DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0562; Product Identifier 2017-NM-027-AD; Amendment
39-19088; AD 2017-22-08]
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 CL-600-2C10 (Regional Jet Series 700, 701, &
702), Model CL-600-2D15 (Regional Jet Series 705), Model CL-600-2D24
(Regional Jet Series 900), and Model CL-600-2E25 (Regional Jet Series
1000) airplanes. This AD was prompted by a report indicating that a
number of rubber bull gear (RBG) wheels installed in the horizontal
stabilizer trim actuator (HSTA) were manufactured using an incorrect
material specification. This AD requires replacement of the affected
RBG wheels. We are issuing this AD to address the unsafe condition on
these products.

DATES: This AD is effective December 11, 2017.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of December 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; Widebody Customer Response Center North
America toll-free telephone 1-866-538-1247 or direct-dial telephone 1-
514-855-2999; fax 514-855-7401; email ac.yul@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-2017-0562.

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-
0562; 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: Aziz Ahmed, Aerospace Engineer,
Airframe and Mechanical Systems Section, FAA, New York ACO Branch, 1600
Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7329;
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 CL-600-2C10 (Regional Jet Series 700, 701, & 702), Model CL-600-
2D15 (Regional Jet Series 705), Model CL-600-2D24 (Regional Jet Series
900), and Model CL-600-2E25 (Regional Jet Series 1000). The NPRM
published in the Federal Register on June 21, 2017 (82 FR 28266) (``the
NPRM''). The NPRM was prompted by a report indicating that a number of
RBG wheels installed in the HSTA were manufactured using an incorrect
material specification. The NPRM proposed to require replacement of the
affected RBG wheels. We are issuing this AD to prevent premature wear-
out of the teeth of the RBG wheels, which could cause difficulties in
maneuvering the airplane.
Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian Airworthiness Directive CF-
2016-22, dated June 24, 2016 (referred to after this as the Mandatory
Continuing Airworthiness Information, or ``the MCAI''), to correct an
unsafe condition for certain Bombardier, Inc., Model CL-600-2C10
(Regional Jet Series 700, 701, & 702), Model CL-600-2D15 (Regional Jet
Series 705), Model CL-600-2D24 (Regional Jet Series 900), and Model CL-
600-2E25 (Regional Jet Series 1000) airplanes. The MCAI states:

An inspection by the vendor revealed that a number of Rubber
Bull Gear (RBG) Wheels installed in the Horizontal Stabilizer Trim
Actuator (HSTA) of the CL-600-2C10, CL-600-2D15, CL-600-2D24 and CL-
600-2E25 aeroplanes were manufactured from the incorrect material
specification. The use of the incorrect material specification has a
direct impact on the RBG Wheels life limit. The teeth of these non-
conforming RBG Wheels may experience premature wear out and if not
corrected, this condition could result in difficulties in
maneuvering the aeroplane.
This [Canadian] AD mandates replacement of the RBGs whose wheels
have been made using an incorrect material specification.

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-
0562.

Comments

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

Request To Revise Compliance Times

Air Line Pilots Association, International (ALPA) requested that we
review and revise the compliance times specified in the proposed AD to
reflect flight hours rather than flight cycles, and to align the times
with a previous AD, AD 2011-12-06, Amendment 39-16713 (76 FR 33982,
June 10, 2011) (``AD 2011-12-06''). The commenter asserted that the
compliance times in AD 2011-12-06 were more conservative than what is
written in the proposed AD, and that for a component with a known
material defect that is continuously used throughout the duration of
any given flight, flight hours rather than flight cycles would be a
more appropriate metric to measure compliance time.
We disagree with the commenter's proposed change. We reviewed
TCCA's evaluation of the compliance times, and determined that they are
appropriate to mitigate the unsafe condition. We have not received any
data to demonstrate otherwise. In addition, the compliance times in AD
2011-12-06 are also based on flight cycles instead of flight hours.
Therefore, have not changed this AD in this regard.

Conclusion

We reviewed the relevant data, considered the comment received, 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 670BA-27-072, Revision A,
dated October 26, 2016. This service information describes procedures
for identification of affected HSTAs, and replacement if necessary.
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 544 airplanes of U.S. registry.
We estimate the following costs to comply with this AD:

Estimated Costs

¹We have received no definitive data that would enable us to provide cost
estimates for the parts cost specified in this AD.

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.
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 adding the following new airworthiness
directive (AD):