DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0024; Product Identifier 2018-NM-138-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-600-2A12 (601) airplanes. This
proposed AD was prompted by a report of damage to the anti-rotation tab
on a main landing gear (MLG) side brace fitting due to the installation
of an incorrect side brace fitting shaft. This proposed AD would
require an inspection of the MLG side brace fitting for damage, a
verification of the side brace fitting shaft part number, and
replacement of the side brace fitting shaft if necessary. It would also
require the installation of an anti-rotation bracket. We are proposing
this AD to address the unsafe condition on these products.

DATES: We must receive comments on this proposed AD by April 15, 2019.

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 service information at the FAA,
Transport Standards Branch, 2200 South 216th St., Des Moines, WA. For
information on the availability of this material at the FAA, call 206-
231-3195.

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-2019-0024;
or in person at Docket Operations between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays. The AD docket contains
this NPRM, the regulatory evaluation, any comments received, and other
information. The street address for Docket Operations (phone: 800-647-
5527) is in the ADDRESSES section. Comments will be available in the AD
docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Kristopher Greer, Aerospace Engineer,
Aviation Safety Section AIR-7B1, Boston ACO Branch, FAA, 1200 District
Avenue, Burlington, MA 01803; telephone 781-238-7799.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under the ADDRESSES section. Include "Docket No. FAA-2019-0024;
Product Identifier 2018-NM-138-AD" at the beginning of your comments.
We specifically invite comments on the overall regulatory, economic,
environmental, and energy aspects of this NPRM. We will consider all
comments received by the closing date and may amend this NPRM because
of 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 NPRM.

Discussion

Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian AD CF-2018-19, dated July 20,
2018 (referred to after this as the Mandatory Continuing Airworthiness
Information, or "the MCAI"), to correct an unsafe condition for
certain Bombardier, Inc., Model CL-600-2A12 (601) airplanes. The MCAI
states:

There has been a report of damage to the anti-rotation tab on a
Main Landing Gear (MLG) Side Brace fitting. Investigation of the
report revealed that a Challenger model CL600 MLG Side Brace shaft
had been installed on a Challenger model CL601 Side Brace fitting.
Due to the difference in size, this will result in changes to the
way the load is transferred between the shaft and the MLG Side Brace
fitting and may result in premature cracking of the MLG Side Brace
fitting. This condition, if not corrected, could lead to the
collapse of the MLG resulting in structural damage to the wing spar
and fuel tank.

This [Canadian] AD mandates an inspection of the MLG Side Brace
fitting and shaft to verify that the correct shaft part number (P/N)
is installed and the fitting is not damaged [damage includes
cracking, scratches, gouges, corrosion, defects, and incorrect inner
diameter tolerance]. If the Challenger CL600 shaft is installed,
this AD mandates replacement with the correct Challenger model CL601
part. If the correct P/N is found installed, this [Canadian] AD also
mandates the installation of a bracket to prevent the incorrect part
from being installed in the future.

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-2019-
0024.

Related Service Information Under 1 CFR Part 51

Bombardier has issued Service Bulletin 601-0624, Revision 2, dated
January 29, 2018. This service information describes procedures for
inspecting the MLG side brace fitting and side brace fitting shaft,
installing a replacement side brace fitting shaft if necessary, and
installing an anti-rotation bracket.

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

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 the relevant information and determined the unsafe
condition described previously is likely to exist or develop on other
products of the same type design.

Proposed Requirements of This NPRM

This proposed AD would require accomplishing the actions specified
in the service information described previously.

Costs of Compliance

We estimate that this proposed AD affects 9 airplanes of U.S.
registry. We estimate the following costs to comply with this proposed
AD:

Estimated Costs for Required Actions

We estimate the following costs to do any necessary on-condition
actions that would be required based on the results of any required
actions. We have no way of determining the number of aircraft that
might need these on-condition actions:

Estimated Costs of On-Condition Actions

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 proposed 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 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):