DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-9054; Directorate Identifier 2016-NM-081-AD;
Amendment 39-18834; AD 2017-06-10]
RIN 2120-AA64

Airworthiness Directives; Bombardier, Inc. Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for certain
Bombardier, Inc. Model DHC-8-400 series airplanes. This AD was prompted
by reports of interior emergency lights remaining ``ON'' following
routine operational checks of the emergency light system. This AD
requires changing the wiring gauge for the affected emergency lights
power supplies wiring to prevent overheating in the wires. We are
issuing this AD to address the unsafe condition on these products.

DATES: This AD is effective May 1, 2017.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of May 1, 2017.

ADDRESSES: For service information identified in this final rule,
contact Bombardier, Inc., Q Series Technical Help Desk, 123 Garratt
Boulevard, Toronto, Ontario M3K 1Y5, Canada; telephone 416-375-4000;
fax 416-375-4539; email thd.qseries@aero.bombardier.com; Internet
http://www.bombardier.com. You may view this referenced service
information at the FAA, Transport Airplane Directorate, 1601 Lind
Avenue SW., Renton, WA. For information on the availability of this material at the
FAA, call 425-227-1221. It is also available on the Internet at http://www.
regulations.gov by searching for and locating Docket No. FAA-2016-9054.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov
by searching for and locating Docket No. FAA-2016-
9054; or in person at the Docket Management Facility between 9 a.m. and
5 p.m., Monday through Friday, except Federal holidays. The AD docket
contains this AD, the regulatory evaluation, any comments received, and
other information. The street address for the Docket Office (telephone
800-647-5527) is Docket Management Facility, 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: Assata Dessaline, Aerospace Engineer,
Avionics and Services Branch, ANE-172, FAA, New York Aircraft
Certification Office (ACO), 1600 Stewart Avenue, Suite 410, Westbury,
NY 11590; telephone 516-228-7301; fax 516-794-5531.

SUPPLEMENTARY INFORMATION:

Discussion

We 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-8-400 series airplanes. The NPRM published in the Federal
Register on August 30, 2016 (81 FR 59539). The NPRM was prompted by
reports of interior emergency lights remaining ``ON'' following routine
operational checks of the emergency light system. The NPRM proposed to
require changing the wiring gauge for the affected emergency lights
power supplies wiring to prevent overheating in the wires. Overheating
can damage the wire insulation, potentially causing a fire.
Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian Airworthiness Directive CF-
2016-12, effective May 11, 2016 (referred to after this as the
Mandatory Continuing Airworthiness Information, or ''the MCAI''), to
correct an unsafe condition for certain Bombardier, Inc. Model DHC-8-
400 series airplanes. The MCAI states:

There have been several reports of Interior Emergency Lights
remaining ``ON'' following routine operational checks of the
Emergency Light System. During these events, the system could not be
deactivated and the associated circuit breaker was also found
tripped. The events were caused by the overheating of the negative
interlock and ground wires at the Emergency Light System Power
Supplies.
Investigation has determined that the wire gauge of the negative
interlock and ground wiring is incompatible with the current load
experienced during the Emergency Light System operational check and
this has led to the degradation of the wiring insulation.
This [Canadian] AD is being issued to mandate the change of the
wiring gauge from 22 to 20 American wire gauge (AWG) for the
affected Emergency Lights Power Supplies wiring.

You may examine the MCAI in the AD docket on the Internet at http://www.
regulations.gov by searching for and locating Docket No. FAA-2016-9054.

Comments

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

Support for the NPRM

The Air Line Pilots Association, International, stated that it
supports the NPRM.

Requests To Refer to Updated Service Information and Provide Credit for
Previous Service Information

Horizon Air and Ryota Takeuchi requested that we revise the NPRM to
specify that the wire gauge be changed in accordance with the
Accomplishment Instructions of Bombardier Service Bulletin 84-33-12,
Revision B, dated June 28, 2016 (``SB 84-33-12, Revision B'').
Horizon Air also requested that we revise the NPRM to provide
credit for previous actions done using Bombardier Service Bulletin 84-
33-12, Revision A, dated January 19, 2016.
We agree with these requests. We have determined that SB 84-33-12,
Revision B, requires no additional actions for airplanes modified using
previous revisions. Therefore, we have revised this final rule to refer
to SB 84-33-12, Revision B. We have also revised paragraph (h) of this
AD to include credit for actions accomplished before the effective date
of this AD using Bombardier Service Bulletin 84-33-12, Revision A,
dated January 19, 2016.

Request To Reference Only the Actions Required for Compliance

Horizon Air also requested that we revise paragraph (g) of the
proposed AD to require that the wire gauge be changed in accordance
with paragraph 3.B. of the Accomplishment Instructions of SB 84-33-12,
Revision B. Horizon pointed out that incorporating the Job Set-up and
Close Out sections of the Accomplishment Instructions restricts an
operator's ability to perform other maintenance in conjunction with the
requirements of the proposed AD.
We agree with Horizon Air's request for the reason provided. We
have revised this AD to reference only the actions necessary to address
the unsafe condition specified in this AD.

Conclusion

We reviewed the relevant data, considered the comments received,
and determined that air safety and the public interest require adopting
this AD 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 correcting the unsafe condition; and
Do not add any additional burden upon the public than was
already proposed in the NPRM.
We also determined that these changes will not increase the
economic burden on any operator or increase the scope of this AD.

Related Service Information Under 1 CFR Part 51

We reviewed SB 84-33-12, Revision B. This service information
describes procedures for changing the wiring gauge for the affected
emergency lights power supplies wiring to prevent overheating in the
wires. 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

We estimate that this AD affects 52 airplanes of U.S. registry.
We estimate the following costs to comply with this AD:


Estimated Costs

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.
We are 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

We determined that 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. Is not a ``significant rule'' under the DOT Regulatory Policies
and Procedures (44 FR 11034, February 26, 1979);
3. Will not affect intrastate aviation in Alaska; and
4. 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):