DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-0756; Project Identifier MCAI-2023-00549-T;
Amendment 39-22769; AD 2024-12-05]
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 superseding Airworthiness Directive (AD) 2021-25-12
and AD 2022-11-11, which applied to certain De Havilland Aircraft of
Canada Limited Model DHC-8-401 and -402 airplanes. AD 2021-25-12
required repetitive lubrications of the trailing arm of the nose
landing gear (NLG). AD 2021-25-12 also required revising the existing
maintenance or inspection program to include new and revised
airworthiness limitations. AD 2022-11-11 required a modification to the
NLG shock strut assembly. This AD continues to require the actions
specified in AD 2021-25-12 and AD 2022-11-11 and requires replacement
of the pivot pin and tow fitting assembly with a new, improved pivot
pin and tow fitting assembly and prohibits the installation of affected
parts. This AD was prompted by a determination that the pivot pin and
tow fitting assembly of the NLG must be replaced. The FAA is issuing
this AD to address the unsafe condition on these products.

DATES: This AD is effective August 21, 2024.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of August 21,
2024.
The Director of the Federal Register approved the incorporation by
reference of a certain other publication listed in this AD as of July
8, 2022 (87 FR 33627, June 3, 2022).
The Director of the Federal Register approved the incorporation by
reference of certain other publications listed in this AD as of January
5, 2022 (86 FR 72174, December 21, 2021).

ADDRESSES:
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2024-0756; 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 De Havilland material identified in this AD, contact
De Havilland Aircraft of Canada Limited, Dash 8 Series Customer
Response Centre, 5800 Explorer Drive, Mississauga, Ontario, L4W 5K9,
Canada; telephone North America (toll-free): 855-310-1013, Direct: 647-
277-5820; email thd@dehavilland.com; website dehavilland.com.
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-2024-0756.

FOR FURTHER INFORMATION CONTACT: Deep Gaurav, 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 to supersede AD 2021-25-12, Amendment 39-21856 (86 FR
72174, December 21, 2021) (AD 2021-25-12); and AD 2022-11-11, Amendment
39-22061 (87 FR 33627, June 3, 2022) (AD 2022-11-11). AD 2021-25-12 and
AD 2022-11-11 applied to certain DeHavilland Aircraft of Canada Limited
Model DHC-8-401 and -402 airplanes. AD 2021-25-12 required repetitive
lubrications of the trailing arm of the NLG. AD 2021-25-12 also
required revising the existing maintenance or inspection program to
include new and revised airworthiness limitations (life limits for
certain bolts). AD 2022-11-11 required modification to the NLG shock
strut assembly. The FAA issued AD 2021-25-12 and AD 2022-11-11 to
address failure of the pivot pin retention bolt, which could result in
a loss of directional control or loss of an NLG tire during takeoff or
landing, which could lead to runway excursions.
The NPRM published in the Federal Register on March 22, 2024 (89 FR
20367). The NPRM was prompted by AD CF-2023-22, dated March 30, 2023
(Transport Canada AD CF-2023-22) (also referred to as the MCAI), issued
by Transport Canada, which is the aviation authority for Canada.
Transport Canada AD CF-2023-22 superseded Transport Canada AD CF-2009-
29R4, October 1, 2021 (Transport Canada AD CF-2009-29R4). The MCAI
states that it requires the removal of pivot pin part number (P/N)
47127-1 or P/N 47127-3 and tow fitting assembly P/N 47160-1, and their
replacement with pivot pin P/N 47127-5 and tow fitting assembly P/N
47160-3, as terminating action to the requirements of Transport Canada
AD CF-2009-29R4. The pivot pin P/N 47127-5 is now attached directly to
the new tow fitting lug and no longer requires the use of a retention
bolt. Transport Canada AD CF-2023-22 also prohibits the installation of
certain parts.
In the NPRM, the FAA proposed to continue to require the actions
specified in AD 2021-25-12 and AD 2022-11-11 and to require replacement
of the pivot pin and tow fitting assembly with a new, improved pivot
pin and tow fitting assembly and prohibit the installation of affected
parts. In the NPRM, the FAA also proposed to remove airplanes from the
applicability of AD 2021-25-12 and AD 2022-11-11. 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-2024-0756.

Discussion of Final Airworthiness Directive

Comments

The FAA received no comments on the NPRM or on the determination of
the cost to the public.

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 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, 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

The FAA reviewed De Havilland Aircraft of Canada Limited Service
Bulletin 84-32-173, dated November 15, 2022, including Collins
Aerospace Service Bulletin 47100-32-153, dated November 10, 2022. This
material specifies procedures for replacing the pivot pin retention
mechanism and tow fitting assembly with a new, improved pivot pin and
tow fitting assembly, which consists of removing pivot pin linkage
components and replacing pivot pin P/N 47127-1 or P/N 47127-3 and tow
fitting assembly P/N 47160-1 with pivot pin P/N 47127-5 and tow fitting
assembly P/N 47160-3.
This AD also requires De Havilland Aircraft of Canada Limited
Service Bulletin 84-32-161, Revision B, dated March 31, 2021, including
UTC Aerospace Systems Service Bulletin 47100-32-145, Revision 3, dated
March 26, 2021, which the Director of the Federal Register approved for
incorporation by reference as of July 8, 2022 (87 FR 33627, June 3,
2022).
This AD also requires De Havilland Aircraft of Canada Limited
Service Bulletin 84-32-167, dated August 12, 2021; and De Havilland
Aircraft of Canada Limited Temporary Revision ALI-0223, dated October
15, 2020, which the Director of the Federal Register approved for
incorporation by reference as of January 5, 2022 (86 FR 72174, December
21, 2021).
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 the ADDRESSES section.

Costs of Compliance

The FAA estimates that this AD will affect 41 airplanes of U.S.
registry.
The FAA estimates the following costs to comply with this AD:

Estimated Costs for Required Actions

* Table does not include estimated costs for revising the maintenance or
inspection program.

The FAA has determined that revising the maintenance or inspection
program takes an average of 90 work-hours per operator, although the
FAA recognizes that this number may vary from operator to operator. In
the past, the FAA has
estimated that this action takes 1 work-hour per airplane. Since
operators incorporate maintenance or inspection program changes for
their affected fleet(s), the FAA has determined that a per-operator
estimate is more accurate than a per-airplane estimate. Therefore, the
FAA estimates the total cost per operator to be $7,650 (90 work-hours x
$85 per work-hour).
The FAA estimates the following costs to do any necessary on-
condition actions that would be required based on the results of any
required actions. The FAA has no way of determining the number of
aircraft that might need these on-condition actions:

Estimated Costs of On-Condition Actions

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

The FAA determined that 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.

Sec. 39.13 [Amended]

2. The FAA amends Sec. 39.13 by:

a. Removing Airworthiness Directive (AD) 2021-25-12, Amendment 39-21856
(86 FR 72174, December 21, 2021); and AD 2022-11-11, Amendment 39-22061
(87 FR 33627, June 3, 2022); and

b. Adding the following new AD: