DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0775; Product Identifier 2017-NM-048-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) 2016-25-
18, for certain Bombardier, Inc., Model BD-700-1A10 and BD-700-1A11
airplanes. AD 2016-25-18 requires an inspection for discrepancies of
the attachment points of the links between the engine rear mount
assemblies, and corrective actions if necessary. Since we issued AD
2016-25-18, we have determined that replacement of certain nuts and
bolts in the engine rear mount assemblies is necessary. This proposed
AD would require an inspection of certain attachment points, corrective
action if necessary, and replacement of certain bolts and nuts in the
engine rear mount assemblies. This proposed AD also adds airplanes to
the applicability. We are proposing this AD to address the unsafe
condition on these products.

DATES: We must receive comments on this proposed AD by September 29, 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
Standards Branch, 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-2017-0775;
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, Airframe Engineer,
Airframe and Mechanical Systems Section, FAA, New York ACO Branch, 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 proposal. Send your comments to an address listed
under the ADDRESSES section. Include "Docket No. FAA-2017-0775;
Product Identifier 2017-NM-048-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 December 2, 2016, we issued AD 2016-25-18, Amendment 39-18744
(81 FR 90961, December 16, 2016) ("AD 2016-25-18"), for certain
Bombardier, Inc., Model BD-700-1A10 and BD-700-1A11 airplanes. AD 2016-
25-18 was prompted by a report indicating that during maintenance, an
engine mount pin was found backed out of the rear mount link, and the
associated retaining bolt was also found fractured. AD 2016-25-18
requires an inspection for discrepancies of the attachment points of
the links between the engine rear mount assemblies, and corrective
actions if necessary. We issued AD 2016-25-18 to detect and correct
broken engine attachment hardware, which could result in separation of
an engine from the airplane.

Since we issued AD 2016-25-18, we have determined that replacement
of certain nuts and bolts in the engine rear mount assemblies is
necessary.

Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian AD CF-2016-23R1, dated
February 20, 2017 (referred to after this as the Mandatory Continuing
Airworthiness Information, or "the MCAI"), to correct an unsafe
condition for certain Bombardier, Inc., Model BD-700-1A10 and BD-700-
1A11 airplanes. The MCAI states:

Bombardier reported that during maintenance of a BD-700
aeroplane, the engine mount pin, part number (P/N) BRR15838, was
found backed out of the rear mount link. The retaining bolt, P/N
AS54020, which passes through the engine mount pin was also found
fractured at the groove which holds the locking spring. An
investigation revealed the most probable root cause of failure to be
a single axial tension static overload, with no evidence of fatigue
contributing to the failure.

The above condition if not detected, may result in the loss of
engine attachment to the airframe.

As an interim corrective action, Bombardier issued Service
Bulletins (SBs) 700-71-002, 700-71-6002, 700-71-5002,
and 700-1A11-71-002 to inspect the attachment points of the links
between the engine rear mount assemblies, and install replacement
hardware if required.

The original version of this [Canadian] AD was issued to mandate
incorporation of the above Bombardier SBs to inspect and maintain
integrity of the affected engine rear mount assembly.

Revision 1 of this [Canadian] AD is issued to mandate
incorporation of the Bombardier SBs 700-71-003, 700-71-6003, 700-71-
5003, and 700-1A11-71-003 to replace the existing bolts and self-
locking nuts with new bolts and nuts, as a final corrective action.

The MCAI also adds airplanes having serial numbers 9764, 9766, and 9771
through 9785 inclusive to the applicability. Those airplanes are also
affected by the identified unsafe condition. 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-2017-0775.

Related Service Information Under 1 CFR Part 51

Bombardier has issued the following service information.

Bombardier Service Bulletin 700-71-002, Revision 01, dated
June 30, 2016.

Bombardier Service Bulletin 700-71-5002, Revision 01,
dated June 30, 2016.

Bombardier Service Bulletin 700-71-6002, Revision 01,
dated June 30, 2016.

Bombardier Service Bulletin 700-1A11-71-002, Revision 01,
dated June 30, 2016.

This service information describes procedures for an inspection for
discrepancies of the attachment points of the links between the engine
rear mount assemblies and corrective actions. These documents are
distinct since they apply to different airplane models and serial
numbers.

Bombardier has also issued the following service information. The
service information describes procedures for nut and bolt replacement.
These documents are distinct since they apply to different airplane
models and serial numbers.

Bombardier Service Bulletin 700-71-003, dated December 5, 2016.

Bombardier Service Bulletin 700-71-5003, dated December 5, 2016.

Bombardier Service Bulletin 700-71-6003, dated December 5, 2016.

Bombardier Service Bulletin 700-1A11-71-003, dated December 5, 2016.

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 the same
type design.

Costs of Compliance

We estimate that this proposed AD affects 97 airplanes of U.S. registry.

The actions required by AD 2016-25-18, and retained in this
proposed AD take about 1 work-hour per product, at an average labor
rate of $85 per work-hour. Based on these figures, the estimated cost
of the actions that are required by AD 2016-25-18 is $85 per product.

The retained on-condition costs in this proposed AD take about 2
work-hours per product, at an average labor rate of $85 per work-hour.
Required parts cost about $730 per product. Based on these figures, the
estimated cost of the on-condition actions that are required by AD
2016-25-18 is $900 per product.

We have received no definitive data that would enable us to provide
cost estimates for other retained on-condition actions specified in AD
2016-25-18.

We also estimate that it would take about 4 work-hours per product
to comply with the basic requirements of this proposed AD. The average
labor rate is $85 per work-hour. Required parts would cost up to
$14,940 per product. Based on these figures, we estimate the cost of
this proposed AD on U.S. operators to be up to $1,482,160, or up to
$15,280 per product.

We have received no definitive data that would enable us to provide
cost estimates for the on-condition actions specified in this proposed
AD.

According to the manufacturer, some of the costs of this proposed
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 available 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 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 removing Airworthiness Directive (AD)
2016-25-18, Amendment 39-18744 (81 FR 90961, December 16, 2016), and
adding the following new AD: