DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0530; Directorate Identifier 2017-NM-012-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 supersede Airworthiness Directive (AD) 2016-11-
02, which applies to all Bombardier, Inc., Model CL-600-2C10 (Regional
Jet Series 700, 701, & 702) airplanes; Model CL-600-2D15 (Regional Jet
Series 705) airplanes; Model CL-600-2D24 (Regional Jet Series 900)
airplanes; and Model CL-600-2E25 (Regional Jet Series 1000) airplanes.
AD 2016-11-02 requires repetitive inspections of the upper and lower
engine pylons for protruding, loose, or missing fasteners; and repair
if necessary. Since we issued AD 2016-11-02, we have determined that a
terminating action is necessary to address the unsafe condition. This
proposed AD would continue to require the repetitive inspections of the
upper and lower engine pylons for protruding, loose, or missing
fasteners; and repair if necessary. This proposed AD would also require
replacement of affected fasteners, which terminates the inspections. We
are proposing this AD to address the unsafe condition on these
products.

DATES: We must receive comments on this proposed AD by July 27, 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; telephone 514-855-5000; fax 514 855-7401; email
thd.crj@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-2017-0530;
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, 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-2017-0530;
Directorate Identifier 2017-NM-012-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

On May 17, 2016, we issued AD 2016-11-02, Amendment 39-18529 (81 FR
33371, May 26, 2016) ("AD 2016-11-02"), for all Bombardier, Inc.,
Model CL-600-2C10 (Regional Jet Series 700, 701, & 702) airplanes;
Model CL-600-2D15 (Regional Jet Series 705) airplanes; Model CL-600-
2D24 (Regional Jet Series 900) airplanes; and Model CL-600-2E25
(Regional Jet Series 1000) airplanes. AD 2016-11-02 was prompted by
reports of loose or missing fasteners on the upper and lower engine
pylon structure common to the upper and lower pylon skin panels and
engine thrust fitting. AD 2016-11-02 requires repetitive detailed
visual inspections of the upper and lower engine pylons for protruding,
loose, or missing fasteners; and repair, including applicable related
investigative and corrective actions, if necessary. We issued AD 2016-
11-02 to detect and correct protruding, loose, or missing fasteners,
which could result in structural failure of the engine pylons.

Since we issued AD 2016-11-02, we have determined that a
terminating action is necessary to address the unsafe condition. In
addition, Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian Airworthiness Directive CF-
2016-10R1, dated July 8, 2016 (referred to after this as the Mandatory
Continuing Airworthiness Information, or "the MCAI"), to correct an
unsafe condition for all Bombardier, Inc., Model CL-600-2C10 (Regional
Jet Series 700, 701, & 702) airplanes; Model CL-600-2D15 (Regional Jet
Series 705) airplanes; Model CL-600-2D24 (Regional Jet Series 900)
airplanes; and Model CL-600-2E25 (Regional Jet Series 1000) airplanes.
The MCAI states:

There have been several reported findings of loose or missing
Hi-Lite fasteners and collars on the left hand (L/H) and right hand
(R/H) upper and lower engine pylon structure common to the upper and
lower pylon skin panels and engine thrust fitting. Missing fasteners
in these areas are shown to significantly reduce the safety margins
and could result in a structural failure of the engine pylon.

Bombardier, as an interim corrective action issued a new
Aircraft Maintenance Manual (AMM) task for detailed inspection of
the engine pylon rib and skin fasteners to inspect for protruding,
loose or missing fasteners and rectify any discrepancies noted in
accordance with a Repair Engineering Order (REO). The original
version of this [Canadian] AD, CF-2016-10, mandated the subject
inspection and necessary rectification.

Bombardier has since issued Service Bulletin (SB) 670BA-54-007
to replace all affected fasteners with interference fit fasteners
[including applicable related investigative and corrective actions],
as terminating action for the mandated inspection requirement.
[Canadian] AD CF-2016-10 is now being revised to mandate compliance
with SB 670BA-54-007.

Related investigative actions include measurements of the attach holes
in the engine pylon upper structure and special detailed visual
inspections for cracks in the engine pylon structure. Corrective
actions include repair. 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-2017-0530.

Related Service Information Under 1 CFR Part 51

Bombardier, Inc., issued Service Bulletin 670BA-54-007, dated May
13, 2016. The service information describes procedures for replacing
fasteners and collars, including applicable related investigative and
corrective actions.

Bombardier, Inc., also issued Repair Engineering Order 670-54-51-
034, "Repair for Missing or Loose/Protruding Fasteners in Upper and
Lower Pylon Skins FS 1088-FS 1098, PBL 69.3 L & RHS," Revision A,
dated April 20, 2016. The service information describes procedures for
repair, including applicable related investigative and corrective
actions.

In addition, Bombardier, Inc., issued Temporary Revision 54-0007,
dated March 8, 2016, to the CRJ700/900/1000 AMM. The service
information describes procedures for a detailed visual inspection for
protruding, loose, or missing fasteners of the left-hand and right-hand
upper and lower engine pylons.

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 273 airplanes of U.S.
registry.

Estimated Costs

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

On-Condition 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 for the
on-condition repairs.

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 removing Airworthiness Directive (AD)
2016-11-02, Amendment 39-18529 (81 FR 33371, May 26, 2016), and adding
the following new AD: