DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0101; Product Identifier 2019-NM-190-AD]
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 adopt a new airworthiness directive (AD)
for certain De Havilland Aircraft of Canada Limited Model DHC-8-400
series airplanes. This proposed AD was prompted by a report that
certain elevator power control unit (PCU) arm fittings have
nonconforming fillet radii. This proposed AD would require an
inspection for affected elevator PCU assemblies, inspections of
affected elevator PCU arm fittings for nonconforming fillet radii and
cracks, replacement if necessary, and re-identification of the affected
elevator PCU assemblies. 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 April 9,
2020.

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 https://www.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.

For service information identified in this NPRM, 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.

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-2020-
0101; 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 regulatory evaluation, any comments received, and other
information. The street address for Docket Operations is listed above.
Comments will be available in the AD docket shortly after receipt.

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:

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-2020-0101;
Product Identifier 2019-NM-190-AD" at the beginning of your comments.
The FAA specifically invites comments on the overall regulatory,
economic, environmental, and energy aspects of this NPRM. The FAA will
consider all comments received by the closing date and may amend this
NPRM because of those comments.

The FAA will post all comments, without change, to https://www.regulations
.gov, including any personal information you provide.
The FAA will also post a report summarizing each substantive verbal
contact the agency receives about this NPRM.

Discussion

Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian AD CF-2019-36, dated October
18, 2019 ("AD CF-2019-36") (referred to after this as the Mandatory
Continuing Airworthiness Information, or "the MCAI"), to correct an
unsafe condition for certain De Havilland Aircraft of Canada Limited
Model DHC-8-400 series 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-2020-0101.

This proposed AD was prompted by a report that certain elevator PCU
arm fittings have nonconforming fillet radii. The FAA is proposing this
AD to address elevator PCU assemblies with nonconforming fillet radii,
which could lead to premature failure of the fitting and a jam in one
elevator; if the fittings on both elevators fail, a complete loss of
elevator control could occur. See the MCAI for additional background
information.

Related Service Information Under 1 CFR Part 51

De Havilland has issued Service Bulletin 84-55-10, Revision A,
dated July 25, 2019. This service information describes procedures for
an inspection for affected elevator PCU assemblies, inspections of
affected elevator PCU arm fittings for nonconforming fillet radii and
cracks, replacement if necessary, and re-identification of the affected
elevator PCU assemblies. 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 the State of Design Authority,
the FAA has been notified of the unsafe condition described in the MCAI
and service information referenced above. The FAA is proposing this AD
because the FAA evaluated all the relevant information and determined the
unsafe condition described previously is likely to exist or develop on
other products of the same type design.

Proposed Requirements of This NPRM

This proposed AD would require accomplishing the actions specified
in the service information described previously, except as discussed
under "Differences Between this Proposed AD and the MCAI or Service
Information."

Differences Between This Proposed AD and the MCAI or Service
Information

Canadian AD CF-2019-36 specifies to do the required inspections
before accumulating 8,000 flight cycles from the effective date of
Canadian AD CF-2019-36, or before accumulating 30,000 total flight
cycles, whichever occurs first. TCCA's risk assessment was developed
using flight cycles on the elevator PCU assembly (which was
inadvertently omitted from the Canadian AD). The FAA has determined
that using the compliance times specified in the Canadian AD could
inadvertently ground certain airplanes. Therefore, the FAA finds that
the inspection must be accomplished within 8,000 flight cycles on the
elevator PCU assembly after the effective date of this AD, or before
the accumulation of 30,000 total flight cycles on the elevator PCU
assembly, whichever occurs first, which represents an appropriate
interval of time for affected airplanes to continue to operate without
compromising safety.

Costs of Compliance

The FAA estimates that this proposed AD affects 38 airplanes of
U.S. registry. The FAA estimates the following costs to comply with
this proposed AD:

Estimated Costs for Required Actions

The FAA estimates the following costs to do any necessary on-
condition replacement that would be required based on the results of
any required inspections. The FAA has no way of determining the number
of aircraft that might need this on-condition replacement:

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 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) 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 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 adding the following new airworthiness
directive (AD):