DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0124; Directorate Identifier 2016-NM-166-AD;
Amendment 39-18911; AD 2017-11-12]
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 BD-100-1A10 airplanes. This AD was prompted by
several reports of nose wheel steering failures in service. This AD
requires a part verification and replacement of certain steering
manifolds. We are issuing this AD to address the unsafe condition on
these products.

DATES: This AD is effective July 11, 2017.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of July 11, 2017.

ADDRESSES: For service information identified in this final rule,
contact Bombardier, Inc., 400 C[ocirc]te-Vertu Road West, Dorval,
Qu[eacute]bec H4S 1Y9, Canada; telephone 514-855-5000; fax 514-855-
7401; email thd.crj@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-2017-0124.

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-2017-
0124; 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 BD-100-1A10 airplanes. The NPRM published in the Federal Register
on February 28, 2017 (82 FR 12071). The NPRM was prompted by several
reports of nose wheel steering failures in service. The NPRM proposed
to require a part verification and replacement of certain steering
manifolds. We are issuing this AD to prevent moisture from entering the
electrical stage of the electro-hydraulic servo valve (EHSV), which, in
combination with a steering selector valve failure, could lead to
uncommanded nose wheel steering, and a consequent runway excursion at
high speed.
Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian Airworthiness Directive CF-
2016-24, dated August 19, 2016 (referred to after this as the Mandatory
Continuing Airworthiness Information, or ``the MCAI''), to correct an
unsafe condition for certain Bombardier, Inc., Model BD-100-1A10
airplanes. The MCAI states:

Several cases of nose wheel steering failures have been reported
in service. In one case, the aeroplane experienced uncommanded nose
wheel steering, resulting in a runway excursion.
Investigations found the presence of moisture inside the
electrical stage of the electro-hydraulic servo valve (EHSV) unit,
which resulted in low insulation resistance and corrosion. This
condition, in combination with a steering selector valve failure,
could result in uncommanded nose wheel steering, which could lead to
a runway excursion at high speed.
This [Canadian] AD mandates the replacement of the steering
manifold to provide better moisture ingress protection of the EHSV.

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-2017-0124.

Comments

We gave the public the opportunity to participate in developing
this AD. We received no comments on the NPRM or on the determination of
the cost to the public.

Conclusion

We reviewed the relevant data and determined that air safety and
the public interest require adopting this AD as proposed except for
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.

Related Service Information Under 1 CFR Part 51

We reviewed Bombardier Service Bulletin 100-32-25, Revision 01,
dated June 30, 2015. This service information describes procedures for
a one-time verification of the steering manifold part number and
replacement of the steering manifold and mod plate. 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 161 airplanes of U.S. registry.
We estimate the following costs to comply with this AD:

Estimated Costs

According to the manufacturer, some of the costs of this AD may be
covered under warranty, thereby reducing the cost impact on affected
individuals. We do not control warranty coverage for affected
individuals. As a result, we have included all costs in our cost
estimate.

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):