testing requirements for flexible 
fuel tank bladders in a way that is not intended.
    Transport Canada requested the FAA rationalize the exception of 
Sec.  25.1203(h) from the proposed airworthiness criteria and to 
include Sec.  25.1203(h) in the final airworthiness criteria. The FAA 
does not concur with the request to include Sec.  25.1203(h) in the 
final airworthiness criteria as the airworthiness criteria already 
contain criteria such as Sec.  29.1301, TR.1309, and Sec.  29.1353 that 
are intended to address similar requirements as those covered by the 
various part 25 EWIS requirements, including Sec.  25.1203(h).
    The FAA received several comments with no specific requested 
changes to the proposed airworthiness criteria from an individual on 
several aspects regarding FIKI, icing protection, and inadvertent icing 
encounters.
    The commenter inquired as to whether the AW609 has any relief from 
the subpart E powerplant-related requirements of normal FIKI 
certification other than having no subpart B testing with ice shapes 
and the relief of limited exposure time. The commenter also inquired as 
to whether the flight manual limitation that ``the pilot is prohibited 
from flight into known or forecast icing'' reduces or eliminates any of 
the other subpart E requirements for the AW609 that are normally 
included in a FIKI certification. The FAA acknowledges the commenter's 
questions: the powerplant icing requirements are applicable per 
TR.1093, regardless of the aircraft's FIKI status.

Subpart G--Operating Limitations and Information

    The FAA proposed criteria that adopted existing regulations from 
subpart G of parts 25 and 29, as well as developed criteria 
specifically for the Model AW609 powered-lift. Subpart G covers a wide 
range of operating limitations and information criteria including 
airspeed, markings and placards, indicators, and flight manuals. The 
FAA received and reviewed comments from Transport Canada regarding 
subpart G of the proposed airworthiness criteria.
    Transport Canada requested the FAA revise the reference to Sec.  
25.1585(a)(8) in Sec.  25.1517 to read ``Sec.  25.1585(a)(3)'' and 
explained that Sec.  25.1585(a)(8) does not exist.'' The FAA 
acknowledges Transport Canada's request; however, the reference to 
Sec.  25.1585(a)(8) is correct. The FAA revised the final airworthiness 
criteria to indicate that the criteria includes Sec.  25.1517, Rough 
air speed, VRA is at amendment 25-86, which contains (a)(8).
    Transport Canada requested the FAA revise the reference to Sec.  
29.1509 and TR.1509 in Sec.  29.1521 to include the appropriate 
paragraphs. The FAA concurs and revised the reference to Sec.  29.1509 
and TR.1509 to indicate that paragraph (c) is the appropriate 
paragraph.
    Transport Canada requested the FAA add ``Sec.  29.1547 Magnetic 
direction indicator. (a)-(d) [Applicable to AW609]'' to the 
airworthiness criteria and, if the FAA agrees, then also add a 
reference to Sec.  29.1547 in TR.1501(b). The FAA concurs with adding 
Sec.  29.1547 to these final airworthiness criteria and notes that 
Sec.  29.1327 is the requirement for a magnetic compass and Sec.  
29.1547 is the requirement for a calibration card if a compass is 
installed. In lieu of a magnetic compass, Sec.  25.1303 and TR.1303 
allow for direction indicators (gyroscopically stabilized, magnetic or 
non-magnetic).

General Comments

    The FAA received comments on the proposed criteria that were not 
specific to any subpart from The Advanced Air Mobility Institute, 
Transport Canada, and one individual commenter.
    Transport Canada made several comments concerning the structure and 
formatting of the airworthiness criteria document. Transport Canada 
further stated that the airworthiness criteria as written references 
many requirements instead of writing the actual text for the 
airworthiness criteria. Transport Canada suggested the FAA write the 
actual text for airworthiness criteria throughout the

[[Page 86717]]

document to make explicit the text agreed to when these airworthiness 
criteria are finalized. The FAA disagrees, because the 14 CFR 
regulations listed in the airworthiness criteria for the AW609 are 
incorporated into the criteria by referencing the existing rule.
    Transport Canada stated that the formula in proposed TR.725 Limit 
drop test, paragraph (d), is incomplete. The FAA disagrees with 
Transport Canada. The formula is correctly stated in the proposed 
criteria, and matches the formula suggested by the commenter.
    Transport Canada stated the heading for proposed TR.103 Stall SPEED 
is incorrect and that the term ``SPEED'' should be lower case and in 
bold text. The FAA agrees with Transport Canada and has corrected the 
heading in TR.103 in the final airworthiness criteria.
    Transport Canada requested the FAA explain why Sec. Sec.  25.1701-
25.1733 for an EWIS were not included in the proposed airworthiness 
criteria and requested the FAA add Sec. Sec.  25.1701-25.1733. The FAA 
does not concur with Transport Canada's request to include Sec. Sec.  
25.170-25.1753 in the final airworthiness criteria as the FAA updated 
the final airworthiness criteria to replace Sec.  25.1353 with Sec.  
29.1353 due to the recent addition of amendment 29-59 which introduced 
a part 29 safety target for electrical wiring. The final airworthiness 
criteria also contain Sec.  29.1301, and TR.1309 which, in addition to 
Sec.  29.1353, address similar requirements to those covered by the 
referenced part 25 EWIS and energy storage requirements.
    Transport Canada requested the FAA clarify whether part 34, Fuel 
Venting and Exhaust Emission Requirements For Turbine Engine Powered 
Airplanes, is applicable to the AW609, either to the engine or 
aircraft, as fuel venting can be influenced by the engine's 
installation effects. The FAA acknowledges Transport Canada's concern. 
The AW609 uses the PT6C-67A, which is a turboshaft engine. Part 34 does 
not apply to turboshaft engines. As long as the AW609 continues to use 
a turboshaft engine, part 34 will not be applicable.
    Transport Canada requested the FAA clarify whether part 38, 
Airplane Fuel Efficiency Certification is applicable to the AW609. The 
AW609 certification basis precedes the promulgation of 14 CFR part 38, 
and thus part 38 is not applicable to the AW609.
    The Advanced Air Mobility Institute recommended the FAA update and 
expand the airworthiness criteria for the Model AW609 powered-lift to 
require the implementation of a mandatory safety management system 
(SMS), designated as TR criteria. The FAA does acknowledge the value of 
implementation of a proactive SMS system. However, implementation of 
SMS is beyond the scope of this present effort to designate the 
applicable airworthiness criteria for this powered-lift.

Applicability

    These airworthiness criteria, established under the provisions of 
Sec.  21.17(b), are applicable to the AWPC Model AW609 powered-lift. 
Should AWPC apply at a later date for a change to the type certificate 
to include another model, these airworthiness criteria would apply to 
that model as well, provided the FAA finds them appropriate in 
accordance with the requirements of subpart D to part 21.

Conclusion

    This action affects only certain airworthiness criteria for the 
AWPC Model AW609 powered-lift. It is not a standard of general 
applicability.

Authority Citation

    The authority citation for these airworthiness criteria is as 
follows:

    Authority: 49 U.S.C. 106(g), 40113, and 44701-44702, 44704.

Airworthiness Criteria

    Pursuant to the authority delegated to me by the Administrator, the 
following airworthiness criteria are issued as part of the type 
certification basis for the AgustaWestland Philadelphia Corporation 
Model AW609 powered-lift. You may view the final airworthiness criteria 
on the internet at www.regulations.gov in Docket No. FAA-2022-1726.

    Issued in Kansas City, Missouri, on October 25, 2024.
Patrick R. Mullen,
Manager, Technical Policy Branch, Policy and Standards Division, 
Aircraft Certification Service.
[FR Doc. 2024-25238 Filed 10-30-24; 8:45 am]
BILLING CODE 4910-13-P

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.