DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2018-0965; Product Identifier 2018-NM-124-AD; Amendment
39-19617; AD 2019-07-06]
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
a report that certain split ball bearings used in main landing gear
(MLG) side brace actuator assemblies are manufactured from material
that does not meet the required material properties. This AD requires
an inspection of the left and right MLG side brace actuator assemblies
and, if necessary, replacement of the split ball bearings. We are
issuing this AD to address the unsafe condition on these products.

DATES: This AD is effective May 28, 2019.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of May 28, 2019.

ADDRESSES: For service information identified in this final rule,
contact Bombardier, Inc., 200 Cote-Vertu Road West, Dorval,
Quebec H4S 2A3, Canada; North America toll-free telephone 1-866-
538-1247 or direct-dial telephone 1-514-855-2999; 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. It is also
available on the internet at http://www.regulations.gov by searching
for and locating Docket No. FAA-2018-0965.

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-2018-
0965; 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 final rule, the regulatory evaluation, any comments received, and
other information. The address for Docket Operations (phone: 800-647-
5527) is 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: Darren Gassetto, Aerospace Engineer,
Mechanical Systems and Admin Services Section, FAA, New York ACO
Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone
516-228-7323; fax 516-794-5531; email 9-avs-nyaco-cos@faa.gov.

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 November 29, 2018 (83 FR 61336). The NPRM was prompted by a report
that certain split ball bearings used in MLG side brace actuator
assemblies are manufactured from material that does not meet the
required material properties. The NPRM proposed to require an
inspection of the left and right MLG side brace actuator assemblies
and, if necessary, replacement of the split ball bearings.
We are issuing this AD to address the non-conforming split ball
bearings, which, if not corrected, could result in potentially
asymmetric MLG extension or retraction and consequent collapse of the
MLG during landing.
Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian AD CF-2018-20, dated July 27,
2018 (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:

The landing gear supplier has informed Bombardier Aerospace
about a quality escape involving Main Landing Gear (MLG) side brace
actuators that have been assembled using non-conforming split ball
bearings. The affected bearings are manufactured from material that
does not meet the required material properties. If not corrected,
this condition can result in potentially asymmetric MLG gear
extension or retraction and subsequent gear collapse during landing.
This [Canadian] AD mandates verification of the installed MLG
side brace actuator assemblies and replacement of the affected
parts.

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-2018-
0965.

Comments

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

Support for the NPRM

One commenter, Andy Ingwersen, and Flexjet indicated support for
the NPRM.

Request for Records Check To Determine MLG Side Brace Actuator Assembly
Serial Number as an Alternative Method of Compliance

Flexjet requested that an additional means of verification be
allowed for determining the serial number of the left and right MLG
side brace actuator assembly part number 40310-103. Flexjet suggested
that we add language to paragraph (g) of the proposed AD stating ``A
review of airplane maintenance records is acceptable in lieu of this
inspection if the serial number can be conclusively determined from
that review.'' Flexjet justified this request by pointing out that
similar language is used in other ADs. Flexjet explained that 20 MLG
side brace actuator assembly serial numbers are affected by Bombardier
Service Bulletin 100-32-30, dated December 18, 2017, and 217 MLG side
brace actuator assembly serial numbers are affected by Bombardier Service Bulletin
350-32-006, dated December 18, 2017, and reasoned that a logbook review
would save time and present less of a financial burden on operators.
We agree with the commenter for the reasons provided. We have
determined that a review of maintenance records is acceptable for
complying with the actions specified in paragraph (g) of this AD,
provided the serial number can be conclusively determined from that
review. We have revised paragraph (g) of this AD accordingly.

Request To Shorten Compliance Time

One commenter, Ty Smith, made a request to change the compliance
time to verify the MLG side brace actuator assembly serial number and
perform applicable on-condition actions, and we infer from the request
that the commenter wishes the compliance time to be shortened. The
commenter asserted that a compliance time of 48 months leaves a large
window of opportunity for the unsafe condition to potentially lead to a
malfunction. The commenter conceded that a certain amount of time is
needed to address the unsafe condition, but presumed that operators
have the means to address the unsafe condition sooner than the 48 month
compliance time allows.
We agree to clarify. As noted in figure 1 to paragraphs (g) and (h)
of this AD, the compliance time varies depending on the total number of
flight cycles accumulated on an airplane, with 48 months being the
longest possible compliance time. In consideration of the average
utilization rate by the affected U.S. operators, the practical aspects
of an orderly modification of the U.S. fleet during regular maintenance
periods, and the availability of required modification parts, we have
determined that the compliance times specified in figure 1 to
paragraphs (g) and (h) of this AD are appropriate. We have not changed
this AD in this regard.

Conclusion

We reviewed the relevant data, considered the comments received,
and determined that air safety and the public interest require adopting
this final rule with the changes described previously and minor
editorial changes. We have determined that these minor changes:
Are consistent with the intent that was proposed in the
NPRM for addressing the unsafe condition; and
Do not add any additional burden upon the public than was
already proposed in the NPRM.
We also determined that these changes will not increase the
economic burden on any operator or increase the scope of this final
rule.

Related Service Information Under 1 CFR Part 51

Bombardier, Inc., has issued Service Bulletin 100-32-30, dated
December 18, 2017; and Service Bulletin 350-32-006, dated December 18,
2017. This service information describes procedures for inspecting the
left and right MLG side brace actuator assemblies to verify the serial
number and replace the split ball bearings. These documents are
distinct since they apply to airplanes in different configurations.
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 468 airplanes of U.S. registry. We
estimate the following costs to comply with this 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 the required
inspection. We have no way of determining the number of aircraft that
might need these on-condition actions:

Estimated Costs of On-Condition Actions

According to the manufacturer, some or all 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 known 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 and
associated appliances to the Director of the System Oversight Division.

Regulatory Findings

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):