DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2018-0792; Product Identifier 2018-NM-090-AD; Amendment
39-19581; AD 2019-03-29]
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
an incident of uncommanded nose wheel steering (NWS) in-service;
subsequent investigation revealed that the steering selector valve
(SSV) is susceptible to jamming in the open position due to particulate
contamination of the hydraulic system. This AD requires modifying the
left-hand hydraulic system of the NWS control system and, for certain
airplanes, torqueing the fittings on a certain tube assembly. We are issuing
this AD to address the unsafe condition on these products.

DATES: This AD is effective June 6, 2019.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of June 6, 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-2018-0792.

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- 0792;
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 Administrative 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 September 17, 2018 (83 FR 46895). The NPRM was prompted by an
incident of uncommanded NWS in-service; subsequent investigation
revealed that the SSV is susceptible to jamming in the open position
due to particulate contamination of the hydraulic system. The NPRM
proposed to require modifying the left-hand hydraulic system of the NWS
control system and, for certain airplanes, torqueing the fittings on a
certain tube assembly.
We are issuing this AD to address jamming of the SSV after
independent failure of a second component of the NWS control system,
which could result in uncommanded NWS and a possible runway excursion.
Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian AD CF-2018-11, dated April 5,
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:

An incident of uncommanded nose wheel steering occurred in-
service. Subsequent investigation revealed that the steering
selector valve (SSV) was vulnerable to jamming in the open position
due to particulate contamination of the hydraulic system. If not
corrected, a jam of the SSV, following the independent failure of a
second component of the nose wheel steering system, could result in
uncommanded nose wheel steering and a risk of runway excursion.
This [Canadian] AD requires the incorporation of a hydraulic
fluid filter in the line supplying pressure from the direct current
motor pump to the nose wheel steering system [and, for certain
airplanes, torqueing the fittings on a certain tube assembly].

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-2018-0792.

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.

Request To Correct a Date for Receipt of Comments

Bombardier requested that we correct a typographical error in the
DATES section of the proposed AD. The proposed AD stated ``We must
receive comments on this proposed AD by November 1, 20181.'' Bombardier
noted that the sentence should state ``We must receive comments on this
proposed AD by November 1, 2018.''
We acknowledge this typographical error. However, the section
containing this statement does not get carried over to this final rule.
Therefore, we have not changed this AD regarding this issue.

Request To Update Contact Information

Bombardier requested that we update their contact information in
the ADDRESSES and Related Information sections of the proposed AD.
Bombardier noted that their email and street addresses changed recently
and updating them in our final rule would allow operators to contact
Bombardier with questions.
We agree with the commenter's request for the reasons stated. We
have updated the contact information for Bombardier in the ADDRESSES
section and paragraph (k)(3) of this AD.

Request To Provide an Exception to Certain Actions

NetJets requested that we provide an exception to paragraph (g) of
the proposed AD for airplanes having serial numbers 20720 and 20722.
NetJets noted that the actions specified in Bombardier Service Bulletin
350-32-007 were incorporated in accordance with Bombardier Service
Bulletin 350-32-007 on those airplanes during production. NetJets added
that the actions required by paragraph (h) of the proposed AD would
still apply to those airplanes.
We agree to clarify. Paragraph (g) of this AD only applies to
airplanes not identified in paragraph (h) of this AD. Any airplane that
has incorporated Bombardier Service Bulletin 350-32-007 dated January
4, 2018; Revision 01, dated January 23, 2018; or Revision 02, dated
March 14, 2018, as of the effective date of this AD must complete the
actions required by paragraph (h) in this AD, but does not have to
complete the actions specified in paragraph (g) of this AD. Therefore,
this AD has not been changed with regard to this request.

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 change 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 has issued Service Bulletin 100-32-31, Revision 03; and
Service Bulletin 350-32-007, Revision 03; both dated March 27, 2018.
This service information describes procedures for modifying the left-
hand hydraulic system of the NWS control system by installing a
hydraulic filter into the hydraulic line between the direct current
motor pump and the SSV and, for certain airplanes, torqueing the
fittings on a certain tube assembly. These documents are distinct since
they apply to different airplane 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 534 airplanes of U.S. registry. We
estimate the following costs to comply with this AD:

Estimated Costs

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):