DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-2420; Project Identifier MCAI-2024-00143-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)
2022-01-02, which applies to certain De Havilland Aircraft of Canada
Limited Model DHC-8-400, -401, and -402 airplanes. AD 2022-01-02
requires inspecting for corrosion of the nacelle to wing rear spar
attachment pins, and the nacelle to landing gear attachment pins, and
doing all applicable corrective actions. Since the FAA issued AD 2022-
01-02, it was discovered that some operators were unable to identify
the airplanes subject to each requirement. This proposed AD would
continue to require the actions specified in AD 2022-01-02, clarify the
affected airplanes for each required action, and revise the
applicability by removing Model DHC-8-400 airplanes, as specified in a
Transport Canada AD, which is proposed for incorporation by reference
(IBR). This proposed AD would also revise a certain compliance time.
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 December
27, 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-2024-2420; 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 Transport Canada material identified in this proposed
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; 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.

FOR FURTHER INFORMATION CONTACT: Fatin Saumik, 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 the ADDRESSES section. Include "Docket No. FAA-2024-2420;
Project Identifier MCAI-2024-00143-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 Fatin
Saumik, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410,
Westbury, NY 11590; telephone 516-228-7300; 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 2022-01-02, Amendment 39-21890 (87 FR 4145,
January 27, 2022) (AD 2022-01-02), for certain De Havilland Aircraft of
Canada Limited Model DHC-8-400, -401, and -402 airplanes. AD 2022-01-02
was prompted by MCAI originated by Transport Canada, which is the
aviation authority for Canada. Transport Canada issued AD CF-2020-51R1,
dated February 24, 2021 (Transport Canada AD CF-2020-51R1), to correct
an unsafe condition.

AD 2022-01-02 requires doing a detailed visual inspection of the
nacelle to wing rear spar attachment pins, and the nacelle to landing
gear attachment pins, for any corrosion, and doing all applicable
corrective actions. The FAA issued AD 2022-01-02 to address premature
corrosion and subsequent failure of the nacelle to landing gear and
nacelle to rear wing spar attachment pins, which, if undetected, could
lead to a single or dual collapse of the main landing gear.

Actions Since AD 2022-01-02 Was Issued

Since the FAA issued AD 2022-01-02, Transport Canada superseded AD
CF-2020-51R1, dated February 24, 2021. Transport Canada AD CF-2020-
51R2, dated February 27, 2024 (Transport Canada AD CF-2020-51R2)
(referred to after this as the MCAI), was issued to correct an unsafe
condition on certain De Havilland Aircraft of Canada Limited Model DHC-
8-401 and -402 airplanes.

The MCAI provides clarification of the applicability for each of
its parts (Parts I through V) and otherwise maintains the requirements
of AD CF-2020-51R1. It also revises the applicability section to remove
Model DHC-8-400 airplanes since no model DHC-8-400 airplanes have been
delivered.

In addition, the FAA discovered an error in AD 2022-01-02, which
included a compliance time that incorrectly used the number of flight
cycles on the airplane instead of on the pins.

The FAA is proposing this AD to address premature corrosion and
subsequent failure of the nacelle to landing gear and nacelle to rear
wing spar attachment pins, which, if undetected, could lead to a single
or dual collapse of the main landing gear.

You may examine the MCAI in the AD docket at regulations.gov under
Docket No. FAA-2024-2420.

Explanation of Retained Requirements

Although this proposed AD does not explicitly restate the
requirements of AD 2022-01-02, this proposed AD would retain all of the
requirements of AD 2022-01-02. Those requirements are referenced in
Transport Canada AD CF-2020-51R2, which, in turn, is referenced in
paragraph (g) of this proposed AD.

Related Material Under 1 CFR Part 51

Transport Canada AD CF-2020-51R2 specifies procedures for doing a
detailed visual inspection of the nacelle to wing rear spar attachment
pins, and the nacelle to landing gear attachment pins, for any
corrosion; and doing all applicable corrective actions. Corrective
actions include applying epoxy primer to the bore surface of the pins,
performing a fluorescent magnetic particle inspection for any cracking,
removing corrosion, reworking and part marking certain pins, and
replacing any cracked or corroded pins with serviceable pins.

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.

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
material referenced above. The FAA is issuing this NPRM after
determining that the 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 retain all requirements of AD 2022-01-02 and
clarify the airplanes subject to each requirement. This proposed AD
would remove Model DHC-8-400 airplanes from the applicability and
revise a certain compliance time as specified in an exception in
paragraph (h)(2) of this proposed AD.

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

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 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) 2022-01-02, Amendment 39-21890
(87 FR 4145, January 27, 2022); and

b. Adding the following new AD: