DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-9575; Product Identifier 2016-NM-168-AD; Amendment
39-18992; AD 2017-17-02]
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 superseding Airworthiness Directive (AD) 2014-20-09,
which applied to certain Bombardier, Inc., Model DHC-8-400 series
airplanes. AD 2014-20-09 required an inspection for missing clamps that
are required to provide positive separation between the alternating
current (AC) feeder cables and the hydraulic line of the landing gear
alternate extension, and related investigative and corrective actions
if necessary. This new AD requires removing airplanes from the AD
applicability. This AD was prompted by reports of missing clamps that
are required to provide positive separation between the AC feeder
cables and the hydraulic line of the landing gear alternate extension.
We are issuing this AD to address the unsafe condition on these
products.

DATES: This AD is effective September 25, 2017.

The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of September 25, 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 Standards Branch, 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-2016-9575.

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-2016-9575; 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 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 Administrative Services Section, FAA, New York ACO Branch,
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 to supersede AD 2014-20-09, Amendment 39-17982 (79 FR 59630,
October 3, 2014) ("AD 2014-20-09"). AD 2014-20-09 applied to certain
Bombardier, Inc., Model DHC-8-400 series airplanes. The NPRM published
in the Federal Register on February 22, 2017 (82 FR 11325). The NPRM
was prompted by reports of missing clamps that are required to provide
positive separation between the AC feeder cables and the hydraulic line
of the landing gear alternate extension. The NPRM proposed to continue
to require an inspection for missing clamps that are required to
provide positive separation between the AC feeder cables and the
hydraulic line of the landing gear alternate extension, and related
investigative and corrective actions if necessary. We are issuing this
AD to detect and correct chafing of the AC feeder cable. A chafed and
arcing AC feeder cable could puncture the adjacent hydraulic line,
which, in combination with the use of the alternate extension, could
result in an in-flight fire.

Since we issued AD 2014-20-09, the FAA has determined that certain
airplane serial numbers that are in a pre-modification MS 4M153025
configuration have sufficient space between the AC feeder cables and
the landing gear alternate extension hydraulic line, and do not pose an
in-flight fire risk. Therefore, these airplanes are not subject to the
identified unsafe condition.

Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian Airworthiness Directive CF-
2013-16R1, effective July 26, 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:

During production checks, it was found that the appropriate
clamps required to provide positive separation between the AC feeder
cables and the hydraulic line of the landing gear alternate
extension were omitted. The AC feeder cable could sag and be in
direct contact with the swage fitting of the landing gear alternate
extension hydraulic line, resulting in chafing of the AC feeder
cable. The chafed and arcing AC feeder cable could puncture the
adjacent hydraulic line. In combination with the use of the
alternate extension system, this could result in an in-flight fire.

The original issue of this [Canadian] AD was issued to mandate
the incorporation of [Bombardier] service bulletin (SB) 84-24-53 to
* * * [do a general visual inspection for the presence of correctly
installed clamps] and rectify, as necessary, for proper clamp
installation.

Bombardier, Inc. has revised [Bombardier] SB 84-24-53 to remove
serial numbers 4001 through 4034 from the Effectivity section, as it
was determined that these serial numbers are Pre-Mod MS 4M153025,
which allowed sufficient space between the AC feeder cables and the
landing gear alternate extension hydraulic line to not pose an in-
flight fire risk. Accordingly, revision 1 of this [Canadian] AD is
issued to revise the Applicability section to reflect the
Effectivity changes in [Bombardier] SB 84-24-53 Revision B, dated 10
September 2015.

The related investigative action is a general visual inspection of
the AC power feeder cables and the hydraulic line of the landing gear
alternate extension for damage due to chafing. The corrective actions
include repair of chafed parts and replacement of missing clamps. 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-
9575.

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.

Request To Reference Only the Actions Required for Compliance

Horizon Air requested that paragraph (g) of the proposed AD
reference only the actions required for compliance. Horizon Air stated
that incorporating the service bulletin job set-up and close-out
sections as a requirement of the AD restricts an operator's ability to
perform other maintenance in conjunction with the incorporation of
Bombardier Service Bulletin 84-24-53, Revision B, dated September 10,
2015. Horizon Air asserted that only paragraph 3.B., "Procedure," in
the Accomplishment Instructions of Bombardier Service Bulletin 84-24-
53, Revision B, dated September 10, 2015, should be referenced.

We agree with Horizon Air's request to exclude the "Job Set-up"
and "Close Out" sections of Bombardier Service Bulletin 84-24-53,
Revision B, dated September 10, 2015, for the reasons provided. We have
revised paragraph (g) of this AD to require accomplishment of paragraph
3.B., "Procedure," of the Accomplishment Instructions of Bombardier
Service Bulletin 84-24-53, Revision B, dated September 10, 2015.

Request To Allow Credit for Previous Actions Up to the Effective Date
of This AD

Horizon Air requested that the proposed AD be changed to allow
credit for previous actions in accordance with Bombardier Service
Bulletin 84-24-53, dated May 11, 2012; or Bombardier Service Bulletin
84-24-53, Revision A, dated May 16, 2013; either up to the effective
date of this AD; or within 6,000 flight hours or 36 months from
November 7, 2014 (the effective date of AD 2014-20-09), whichever
occurs first. Horizon Air stated that paragraph (h) of the proposed AD
only allows credit for actions performed before November 7, 2014.
Horizon Air noted that the compliance for AD 2014-20-09 is within 6,000
flight hours or 36 months after the effective date of November 7, 2014
(and AD 2014-20-09 specifies that the actions be done in accordance
with Bombardier Service Bulletin 84-24-53, Revision A, dated May 16,
2013).

We partially agree. We agree that credit for the actions required
by paragraph (g) of this AD done using Bombardier Service Bulletin 84-
24-53, Revision A, dated May 16, 2013, should be allowed up until the
effective date of this AD. However, we do not agree to allow credit for
Bombardier Service Bulletin 84-24-53, dated May 11, 2012, beyond
November 7, 2014. AD 2014-20-09 only gives credit for Bombardier
Service Bulletin 84-24-53, dated May 11, 2012, before November 7, 2014.
We have revised paragraph (h) of this AD accordingly.

Explanation of Change Made in This AD

We have revised paragraph (g) of this AD to remove the statement
that only Bombardier Service Bulletin 84-24-53, Revision B, dated
September 10, 2015, may be used after the effective date of this AD
because that statement is not necessary in this AD.

Conclusion

We reviewed the available data, including 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 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.

Related Service Information Under 1 CFR Part 51

We reviewed Bombardier Service Bulletin 84-24-53, Revision B, dated
September 10, 2015. The service information describes procedures for a
general visual inspection for installation of clamps between the AC
feeder cables and hydraulic line of the landing gear alternate
extension, and related investigative and corrective actions. 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

This AD merely removes certain airplanes from the applicability of
this AD, and, therefore, adds no new actions or economic burden.

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.

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 to the Director
of the System Oversight Division.

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 removing Airworthiness Directive (AD)
2014-20-09, Amendment 39-17982 (79 FR 59630, October 3, 2014), and
adding the following new AD: