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[Federal Register Volume 89, Number 228 (Tuesday, November 26, 2024)]
[Rules and Regulations]
[Pages 93162-93164]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-27593]

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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

Airworthiness Directives; De Havilland Aircraft of Canada Limited 
(Type Certificate Previously Held by Bombardier, Inc.) Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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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 [email protected]. 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: [email protected].

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

[[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
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                           Labor cost                               Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
1 work-hour x $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
------------------------------------------------------------------------
                                                             Cost per
            Labor cost                   Parts cost           product
------------------------------------------------------------------------
5 work-hours x $85 per hour = $425  $64,453 per fuse/            $64,878
 per fuse/shuttle valve.             shuttle valve
                                     assembly.
------------------------------------------------------------------------

    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

0
1. The authority citation for part 39 continues to read as follows:

    Authority:  49 U.S.C. 106(g), 40113, 44701.

Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive:

[[Page 93164]]

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: 
[email protected]. 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: [email protected].

(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 [email protected]; 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 [email protected].

    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
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