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PROPOSED AD BOMBARDIER, INC.: Docket No. FAA-2018-0634; Product Identifier 2018-NM-050-AD.
(a) COMMENTS DUE DATE

    We must receive comments by August 27, 2018.

(b) AFFECTED ADS

    None.

(c) APPLICABILITY

    This  AD  applies  to the  Bombardier,  Inc.,  airplanes specified  in
    paragraphs (c)(1), (c)(2), and (c)(3) of this AD, certificated in  any
    category.

(1) Model  CL-600-2C10  (Regional  Jet  Series 700, 701 & 702)  airplanes,
    serial numbers 10003 through 10345 inclusive.

(2) Model CL-600-2D15 (Regional Jet Series 705) airplanes and Model CL-600
    -2D24 (Regional Jet Series 900) airplanes serial numbers 15001 through
    15429 inclusive.

(3) Model CL-600-2E25 (Regional Jet Series 1000) airplanes, serial numbers
    19001 through 19052 inclusive.

(d) SUBJECT

    Air Transport Association (ATA) of America Code 32, Main landing gear.

(e) REASON

    This AD was prompted by reports of a fractured main landing gear (MLG)
    orifice  support tube  (OST).  We  are issuing  this AD  to address  a
    fractured MLG OST, which can lead to structural damage to the airplane
    and collapse of the MLG.

(f) COMPLIANCE

    Comply  with this  AD within  the compliance  times specified,  unless
    already done.

(g) REPLACEMENT

    Within the compliance times specified in figure 1 to paragraph (g)  of
    this AD: Replace each MLG  OST, in accordance with the  Accomplishment
    Instructions  of  Bombardier Service Bulletin  SB 670BA-32-058,  dated
    September 26, 2016.
    ______________________________________________________________________
           FIGURE 1 TO PARAGRAPH (G) OF THIS AD — COMPLIANCE TIMES        
    ______________________________________________________________________
    AIRPLANE MODELS                               COMPLIANCE TIME
    ______________________________________________________________________
    CL-600-2C10 (Regional Jet Series      Within 21,000 flight cycles from
    700, 701 & 702) airplanes             the effective date of this AD or
                                          before MLG OST(s) accumulate
                                          40,000 total flight cycles,
                                          whichever occurs first

    CL-600-2D15 (Regional Jet Series      Within 20,000 flight cycles from
    705) airplanes and CL-600-2D24        the effective date of this AD or
    (Regional Jet Series 900) air-        before MLG OST(s) accumulate
    planes equipped with MLG OST(s)       29,100 total flight cycles,
    that have accumulated fewer than      whichever occurs first
    23,100 flight cycles as of the
    effective date of this AD

    CL-600-2D15 (Regional Jet Series      Within 6,000 flight cycles from
    705) airplanes and CL-600-2D24        the effective date of this AD
    (Regional Jet Series 900) air-
    planes equipped with MLG OST(s)
    that have accumulated 23,100
    flight cycles or more as of the
    effective date of this AD

    CL-600-2E25 (Regional Jet Series      Before MLG OST(s) accumulate
    1000) airplanes                       20,000 total flight cycles
    ______________________________________________________________________

(h) MAINTENANCE OR INSPECTION PROGRAM REVISION

    Within  90  days after  the  effective date  of  this AD,  revise  the
    maintenance  or  inspection  program,  as  applicable,  to incorporate
    Bombardier Temporary Revision ALI-0593,  dated December 18, 2017.  The
    initial  compliance  time  for accomplishing  the  actions  is at  the
    applicable time specified  in Bombardier Temporary  Revision ALI-0593,
    dated December 18, 2017; or within 90 days after the effective date of
    this AD; whichever occurs later.

(i) NO ALTERNATIVE ACTIONS OR INTERVALS

    After  the  maintenance  or inspection  program  has  been revised  as
    required by paragraph  (h) of this  AD, no alternative  actions (e.g.,
    inspections) or intervals may be used unless the actions or  intervals
    are  approved  as  an  alternative  method  of  compliance  (AMOC)  in
    accordance with the procedures  specified in paragraph (j)(1)  of this
    AD.

(j) OTHER FAA AD PROVISIONS

    The following provisions also apply to this AD:

(1) Alternative Methods of Compliance (AMOCs):  The Manager,  New York ACO
    Branch,  FAA, has  the authority  to approve  AMOCs  for  this AD,  if
    requested using the  procedures found in  14 CFR 39.19.  In accordance
    with 14 CFR  39.19, send your  request to your  principal inspector or
    local Flight  Standards District  Office, as  appropriate. If  sending
    information directly to the manager of the certification office,  send
    it to ATTN: Program  Manager, Continuing Operational Safety,  FAA, New
    York ACO Branch, 1600 Stewart  Avenue, Suite 410, Westbury, NY  11590;
    telephone 516-228-7300;  fax 516-794-5531.  Before using  any approved
    AMOC,  notify  your  appropriate  principal  inspector,  or  lacking a
    principal  inspector,  the  manager  of  the  local  flight  standards
    district office/certificate holding district office.

(2) Contacting the Manufacturer:  For any requirement in this AD to obtain
    corrective  actions   from  a   manufacturer,  the   action  must   be
    accomplished using  a method  approved by  the Manager,  New York  ACO
    Branch, FAA; or Transport Canada Civil Aviation (TCCA); or Bombardier,
    Inc.'s TCCA  Design Approval  Organization (DAO).  If approved  by the
    DAO, the approval must include the DAO-authorized signature.

(k) RELATED INFORMATION

(1) Refer   to   Mandatory  Continuing  Airworthiness  Information  (MCAI)
    Canadian  AD   CF-2018-02,  dated   January  16,   2018,  for  related
    information. This MCAI may be found  in the AD docket on the  internet
    at http://www.regulations.gov by searching for and locating Docket No.
    FAA-2018-0634.

(2) For  more information  about this AD,  contact  Aziz Ahmed,  Aerospace
    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; email 9-avs-nyaco-cos@faa.gov.

(3) For service information identified in this AD, contact Bombardier, Inc
    400 Cote-Vertu Road West,  Dorval,  Quebec H4S 1Y9,  Canada;  Widebody
    Customer Response Center North America  toll-free  telephone  866-538-
    1247 or direct-dial telephone 514-855-2999; fax 514-855-7401; 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 availabil-
    ity of this material at the FAA, call 206-231-3195.

Issued  in  Des  Moines, Washington,  on  July 3, 2018.  Michael Kaszycki,
Acting  Director,  System   Oversight  Division,  Aircraft   Certification
Service.

DATES: We must receive comments on this proposed AD by August 27, 2018.
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2018-0634; Product Identifier 2018-NM-050-AD]
RIN 2120-AA64

Airworthiness Directives; Bombardier, Inc., Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: We propose to adopt a new airworthiness directive (AD) for
certain 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. This proposed
AD was prompted by reports of a fractured main landing gear (MLG)
orifice support tube (OST). This proposed AD would require replacing
the MLG OST, and revising the maintenance or inspection program, as
applicable, to incorporate new or more restrictive maintenance
requirements and airworthiness limitations. We are proposing this AD to
address the unsafe condition on these products.

DATES: We must receive comments on this proposed AD by August 27, 2018.

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; Widebody Customer Response Center North America toll-
free telephone 866-538-1247 or direct-dial telephone 514-855-2999; fax
514-855-7401; 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.

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-
0634; 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 NPRM, the regulatory evaluation, any comments received, and other
information. The street address for Docket Operations (phone: 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 Section, FAA, New York ACO Branch, 1600
Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7329;
fax 516-794-5531; email 9-avs-nyaco-cos@faa.gov.

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-2018-0634;
Product Identifier 2018-NM-050-AD" at the beginning of your comments.
We specifically invite comments on the overall regulatory, economic,
environmental, and energy aspects of this NPRM. We will consider all
comments received by the closing date and may amend this NPRM because
of 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 NPRM.

Discussion

Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian AD CF-2018-02, dated January
16, 2018 (referred to after this as the Mandatory Continuing
Airworthiness Information, or "the MCAI"), to correct an unsafe
condition for certain Bombardier, Inc., Model CL-600-2C10 (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:

Five cases of fractured Main Landing Gear (MLG) Orifice Support
Tube (OST) have been reported. Subsequent analysis determined that
the MLG OST is unable to withstand the loads generated during a hard
landing event. A MLG OST fracture cannot be detected during routine
maintenance and if not corrected, a fractured MLG OST can lead to
aeroplane structural damage and/or collapse of the MLG.

This [Canadian] AD mandates the replacement of the existing MLG
OSTs with a re-designed part, and the implementation of a new
airworthiness limitation task.

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-
0634.

Related Service Information Under 1 CFR Part 51

Bombardier has issued Service Bulletin SB 670BA-32-058, dated
September 26, 2016. The service information describes procedures for
replacing each MLG OST.

Bombardier has also issued Temporary Revision ALI-0593, dated
December 18, 2017. The service information describes new life limits
for the MLG OSTs.

These service information are 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

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 the relevant information and determined the unsafe
condition described previously is likely to exist or develop on other
products of the same type design.

This AD requires revisions to certain operator maintenance
documents to include new actions (e.g., inspections). Compliance with
these actions is required by 14 CFR 91.403(c). For airplanes that have
been previously modified, altered, or repaired in the areas addressed
by this proposed AD, the operator may not be able to accomplish the
actions described in the revisions. In this situation, to comply with
14 CFR 91.403(c), the operator must request approval for an alternative
method of compliance according to paragraph (i) of this proposed AD.
The request should include a description of changes to the required
actions that will ensure the continued damage tolerance of the affected
structure.

Proposed AD Requirements

This proposed AD would require replacing the MLG OST and revising
the maintenance or inspection program, as applicable, to incorporate
new or more restrictive maintenance requirements and airworthiness
limitations.

Costs of Compliance

We estimate that this proposed AD affects 542 airplanes of U.S.
registry. We estimate the following costs to comply with this proposed
AD:

Estimated Costs

Action Labor cost Parts cost Cost per product Cost on U.S. operators
Replacement (left- and right-hand sides) 24 work-hours x $85 per hour = $2,040 * $0 $2,040 $1,105,680

* We have received no definitive data that would enable us to provide cost
estimates for the parts cost in this AD.

We have determined that revising the maintenance or inspection
program takes an average of 90 work-hours per operator, although we
recognize that this number may vary from operator to operator. In the
past, we have estimated that this action takes 1 work-hour per airplane.
Since operators incorporate maintenance or inspection program changes for
their affected fleet(s), we have determined that a per-operator estimate
is more accurate than a per-airplane estimate. Therefore, we estimate the
total cost per operator to be $7,650 (90 work-hours x $85 per work-hour).

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 proposed 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 adding the following new airworthiness
directive (AD):