DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-0756; Project Identifier MCAI-2023-00549-T]
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: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede Airworthiness Directive (AD)
2021-25-12 and AD 2022-11-11, which apply to certain De Havilland
Aircraft of Canada Limited Model DHC-8-401 and -402 airplanes. AD 2021-
25-12 requires repetitive lubrications of the trailing arm of the nose
landing gear (NLG). AD 2021-25-12 also requires revising the existing
maintenance or inspection program to include new and revised
airworthiness limitations. AD 2022-11-11 requires a modification to the
NLG shock strut assembly. Since the FAA issued AD 2021-25-12 and AD
2022-11-11, it has been determined that the pivot pin and tow fitting
assembly of the NLG must be replaced. This proposed AD would continue
to require the actions specified in AD 2021-25-12 and AD 2022-11-11 and
would 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. The FAA is proposing this AD to
address the unsafe condition on these products.

DATES: The FAA must receive comments on this proposed AD by May 6,
2024.

ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
Federal eRulemaking Portal: Go to regulations.gov. Follow
the instructions for submitting comments.
Fax: 202-493-2251.
Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE, Washington, DC 20590.
Hand Delivery: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
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 NPRM, the mandatory continuing airworthiness
information (MCAI), any comments received, and other information. The
street address for Docket Operations is listed above.
Material Incorporated by Reference:
For service information identified in this NPRM, 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 service information 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.

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:

Comments Invited

The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under ADDRESSES. Include ``Docket No. FAA-2024-0756; Project Identifier
MCAI-2023-00549-T'' at the beginning of your comments. The most helpful
comments reference a specific portion of the proposal, explain the
reason for any recommended change, and include supporting data. The FAA
will consider all comments received by the closing date and may amend
the proposal because of those comments.
Except for Confidential Business Information (CBI) as described in
the following paragraph, and other information as described in 14 CFR
11.35, the FAA will post all comments received, without change, to
regulations.gov, including any personal information you provide. The
agency will also post a report summarizing each substantive verbal
contact received about this NPRM.

Confidential Business Information

CBI is commercial or financial information that is both customarily
and actually treated as private by its owner. Under the Freedom of
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public disclosure.
If your comments responsive to this NPRM contain commercial or financial
information that is customarily treated as private, that you actually
treat as private, and that is relevant or responsive to this NPRM, it
is important that you clearly designate the submitted comments as CBI.
Please mark each page of your submission containing CBI as ``PROPIN.''
The FAA will treat such marked submissions as confidential under the
FOIA, and they will not be placed in the public docket of this NPRM.
Submissions containing CBI should be sent to Deep Gaurav, Aviation
Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY
11590; telephone 518-228-7300; email 9-avs-nyaco-cos@faa.gov. Any
commentary that the FAA receives which is not specifically designated
as CBI will be placed in the public docket for this rulemaking.

Background

The FAA issued 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), for certain
DeHavilland Aircraft of Canada Limited Model DHC-8-401 and -402
airplanes. AD 2021-25-12 and AD 2022-11-11 were prompted by an MCAI
originated by Transport Canada, which is the aviation authority for
Canada. Transport Canada issued AD CF-2009-29R4, dated October 1, 2021
(Transport Canada AD CF-2009-29R4), to correct an unsafe condition.
AD 2021-25-12 requires repetitive lubrications of the trailing arm
of the NLG. AD 2021-25-12 also requires revising the existing
maintenance or inspection program to include new and revised
airworthiness limitations (life limits for certain bolts). AD 2022-11-
11 requires 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.

Actions Since AD 2021-25-12 and AD 2022-11-11 Were Issued

Since the FAA issued AD 2021-25-12 and AD 2022-11-11, Transport
Canada superseded AD CF-2009-29R4, and issued Transport Canada AD CF-
2023-22, dated March 30, 2023 (Transport Canada AD CF-2023-22)
(referred to after this as the MCAI), to correct an unsafe condition on
certain DeHavilland Aircraft of Canada Limited Model DHC-8-401 and -402
airplanes. 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 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. This proposed AD would also remove
airplanes from the applicability of AD 2021-25-12 and AD 2022-11-11.
The FAA is proposing 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.

Related Service Information 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
service information 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 proposed AD would also require 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 proposed AD would also require 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 service information 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.

FAA's Determination

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
and service information referenced above. The FAA is issuing this NPRM
after determining that unsafe condition described previously is likely
to exist or develop on other products of the same type design.

Proposed AD Requirements in This NPRM

This proposed AD would continue to require the actions specified in
AD 2021-25-12 and AD 2022-11-11 and would also require accomplishing
the actions specified in the service information described previously.
This proposed AD would also prohibit the installation of affected
parts.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 41 airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed
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 has determined that this proposed AD would not have
federalism implications under Executive Order 13132. This proposed AD
would 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 this proposed
regulation:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Would not affect intrastate aviation in Alaska, and
(3) Would 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 Proposed Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 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: