DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0338; Product Identifier 2016-NM-153-AD; Amendment
39-19103; AD 2017-23-09]
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-600-2A12 (CL-601 Variant) and CL-600-2B16
(CL-601-3A, CL-601-3R, and CL-604 Variants) airplanes. This AD was
prompted by a determination that the bushing holes on the engine mount
rib might not conform to the engineering drawings and that certain
inspections of the engine mount rib must be included in the
airworthiness limitations section (ALS) of the Instructions for
Continued Airworthiness (ICA). This AD requires revising the
maintenance or inspection program to incorporate certain airworthiness
limitation items (ALIs). We are issuing this AD to address the unsafe
condition on these products.

DATES: This AD is effective December 26, 2017.

ADDRESSES: For service information identified in this final rule,
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 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-2017-0338.

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-
0338; 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, New York Aircraft ACO Branch,
FAA, 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-600-2A12 (CL-601 Variant) and CL-600-2B16 (CL-601-3A, CL-601-
3R, and CL-604 Variants) airplanes. The NPRM published in the Federal
Register on June 14, 2017 (82 FR 27219) (``the NPRM''). The NPRM was
prompted by a determination that the bushing holes on the engine mount
rib might not conform to the engineering drawings and that certain
inspections of the engine mount rib must be included in the ALS of the
ICA. The NPRM proposed to require revising the maintenance or
inspection program to incorporate certain ALIs. We are issuing this AD
to detect and correct failure of an engine mount rib. Failure of an
engine mount rib could compromise the structural integrity of the
engine mount and could lead to subsequent detachment of an engine.
Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian Airworthiness Directive CF-
2015-09R1, dated June 29, 2015 (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 (CL-
601 Variant) and CL-600-2B16 (CL-601-3A, CL-601-3R, and CL-604
Variants) airplanes. The MCAI states:

The aeroplane manufacturer has determined that the bushing holes
on the engine mount rib may not conform to the engineering drawings.
Non-conforming bushing holes could increase loading on adjacent
fasteners, resulting in premature fatigue cracking of the engine
mount rib.
In addition, it was also discovered that the inspection
requirements for the engine mount rib were not listed in the
Airworthiness Limitations Section of the Instructions for Continued
Airworthiness.
Failure of the engine mount rib could compromise the structural
integrity of the engine mount and could lead to subsequent
detachment of an engine.
A new Time Limits/Maintenance Checks (TLMC) Airworthiness
Limitations (AWL) task is introduced to ensure that any fatigue
cracking of the engine mount rib is detected and corrected.
The original issue of this [Canadian] AD mandated the
incorporation of a new TLMC AWL task [into the maintenance or
inspection program, as applicable].
Revision 1 of this [Canadian] AD is issued to remove model CL-
600-1A11 (600) aeroplanes from the Applicability section of the
[Canadian] AD since this model was incorrectly included in the
original issue.

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-
0338.

Comments

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

Requests To Revise Applicability

Bombardier, Inc. (Bombardier) and NetJets Inc. (NetJets) requested
that we revise paragraph (c)(3) of the proposed AD. The commenters
explained that the Applicability should specify Model CL-600-2B16 (CL-
604 Variant) airplanes having serial numbers (S/Ns) 5301 through 5665
inclusive, and S/Ns 5701 through 5990 inclusive; instead of Model CL-
600-2B16 (CL-604 Variant) airplanes, having S/Ns 5301 through 5665
inclusive, and S/Ns 5701 and subsequent.
Bombardier stated that ``Challenger 650'' is a marketing
designation for Model CL-600-2B16 (604 Variant) airplanes starting at
S/N 6050, and ``Challenger 605'' is a marketing designation for Model
CL-600-2B16 (604 Variant) airplanes having S/Ns 5701 to 5990.
Bombardier and NetJets stated that future Model CL-600-2B16 (CL-604
Variant) airplanes having serial numbers subsequent to S/N 5990 do not
require the proposed actions, explaining that task 54-50-00-103
(inspections of the engine mount rib) was first incorporated into the
Time Limits/Maintenance Checks (TLMC) manual for Challenger 650
airplanes. Therefore, Bombardier asserts that operators of Challenger
650 airplanes should not be required to comply with the AD.
We agree with the commenters' requests. We have coordinated with
TCCA and have verified that Model CL- 600-2B16 (CL-604 Variant) airplanes
having serial numbers subsequent to S/N 5990 should not be subject to the
required actions. We have changed paragraph (c)(3) of this AD accordingly.

Requests To Clarify Method of Compliance (MOC) for Maintenance/
Inspection Program Revision

Bombardier requested that more details be provided on how to meet
the intent of paragraph (g) of the proposed AD, which specifies
contacting the FAA for a MOC for revising the maintenance or inspection
program to incorporate maintenance tasks. Bombardier suggested that the
AD should specify the revisions in which the tasks were incorporated
into the TLMC manual. Bombardier also suggested that this would prevent
operators with a proper TLMC from being subject to a future AD.
Bombardier stated that the AD should specify the tasks to be
incorporated in the maintenance schedule, in order to provide operators
with a sufficient level of detail on the revisions to be made to their
maintenance or inspection program.
NetJets requested that we identify the specific tasks that are to
be incorporated into the maintenance or inspection program. NetJets
noted that the MCAI provides the specific task numbers.
We partially agree. We agree that operators need to know which
actions must be incorporated into their maintenance or inspection
programs. Therefore, we have revised paragraph (g) of this AD to
identify the actions that must be incorporated.
We do not agree to identify specific TLMC revisions in this AD. The
service information specified in Note 1 to paragraph (g) of this AD
provides guidance on the required actions. However, to specify the
service information in paragraph (g) of this AD would require it to be
incorporated by reference in this AD. The service information
identified in this AD does not meet the Office of the Federal
Register's criteria for materials incorporated by reference. Therefore,
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 AD 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 correcting 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 AD.

Costs of Compliance

We estimate that this AD affects 129 airplanes of U.S. registry. We
estimate the following costs to comply with this AD:

Estimated Costs

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):