DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0562; Directorate Identifier 2017-NM-027-AD]
RIN 2120-AA64

Airworthiness Directives; Bombardier, Inc., Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt 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 proposed AD was prompted by a report 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 proposed AD would require replacement of
the affected RBG wheels. We are proposing this AD to address the unsafe
condition on these products.

DATES: We must receive comments on this proposed AD by August 7, 2017.

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 http://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
Bombardier, Inc., 400 Cote-Vertu Road West, Dorval, Quebec
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 Airplane Directorate, 1601
Lind Avenue SW., Renton, WA. For information on the availability of
this material at the FAA, call 425-227-1221.

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 proposed AD, the regulatory evaluation, any comments
received, and other information. The street address for the Docket
Operations office (telephone 800-647-5527) is in the ADDRESSES section.
Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Aziz Ahmed, Aerospace Engineer,
Airframe and Mechanical Systems Branch, ANE-171, FAA, New York Aircraft
Certification Office (ACO), 1600 Stewart Avenue, Suite 410, Westbury,
NY 11590; telephone 516-228-7329; fax 516-794-5531.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or
arguments about this proposed AD. Send your comments to an address
listed under the ADDRESSES section. Include "Docket No. FAA-2017-0562;
Directorate Identifier 2017-NM-027-AD" at the beginning of your
comments. We specifically invite comments on the overall regulatory,
economic, environmental, and energy aspects of this proposed AD. We
will consider all comments received by the closing date and may amend
this proposed AD based on those comments.

We will post all comments we receive, without change, to http://www.
regulations.gov, including any personal information you provide. We
will also post a report summarizing each substantive verbal contact we
receive about this proposed AD.

Discussion

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.

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.

FAA's Determination and Requirements of This Proposed AD

This product has been approved by the aviation authority of another
country, and is approved for operation in the United States. Pursuant
to our bilateral agreement with the State of Design Authority, we have
been notified of the unsafe condition described in the MCAI and service
information referenced above. We are proposing this AD because we
evaluated all pertinent information and determined an unsafe condition
exists and is likely to exist or develop on other products of these
same type designs.

Costs of Compliance

We estimate that this proposed AD affects 544 airplanes of U.S. registry.

We estimate the following costs to comply with this proposed AD:

Estimated Costs

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

According to the manufacturer, some of the costs of this proposed
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 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. 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.

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):