DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0656; Project Identifier MCAI-2021-00394-T;
Amendment 39-21800; AD 2021-23-02]
RIN 2120-AA64

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

AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (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 reports of loss of hydraulic
fluid and annunciation of the check fire detect light. This AD requires
doing a detailed visual inspection for chafing and proper clearance of
the left-hand (LH) and right-hand (RH) main landing gear (MLG) primary
zone advanced pneumatic detector (APD) sensing lines, the hydraulic
tube assemblies, and the surrounding structure, and doing all
applicable corrective action. The FAA is issuing this AD to address the
unsafe condition on these products.

DATES: This AD is effective January 5, 2022.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of January 5,
2022.

ADDRESSES: For service information identified in this final rule,
contact De Havilland Aircraft of Canada Limited, Q-Series Technical
Help Desk, 123 Garratt Boulevard, Toronto, Ontario M3K 1Y5, Canada;
telephone 416-375-4000; fax 416-375-4539; email thd@dehavilland.com;
internet https://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. It is also
available on the internet at https://www.regulations.gov by searching
for and locating Docket No. FAA-2021-0656.

Examining the AD Docket

You may examine the AD docket on the internet at https://www.regulations.
gov by searching for and locating Docket No. FAA-2021-
0656; 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, 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.

FOR FURTHER INFORMATION CONTACT: Chirayu Gupta, Aerospace Engineer,
Mechanical Systems and Administrative Services Section, FAA, New York
ACO Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
telephone 516-228-7300; fax 516-794-5531; email 9-avs-nyaco-cos@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued TCCA AD CF-2021-12, dated April 14,
2021 (also referred to as the Mandatory Continuing Airworthiness
Information, or the MCAI), to correct an unsafe condition for certain
De Havilland Aircraft of Canada Limited Model DHC-8-401 and -402
airplanes. You may examine the MCAI in the AD docket on the internet at
https://www.regulations.gov by searching for and locating Docket No.
FAA-2021-0656.
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 August 12, 2021 (86 FR 44324). The
NPRM was prompted by reports of loss of hydraulic fluid and
annunciation of the check fire detect light. The NPRM proposed to
require doing a detailed visual inspection for chafing and proper
clearance of the LH and RH MLG primary zone APD sensing lines, the
hydraulic tube assemblies, and the surrounding structure, and doing all
applicable corrective actions. The FAA is issuing this AD to address
insufficient separation between the APD sensing line and surrounding
components, which could lead to a hydraulic leak, loss of hydraulic
systems, and loss of fire detection in the MLG primary zone should
prolonged contact occur. See the MCAI for additional background
information.

Comments

The FAA gave the public the opportunity to participate in
developing this final rule. The FAA has considered the comment
received. The Air Line Pilots Association, International (ALPA) stated
that it supports the NPRM.

Conclusion

The FAA reviewed the relevant data, considered the comment
received, and determined that air safety and the public interest
require adopting this final rule as proposed, except for minor
editorial changes. The FAA has determined that these minor changes:
Are consistent with the intent that was proposed in the
NPRM for addressing the unsafe condition; and
Do not add any additional burden upon the public than was
already proposed in the NPRM.

Related Service Information Under 1 CFR Part 51

De Havilland Aircraft of Canada Limited has issued Service Bulletin
84-26-20, Revision A, dated March 9, 2021. This service information
describes procedures for doing a detailed visual inspection for chafing
and proper clearance of the LH and RH MLG primary zone APD sensing
lines, the hydraulic tube assemblies and the surrounding structure, and
doing all applicable corrective actions. Corrective actions include
repair and replacement of the APD sensing line and the hydraulic tube
assembly.
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.

Costs of Compliance

The FAA estimates that 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

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

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.

Adoption of 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 adding the following new airworthiness
directive: