DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0675; Product Identifier 2019-NM-068-AD; Amendment
39-19815; AD 2019-24-12]
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 a report that certain fuselages
were delivered with nonconforming keel tension fittings and stringer
end fittings. This AD requires a detailed visual inspection of stringer
end fittings and keel fittings for loose or working fasteners, signs of
wear, and corrosion, and repair if necessary; and a general visual
inspection of the keel tension fitting and stringer end fittings, as
applicable, and repairs and replacement of the keel and stringer end
fittings if necessary. The FAA is issuing this AD to address the unsafe
condition on these products.

DATES: This AD is effective February 3, 2020.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of February 3,
2020.

ADDRESSES: For Bombardier, Inc., or De Havilland Aircraft of Canada
Limited 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; phone: 416-375-
4000; fax: 416-375-4539; email: thd@dehavilland.com; internet: https://
dehavilland.com. You may view this service information at the FAA,
Transport Standards 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-2019-0675.

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-2019-
0675; 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 regulatory evaluation, 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: Andrea Jimenez, Aerospace Engineer,
Airframe and Propulsion Section, FAA, New York ACO Branch, 1600 Stewart
Avenue, Suite 410, Westbury, NY 11590; phone: 516-228-7330; fax: 516-
794-5531; email: 9-avs-nyaco-cos@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian AD CF-2019-06, dated February
18, 2019 (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-2019-0675.
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to certain Bombardier,
Inc., Model DHC-8-401 and -402 airplanes. The NPRM published in the
Federal Register on September 9, 2019 (84 FR 47170). The NPRM was
prompted by a report that certain fuselages were delivered with non-
conforming keel tension fittings and stringer end fittings. The NPRM
proposed to require a detailed visual inspection of stringer end
fittings and keel fittings for loose or working fasteners, signs of
wear, and corrosion, and repair if necessary; and a general visual
inspection of the keel tension fitting and stringer end fittings, as
applicable, and repairs and replacement of the keel and stringer end
fittings if necessary. The FAA is issuing this AD to address non-
conforming keel tension fittings and stringer end fittings, which could
lead to premature cracking and corrosion in several locations and
compromise the structural integrity of the fuselage joints. See the
MCAI for additional background information.

Comments

The FAA gave the public the opportunity to participate in
developing this final rule. The following presents the comments
received on the NPRM and the FAA's response to each comment.

Request To Update the Design Approval Holder (DAH) for the Affected
Airplanes

Horizon Air requested that the FAA update the DAH for the affected
airplanes. Horizon Air pointed out that De Havilland Aircraft of Canada
Limited is now the DAH for the Model DHC-8-401 and -402 airplanes.
The FAA agrees with the commenter for the reasons provided and has
updated this final rule accordingly.

Request To Include Revised Service Information and Credit for Previous
Revision

Horizon Air requested that the FAA update the final rule to include
revised service information. Horizon Air mentioned that De Havilland
Aircraft of Canada Limited has issued Service Bulletin 84-53-75,
Revision A, dated August 2, 2019. Horizon Air also requested that the
FAA give credit for accomplishment of the required actions prior to the
effective date of this AD using Bombardier Service Bulletin 84-53-75,
dated August 29, 2018.
The FAA agrees with the commenter for the reasons provided and has
updated this final rule to refer to De Havilland Aircraft of Canada
Limited Service Bulletin 84-53-75, Revision A, dated August 2, 2019.
The FAA has determined that no additional work is
required for airplanes on which the actions specified in Bombardier
Service Bulletin 84-53-75, dated August 29, 2018, have already been
done. The FAA has added paragraph (k) to this AD to provide credit for
accomplishment of the required actions prior to the effective date of
this AD using Bombardier Service Bulletin 84-53-75, dated August 29,
2018.

Conclusion

The FAA reviewed the relevant data, considered the comments
received, and determined that air safety and the public interest
require adopting this final rule with the changes described previously
and minor editorial changes. We have 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.
The FAA also determined that these changes will not increase the
economic burden on any operator or increase the scope of this final
rule.

Related Service Information Under 1 CFR Part 51

De Havilland Aircraft of Canada Limited has issued the following
service information.
Bombardier Service Bulletin 84-53-74, dated August 29,
2018. This service information describes procedures for a general
visual inspection of the keel and stringer end fittings, repair, and
replacement of the keel and stringer end fittings.
Service Bulletin 84-53-75, Revision A, dated August 2,
2019. This service information describes procedures for a detailed
visual inspection of stringer end fittings and keel fittings, in the
passenger compartment at stations X373.15 and X428.50, for loose or
working fasteners, signs of wear, and corrosion.
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 1 airplane of U.S. registry.
The FAA estimates the following costs to comply with this AD:

Estimated Costs for Required Actions

The FAA has received no definitive data that would enable the
agency to provide cost estimates for the on-condition replacements
specified in this AD.

Estimated Costs of On-Condition Replacements

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.
This AD is issued in accordance with authority delegated by the
Executive Director, Aircraft Certification Service, as authorized by
FAA Order 8000.51C. In accordance with that order, issuance of ADs is
normally a function of the Compliance and Airworthiness Division, but
during this transition period, the Executive Director has delegated the
authority to issue ADs applicable to transport category airplanes and
associated appliances to the Director of the System Oversight Division.

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 (AD):