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 Department of Transportation Federal Aviation Administration 14 CFR Part 39
[Docket No. FAA-2024-1692; Project Identifier MCAI-2024-00050-T; Amendment 39-22878; AD 2024-22-07]
RIN 2120-AA64
 AGENCY: Federal Aviation Administration (FAA), DOT.
 ACTION: Final rule.
 SUMMARY: The FAA is adopting a new airworthiness directive (AD) for certain De Havilland Aircraft of Canada Limited Model DHC-8-401 and -402 airplanes. This AD was prompted by a report of an in-flight event where isolation valve caution messages were received. This AD requires inspecting the fuse/shuttle valve serial numbers, and replacing certain fuse/shuttle valves, as specified in a Transport Canada AD, which is incorporated by reference (IBR). The FAA is issuing this AD to address the unsafe condition on these products.
 DATES: This AD is effective December 31, 2024. The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of December 31, 2024.
 ADDRESSES:  *AD Docket:*
                         You may examine the AD docket at regulations.gov under Docket No. FAA-2024-1692; 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, the mandatory continuing airworthiness information (MCAI), 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 Transport Canada material identified in this AD, contact Transport Canada, Transport Canada National Aircraft Certification, 159 Cleopatra Drive, Nepean, Ontario K1A 0N5, Canada; telephone 888-663-3639; email*TC.AirworthinessDirectives-Consignesdenavigabilite.TC@tc.gc.ca*. You may find this material on the Transport Canada website at 
                        *tc.canada.ca/en/aviation.*
                    You may view this material at the FAA, Airworthiness Products Section, Operational Safety Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 206-231-3195. It is also available at regulations.gov under Docket No. FAA-2024-1692.
 FOR FURTHER INFORMATION CONTACT: Gabriel Kim, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone: 516-228-7300; email: 
                        *9-avs-nyaco-cos@faa.gov.*


SUPPLEMENTARY INFORMATION: Background The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain De Havilland Aircraft of Canada Limited Model DHC-8-401 and -402 airplanes. The NPRM published in the 
                    **Federal Register**
                     on June 21, 2024 (89 FR 51988). The NPRM was prompted by AD CF-2024-01, dated January 11, 2024, issued by Transport Canada, which is the aviation authority for Canada (Transport Canada AD CF-2024-01) (also referred to as the MCAI). The MCAI states that an in-service event was reported where the crew received a number two isolation valve (ISO #2) caution message followed by a number one isolation valve (ISO #1) caution message. The landing gear was extended via an alternate extension system as the crew prepared for landing. Upon landing, the crew used the emergency brake to stop the airplane. The airplane stopped safely within the runway limits. Subsequent maintenance activity discovered an external leak from the main landing gear (MLG) brake assembly, and it was found that the fuse/shuttle valve assembly did not function properly. Further investigation revealed that the fuse/shuttle valve assembly failure resulted from a factory assembly error, which occurred on a limited number of fuse/shuttle valves. The assembly error can cause valve deformation leading to premature wear, and eventually fuse/shuttle valve failure. This condition, if not corrected, could result in the loss of powered landing gear extension/retraction, outboard and inboard spoilers, nose wheel steering, and normal braking, and possibly a runway excursion. In the NPRM, the FAA proposed to require inspecting the fuse/shuttle valve serial numbers, and replacing certain fuse/shuttle valves, as specified in Transport Canada AD CF-2024-01. The FAA is issuing this AD to address the unsafe condition on these products. You may examine the MCAI in the AD docket at 
                    *regulations.gov*
                     under Docket No. FAA-2024-1692. Discussion of Final Airworthiness Directive Comments The FAA received a comment from Air Line Pilots Association, International (ALPA). The following presents the comment received on the NPRM and the FAA's response to the comment. Request To Reduce Compliance Time ALPA stated the compliance time of 8,000 flight hours or 48 months whichever occurs first after the effective date of the proposed AD is excessive for such unsafe condition, that could result in the loss of powered landing gear extension/retraction, outboard and inboard spoilers, nose wheel steering, normal braking, and possibly a runway excursion. The FAA infers that ALPA is requesting the FAA reduce the compliance time. The FAA does not agree with the request. The FAA has determined that Transport Canada's compliance time calculation is adequate. The low probability of a critical event is due to the single occurrence and high flight hours. In addition, multiple isolation valves can effectively mitigate hydraulic fluid leaks. After considering all the available information, the FAA has determined that the compliance time, as proposed, represents an appropriate interval of time in which the required actions can be performed in a timely manner within the affected fleet, while still maintaining an adequate level of safety. Additionally, the FAA notes that there has been only one event of an in-service aircraft, and in that event, the aircraft landed safely. With only one event and the high amount of flight hours in the fleet, the probability of the 
                    ( print page 93163)
                    unsafe condition occurring is low. It is possible that all the systems listed in this AD could fail simultaneously; however, that is unlikely. Aircraft hydraulic systems typically have an isolation valve, which in this case was activated and annunciated. The isolation valve was effective, and although hydraulic fluid leaked, the hydraulic pressure remained at normal levels. This AD has not been changed regarding this request. Clarification of Unsafe Condition Paragraph (e) of the proposed AD states the FAA is issuing this AD to address certain fuse/shuttle valves. The FAA has revised paragraph (e) of this AD to state the FAA is issuing this AD to address failure of certain fuse/shuttle valves to clarify it is the failure of the fuse/shuttle valves that could lead to the unsafe condition. Conclusion This product has been approved by the aviation authority of another country and is approved for operation in the United States. Pursuant to the FAA's bilateral agreement with this State of Design Authority, it has notified the FAA of the unsafe condition described in the MCAI referenced above. The FAA reviewed the relevant data, considered the comment received, and determined that air safety requires adopting this AD as proposed. Accordingly, the FAA is issuing this AD to address the unsafe condition on this product. Except for minor editorial changes, and the change described previously, this AD is adopted as proposed in the NPRM. None of the changes will increase the economic burden on any operator. Material Incorporated by Reference Under 1 CFR Part 51 Transport Canada AD CF-2024-01 specifies procedures for inspecting the fuse/shuttle valve serial numbers, and if any fuse/shuttle valve assemblies with the listed serial numbers are found, replacing the affected fuse/shuttle valves. This material is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in 
                    **ADDRESSES**
                     section. Costs of Compliance The FAA estimates this AD affects 54 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD: Estimated Costs for Required Actions
Labor cost
Parts cost
Cost per 
                             product
Cost on U.S. operators1 work-hour × $85 per hour = $85
$0
$85
$4,590
 The FAA estimates the following costs to do any necessary on-condition action required based on the results of any required actions. The FAA has no way of determining the number of aircraft that might need this on-condition action: Estimated Costs of On-Condition Actions
Labor cost
Parts cost
Cost per 
                             product5 work-hours × $85 per hour = $425 per fuse/shuttle valve
$64,453 per fuse/shuttle valve assembly
$64,878
 The FAA included all known costs in its cost estimate. According to the manufacturer, however, some or all of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected operators. Authority for This Rulemaking Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency's authority. The FAA is issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701: General requirements. Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action. Regulatory Findings This AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. For the reasons discussed above, I certify that this AD: (1) Is not a “significant regulatory action” under Executive Order 12866, (2) Will not affect intrastate aviation in Alaska, and (3) Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. List of Subjects in 14 CFR Part 39 Air transportation
Aircraft
Aviation safety
Incorporation by reference
Safety
 The Amendment Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows: PART 39—AIRWORTHINESS DIRECTIVES
 1.The authority citation for part 39 continues to read as follows: Authority:
                        49 U.S.C. 106(g), 40113, 44701. § 39.13
 2.The FAA amends § 39.13 by adding the following new airworthiness directive: 
 
 **2024-22-07 De Havilland Aircraft of Canada Limited (Type Certificate Previously Held by Bombardier, Inc.):**
                             Amendment 39-22878; Docket No. FAA-2024-1692; Project Identifier MCAI-2024-00050-T. (a) Effective Date This airworthiness directive (AD) is effective December 31, 2024. (b) Affected ADs None. (c) Applicability This AD applies to De Havilland Aircraft of Canada Limited Model DHC-8-401 and -402 airplanes, certificated in any category, as identified in Transport Canada AD CF-2024-01, dated January 11, 2024 (Transport Canada AD CF-2024-01). (d) Subject Air Transport Association (ATA) of America Code 27, Flight Controls; 29, Hydraulic Power; and 32, Landing Gear. (e) Unsafe Condition This AD was prompted by a report of an in-flight event where isolation valve caution messages were received. The FAA is issuing this AD to address failure of certain fuse/shuttle valves. The unsafe condition, if not addressed, could result in the loss of powered landing gear extension/retraction, outboard and inboard spoilers, nose wheel steering, normal braking, and possibly a runway excursion. (f) Compliance Comply with this AD within the compliance times specified, unless already done. (g) Requirements Except as specified in paragraph (h) of this AD: Comply with all required actions and compliance times specified in, and in accordance with, Transport Canada AD CF-2024-01. (h) Exceptions to Transport Canada AD CF-2024-01 (1) Where Transport Canada AD CF-2024-01 refers to its effective date, this AD requires using the effective date of this AD. (2) Where Transport Canada AD CF-2024-01 refers to hours air time, this AD requires using flight hours. (i) Additional AD Provisions The following provisions also apply to this AD: (1) 
                            *Alternative Methods of Compliance (AMOCs):*
                             The Manager, International Validation Branch, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or responsible Flight Standards Office, as appropriate. If sending information directly to the manager of the International Validation Branch, mail it to the address identified in paragraph (j) of this AD. Information may be emailed to: 
                            *AMOC@faa.gov.*
                             Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the responsible Flight Standards Office. (2) 
                            *Contacting the Manufacturer:*
                             For any requirement in this AD to obtain instructions from a manufacturer, the instructions must be accomplished using a method approved by the Manager, International Validation Branch, FAA; or Transport Canada; or De Havilland Aircraft of Canada Limited's Transport Canada Design Approval Organization (DAO). If approved by the DAO, the approval must include the DAO-authorized signature. (j) Additional Information For more information about this AD, contact Gabriel Kim, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone: 516-228-7300; email: 
                            *9-avs-nyaco-cos@faa.gov.* (k) Material Incorporated by Reference (1) The Director of the Federal Register approved the incorporation by reference (IBR) of the service information listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51. (2) You must use this service information as applicable to do the actions required by this AD, unless this AD specifies otherwise. (i) Transport Canada AD CF-2024-01, dated January 11, 2024. (ii) [Reserved] (3) For Transport Canada AD CF-2024-01, contact Transport Canada, Transport Canada National Aircraft Certification, 159 Cleopatra Drive, Nepean, Ontario K1A 0N5, Canada; telephone 888-663-3639; email 
                            *TC.AirworthinessDirectives-Consignesdenavigabilite.TC@tc.gc.ca;*
                             website 
                            *tc.canada.ca/en/aviation.* (4) You may view this material at the FAA, Airworthiness Products Section, Operational Safety Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 206-231-3195. (5) You may view this material at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, visit 
                            *www.archives.gov/​federal-register/​cfr/​ibr-locations*
                             or email 
                            *fr.inspection@nara.gov.* Issued on October 28, 2024. Victor Wicklund, Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service.


[FR Doc. 2024-27593 Filed 11-25-24; 8:45 am] BILLING CODE 4910-13-P