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PROPOSED AD DE HAVILLAND AIRCRAFT OF CANADA LIMITED (TYPE CERTIFICATE PREVIOUSLY HELD BY BOMBARDIER, INC.): Docket No. FAA-2020-0099; Product Identifier 2019-NM-169-AD.
(a) COMMENTS DUE DATE

    The FAA must receive comments by April 27, 2020.

(b) AFFECTED ADS

    This  AD  replaces  AD  2010-23-04,  Amendment 39-16493  (75 FR 68174,
    November 5, 2010) ("AD 2010-23-04").

(c) APPLICABILITY

    This  AD  applies  to  De Havilland Aircraft of Canada  Limited  (Type
    Certificate Previously Held by Bombardier, Inc.) Model DHC-8-400, -401
    and -402 airplanes, certificated in any category,  serial numbers 4001
    and subsequent.

(d) SUBJECT

    Air Transport Association (ATA) of America Code 54, Nacelles/pylons.

(e) REASON

    This AD was prompted by reports of cracked nacelle attachment fittings
    which a preliminary  investigation determined to  be caused by  stress
    corrosion.  The FAA  is  issuing  this AD  to address  this condition,
    which, if not detected and corrected, could compromise the  structural
    integrity of  the nacelle  attachment fitting  and possibly  result in
    collapse of the landing gear.

(f) COMPLIANCE

    Comply with this AD within the compliance times specified,  unless al-
    ready done.

(g) RETAINED DETAILED AND CONDUCTIVITY INSPECTIONS  AND REPLACEMENT,  WITH
    REVISED SERVICE INFORMATION AND REVISED REPLACEMENT INSTRUCTIONS

    This paragraph restates  the requirements of paragraph (g) of AD 2010-
    23-04,  with revised service information  and  revised replacement in-
    structions.  For airplanes having serial numbers 4001 through 4304 in-
    clusive, 4314, and 4315:  Within 100 flight hours  after  November 22,
    2010  (the effective date of AD 2010-23-04),  do a detailed inspection
    for  cracking,  and a conductivity inspection on each of the 4 nacelle
    attachment fittings in accordance with the Accomplishment Instructions
    of Bombardier Service Bulletin 84-54-14,  Revision K,  dated August 7,
    2018.  Repeat the detailed inspection  at intervals  not to exceed 300
    flight  hours,  except  as  provided  by  paragraph (i)  of  this  AD.
    Accomplishing the replacement specified in paragraph (g)(1)(ii) or (g)
    (2)(ii)(B) of this AD terminates  the  inspections  required  by  this
    paragraph.

(1) If any nacelle attachment fitting  is  found cracked,  before  further
    flight, do the action specified in paragraph (g)(1)(i) or (ii) of this
    AD. As of the effective date of this AD,  only the action specified in
    paragraph (g)(1)(ii) of this AD may be done.

(i) Replace the fitting  with a new fitting  in accordance  with paragraph
    (2) of Part A of the Accomplishment Instructions of Bombardier Service
    Bulletin 84-54-14, Revision K, dated August 7, 2018.

(ii) Replace  the  rear  spar  nacelle  attachment fitting  and associated
     structure with a  new nacelle attachment  fitting, part number  (P/N)
     8Z9305, and  do all  applicable related  investigative and corrective
     actions, in accordance with Part B of the Accomplishment Instructions
     of Bombardier Service Bulletin  84-54-16 Revision D,  dated August 7,
     2018.  Do all applicable related investigative and corrective actions
     before further flight.

(2) If the conductivity of any test points  on any fitting is found  to be
    greater  than  45.0  percent  International  Annealed  Copper Standard
    (IACS) or if  the conductivity of  any test points  on any fitting  is
    found to be less  than 38.0 percent IACS,  do the actions required  by
    paragraphs (g)(2)(i) and (ii) of this AD.

(i) Within 24 hours after accomplishing the conductivity inspection speci-
    fied in  paragraph (g)  of this  AD, do  a detailed  inspection of the
    nacelle  attachment  fitting  for  cracking,  in  accordance  with the
    Accomplishment Instructions of  Bombardier Service Bulletin  84-54-14,
    Revision K,  dated August 7, 2018, and repeat thereafter at  intervals
    not to exceed 24 hours.  If cracking is found, before  further flight,
    replace  the  fitting  with  a  new  fitting  in  accordance  with the
    requirements of paragraph  (g)(2)(ii) of this  AD. Replacement of  the
    fitting terminates the daily detailed inspection requirements of  this
    paragraph.

(ii) Except as required  by paragraph (g)(2)(i)  of  this  AD:  Within 300
     flight hours  after accomplishing  the conductivity inspection speci-
     fied in paragraph (g)  of this AD,  do the action specified  in para-
     graph (g)(2)(ii)(A)  or  (B) of this AD.  As of the effective date of
     this AD, only the action specified in paragraph (g)(2)(ii)(B) of this
     AD may be done.

(A) Replace the fitting  with a new fitting  in accordance  with paragraph
    (2) of Part A of the Accomplishment Instructions of Bombardier Service
    Bulletin 84-54-14, Revision K, dated August 7, 2018.

(B) Replace  the  rear  spar  nacelle  attachment  fitting  and associated
    structure  with a new nacelle attachment fitting,  P/N 8Z9305,  and do
    all  applicable  related  investigative  and  corrective  actions,  in
    accordance   with  Part  B   of  the  Accomplishment  Instructions  of
    Bombardier Service Bulletin 84-54-16 Revision D, dated August 7, 2018.
    Do all applicable related investigative  and corrective actions before
    further flight.

(h) RETAINED INSPECTIONS AND REPLACEMENT WITH REVISED SERVICE INFORMATION,
    REVISED AFFECTED AIRPLANES, AND REVISED REPLACEMENT INSTRUCTIONS

    This paragraph restates the requirements of paragraph (i)  of AD 2010-
    23-04,  with revised service information,  revised affected airplanes,
    and  revised  replacement instructions.  For  airplanes having  serial
    numbers 4305 through 4313 inclusive, and 4316 through 4380  inclusive,
    and airplanes  that have  replaced nacelle  attachment fitting(s) with
    P/N 854146663: Within 1,200 flight hours after November 22, 2010  (the
    effective  date  of  AD  2010-23-04),  do  a  detailed  inspection for
    cracking on each of the  4 nacelle attachment fittings, in  accordance
    with the  Accomplishment Instructions  of Bombardier  Service Bulletin
    84-54-14, Revision K, dated August 7, 2018. If any nacelle  attachment
    fitting  is  found  cracked,  before  further  flight,  do  the action
    specified in paragraph (h)(1) or (2)  of this AD. As of the  effective
    date of this AD, only the action specified in paragraph (h)(2) of this
    AD  may  be  done.  Thereafter,  repeat  the  detailed  inspection  at
    intervals  not  to exceed  300  flight hours,  except  as provided  by
    paragraph (i) of this  AD. Accomplishing the replacement  specified in
    paragraph (h)(2)  of this  AD terminates  the inspections  required by
    this paragraph.

(1) Replace the fitting with a new fitting  in  accordance  with paragraph
    (2) of Part A of the Accomplishment Instructions of Bombardier Service
    Bulletin 84-54-14, Revision K, dated August 7, 2018.

(2) Replace  the  rear  spar  nacelle  attachment  fitting  and associated
    structure with a new nacelle attachment fitting,  P/N 8Z9305,  and  do
    all  applicable  related  investigative  and  corrective  actions,  in
    accordance   with  Part  B   of  the  Accomplishment  Instructions  of
    Bombardier Service Bulletin 84-54-16 Revision D, dated August 7, 2018.
    Do all applicable related investigative  and corrective actions before
    further flight.

(i) RETAINED INSPECTION COMPLIANCE TIME, WITH REVISED SERVICE INFORMATION

    This paragraph restates the requirements of paragraph (j)  of AD 2010-
    23-04,  with revised service information.  For any fitting that is re-
    placed in accordance  with paragraph (3) of Part A  of the Accomplish-
    ment Instructions of Bombardier Service Bulletin 84-54-14, Revision J,
    dated September 17, 2010 or paragraph (2) of Part A of the Accomplish-
    ment Instructions of Bombardier Service Bulletin 84-54-14, Revision K,
    dated August 7, 2018, as specified in paragraph (g) or (h) of this AD:
    Within 1,200 flight hours  after replacing the fitting,  do a detailed
    inspection of that replaced fitting  as specified  in paragraph (g) or
    (h) of this AD,  and repeat the detailed inspection  thereafter at in-
    tervals not to exceed 300 flight hours.  Accomplishing the replacement
    specified in paragraph (g)(1)(ii), (g)(2)(ii)(B), or (h)(2) of this AD
    terminates the inspections required by this paragraph.

(j) RETAINED CREDIT FOR PREVIOUS ACTIONS (REPLACING THE FITTING), WITH RE-
    VISED PARAGRAPH REFERENCES

    This paragraph restates the credit provided  in  paragraph (k)  of  AD
    2010-23-04,  with revised paragraph references.  Accomplishing the re-
    placement of the nacelle fittings  in accordance  with any  Bombardier
    service bulletin  identified  in figure 1 to paragraphs (j) and (k) of
    this AD before November 22, 2010 (the effective date of AD 2010-23-04)
    is also acceptable for compliance with the fitting replacements speci-
    fied in paragraphs (g)(1)(i), (g)(2)(ii)(A), and (h)(1) of this AD.

     FIGURE 1 TO PARAGRAPHS (J) AND (K)  ACCEPTABLE SERVICE INFORMATION  
    ______________________________________________________________________
    BOMBARDIER SERVICE BULLETIN       REVISION              DATED
    ______________________________________________________________________
              84-54-14                Original          April 16, 2010
              84-54-14                   A              April 22, 2010
              84-54-14                   B              June 11, 2010
              84-54-14                   C              June 30, 2010
              84-54-14                   D              July 5, 2010
              84-54-14                   E              August 19, 2010
              84-54-14                   F              August 20, 2010
              84-54-14                   G              September 9, 2010
              84-54-14                   H              September 10, 2010
    ______________________________________________________________________

(k) RETAINED CREDIT FOR PREVIOUS ACTIONS (INSPECTIONS), WITH NO CHANGES

    This paragraph restates  the credit provided  in paragraph (l)  of  AD
    2010-23-04 with no changes. Accomplishment of the inspections required
    by paragraphs (g) and (h)  of  this  AD  before November 22, 2010 (the
    effective date of AD 2010-23-04)  in accordance  with  any  Bombardier
    service bulletin identified  in figure 1  to paragraphs (j) and (k) of
    this AD is acceptable  for  compliance  with the corresponding actions
    required by paragraphs (g) and (h) of this AD.

(l) NEW REQUIREMENTS OF THIS AD: MODIFICATION OF THE REAR SPAR FITTING AND
    NACELLE ATTACHING STRUCTURE

    For airplanes with nacelle attachment fitting P/N 85414663: Unless al-
    ready done  as specified  in paragraph  (g)(1)(ii), (g)(2)(ii)(B),  or
    (h)(2) of this AD: Within  8,000 flight hours or 48  months, whichever
    occurs first,  from the  effective date  of this  AD, replace the rear
    spar nacelle attachment  fitting and associated  structure with a  new
    nacelle attachment fitting, P/N 8Z9305, and do all applicable  related
    investigative and corrective actions, in accordance with Part B of the
    Accomplishment Instructions of  Bombardier Service Bulletin  84-54-16,
    Revision  D,  dated  August   7,  2018.  Do  all   applicable  related
    investigative and corrective actions before further flight.

(m) NEW CREDIT FOR PREVIOUS ACTIONS

(1) This paragraph provides credit for actions required  by paragraphs (g)
    and (h) of this AD that are identified  in Bombardier Service Bulletin
    84-54-14, Revision K,  dated August 7, 2018,  if  those  actions  were
    performed  before  the  effective date  of  this  AD using  Bombardier
    Service Bulletin 84-54-14, Revision J, dated September 17, 2010, which
    was incorporated by reference in AD 2010-23-04;  except as provided by
    paragraph (p) of this AD.

(2) This paragraph provides credit  for accomplishing  the  replacement of
    the  rear spar  fitting and  nacelle attaching  structure required  by
    paragraph (l) of this AD,  if those actions were performed  before the
    effective date of this AD  using the service information specified  in
    paragraphs (m)(2)(i) through (iii) of this AD.

(i) Bombardier Service Bulletin 84-54-16, dated April 29, 2011.

(ii) Bombardier Service Bulletin 84-54-16,  Revision  A,  dated  August 1,
     2011.

(iii) Bombardier Service Bulletin 84-54-16, Revision C,  dated January 31,
      2017.

(3) This paragraph provides credit  for  accomplishing  the replacement of
    the rear spar fitting and  nacelle  attaching  structure  required  by
    paragraph (l) of this AD,  if those actions were performed  before the
    effective date of this AD  using Bombardier Service Bulletin 84-54-16,
    Revision B dated October 6, 2016. Although Bombardier Service Bulletin
    84-54-16, Revision B, dated October 6, 2016,  incorrectly stated  that
    airworthiness  limitations  (AWLs)  or  damage  tolerance  inspections
    (DTIs) are not  affected, they are  affected. Refer to  the applicable
    AWLs   for   Post/Pre-Modification  Summary   (ModSum)   4-113697  and
    Bombardier  Service  Bulletin  84-54-16  in  the  existing maintenance
    requirements manual.

(4) This paragraph provides credit for accomplishing the action identified
    in Bombardier Service Bulletin  84-54-14, Revision K, dated  August 7,
    2018, that are required by paragraphs (g) and (h) of this AD, if those
    actions were performed before the effective date of this AD using  the
    service information specified in paragraphs (m)(4)(i) through (iv)  of
    this AD.

(i) Bombardier Service Bulletin 84-54-15, dated August 20, 2010.

(ii) Bombardier Service Bulletin 84-54-15,  Revision A,  dated October 25,
     2010.

(iii) Bombardier Service Bulletin 84-54-15, Revision B,  dated February 2,
      2017.

(iv) Bombardier Service Bulletin 84-54-15,  Revision  C,  dated  August 7,
     2018.

(n) TERMINATING ACTION FOR CERTAIN ACTIONS IN PARAGRAPHS (G), (H), AND (I)
    OF THIS AD

    Accomplishing the modification  of the rear  spar fitting and  nacelle
    attaching structure required  by paragraph (l)  of this AD  terminates
    the repetitive inspection required by paragraphs (g), (h), and (i)  of
    this AD for that airplane.

(o) PARTS INSTALLATION LIMITATIONS

    As of the effective date of this AD, no person may install a rear spar
    nacelle attachment fitting P/N 85414663 on any airplane.

(p) CREDIT FOR ALTERNATIVE TO CERTAIN CREDIT ACTIONS

    For airplanes on which Bombardier Service Bulletin 84 54 14,  Revision
    J, dated  September 17,  2010, was  done before  the effective date of
    this AD:  As an  alternative to  applying sealant  to each fitting and
    access panel  as specified  in paragraph  C.(1) of  the Accomplishment
    Instructions  of  Bombardier Service  Bulletin  84-54-14,  Revision J,
    dated September 17,  2010, the use  of the instructions  of Bombardier
    Modification Summary Package IS4Q5400012,  Revision B,  dated July 11,
    2012, to apply sealant is  also acceptable if accomplished before  the
    effective date of this AD.

(q) OTHER FAA AD PROVISIONS

(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.

(i) Before using any approved AMOC,  notify your appropriate principal in-
    spector, or lacking  a principal inspector,  the manager of  the local
    flight standards district office/certificate holding district office.

(ii) AMOCs approved previously  for AD 2010-23-04,  are approved  as AMOCs
     for the corresponding provisions of this AD.

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

(r) RELATED INFORMATION

(1) Refer   to   Mandatory  Continuing  Airworthiness  Information  (MCAI)
    Canadian Airworthiness Directive  CF-2010-30R2,  dated  July 30, 2019,
    for related  information.  This MCAI may be found  in the AD docket on
    the internet  at  https://www.regulations.gov  by  searching  for  and
    locating Docket No. FAA-2020-0099.

(2) For more information about this AD,  contact Andrea Jimenez, Aerospace
    Engineer, Airframe and Propulsion Section,  FAA,  New York ACO Branch,
    1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-
    7330; fax 516-794-5531; email 9-avs-nyaco-cos@faa.gov.

(3) For service information identified  in this AD,  contact  De Havilland
    Aircraft of Canada Limited, Q-Series Technical Help Desk,  123 Garratt
    Boulevard,  Toronto, Ontario M3K 1Y5, Canada;  telephone 416-375-4000;
    fax  416-375-4539;   email   thd@dehavilland.com;   internet  https://
    dehavilland.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.

Issued on February 12, 2020.  Gaetano A. Sciortino,  Deputy  Director  for
Strategic  Initiatives,  Compliance  &  Airworthiness  Division,  Aircraft
Certification Service.

DATES: The FAA must receive comments on this proposed AD by April 27, 2020
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0099; Product Identifier 2019-NM-169-AD]
RIN 2120-AA64

Airworthiness Directives; De Havilland Aircraft of Canada Limited
(Type Certificate Previously Held by Bombardier, Inc.) Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: The FAA proposes to supersede Airworthiness Directive (AD)
2010-23-04, which applies to all De Havilland Aircraft of Canada
Limited Model DHC-8-400 series airplanes. AD 2010-23-04 requires
repetitive detailed inspections of the nacelle attachment fittings for
cracks, a conductivity inspection of the nacelle attachment fittings,
and replacement if necessary. Since AD 2010-23-04 was issued, the FAA
has determined that it is necessary to do a replacement with new
nacelle attachment fittings. This proposed AD would retain the
requirements of AD 2010-23-04, remove a certain inspection requirement
for certain airplanes, and add a new requirement to replace the rear
spar fitting and nacelle attaching structure with a new nacelle
attachment fitting. The FAA is proposing this AD to address the unsafe
condition on these products.

DATES: The FAA must receive comments on this proposed AD by April 27,
2020.

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 https://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 De
Havilland Aircraft of Canada Limited, Q-Series Technical Help Desk, 123
Garratt Boulevard, Toronto, Ontario M3K 1Y5, Canada; telephone 416-375-
4000; fax 416-375-4539; email thd@dehavilland.com; internet https://
dehavilland.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 https://www.regulations.
gov by searching for and locating Docket No. FAA-2020-0099;
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 is listed above.
Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Andrea Jimenez, Aerospace Engineer,
Airframe and Propulsion Section, FAA, New York ACO Branch, 1600 Stewart
Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7330; fax 516-
794-5531; email 9-avs-nyaco-cos@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites 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-2020-0099;
Product Identifier 2019-NM-169-AD" at the beginning of your comments.
The FAA specifically invite comments on the overall regulatory,
economic, environmental, and energy aspects of this proposed AD. The
FAA will consider all comments received by the closing date and may
amend this proposed AD based on those comments.

The FAA will post all comments received, without change, to https://www.
regulations.gov, including any personal information you provide.
The FAA will also post a report summarizing each substantive verbal
contact received about this proposed AD.

Discussion

The FAA issued AD 2010-23-04, Amendment 39-16493 (75 FR 68174,
November 5, 2010) ("AD 2010-23-04"), for all De Havilland Aircraft of
Canada Limited Model DHC-8-400 series airplanes. AD 2010-23-04 requires
repetitive detailed inspections of the nacelle attachment fittings for
cracks, a conductivity inspection of the nacelle attachment fittings,
and replacement if necessary. AD 2010-23-04 resulted from reports of
cracked nacelle attachment fittings, which a preliminary investigation
determined to be caused by stress corrosion. The FAA issued AD 2010-23-
04 to address this condition, which, if not detected and corrected,
could compromise the structural integrity of the nacelle attachment
fitting and possibly result in collapse of the landing gear.

Actions Since AD 2010-23-04 Was Issued

Since AD 2010-23-04 was issued, the FAA has determined that it is
necessary to require a replacement with new nacelle attachment
fittings, which would be terminating action for the inspections
specified in AD 2010-23-04. Additionally, paragraph (i) of AD 2010-23-
04 requires repetitive detailed inspections for cracking on each of the
four nacelle attachment fittings for airplanes having serial numbers
4305 through 4313 inclusive, and 4316 and subsequent. The FAA has
retained this inspection in paragraph (h) of this proposed AD, but
serial numbers 4381 and subsequent were modified in production and
cannot have the affected part installed, so those airplanes were
removed from the retained actions in paragraph (h) of this proposed AD.

Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian AD CF-2010-30R2, dated July
30, 2019 (referred to after this as the Mandatory Continuing
Airworthiness Information, or "the MCAI"), to correct an unsafe
condition for all De Havilland Aircraft of Canada Limited Model DHC-8-
400 series airplanes. You may examine the MCAI in the AD docket on the
internet at https://www.regulations.gov by searching for and locating
Docket No. FAA-2020-0099.

This proposed AD was prompted by a determination that it is
necessary to install new nacelle attachment fitting in order to address
the unsafe condition. The FAA is proposing this AD to address cracked
nacelle attachment fittings, which a preliminary investigation
determined to be caused by stress corrosion. This condition, if not
detected and corrected, could compromise the structural integrity of
the nacelle attachment fitting and possibly result in collapse of the
landing gear. See the MCAI for additional background information.

Related Service Information Under 1 CFR Part 51

Bombardier has issued Service Bulletin 84-54-14, Revision K, dated
August 7, 2018. This service bulletin describes procedures for a
conductivity inspection of the nacelle attachment fittings, repetitive
detailed inspections of the nacelle attachment fittings for cracks, and
replacement of the fitting.

Bombardier has also issued Service Bulletin 84-54-16, Revision D,
dated August 7, 2018. This service information describes procedures for
replacing the rear spar nacelle attachment fitting and associated
structure with a new nacelle attachment fitting, part number (P/N)
8Z9305. The replacement includes applicable related investigative and
corrective actions. The related investigative actions include an
inspection of the internal bore and external surface of the main
landing gear yoke pins, the drag strut pins, and the stabilizer brace
pins for signs of corrosion and damage; an inspection of the inner bore
and outer surface of the coat hangar pins for signs of corrosion and
damage. The corrective actions include repair, rework, or replacement.

Bombardier has also issued Modification Summary Package
IS4Q5400012, Revision B, dated July 11, 2012. This service information
describes procedures for applying a fay sealant gasket to the rear spar
access fitting access panel.

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

This product has been approved by the aviation authority of another
country, and is approved for operation in the United States. Pursuant
to a bilateral agreement with the State of Design Authority, the FAA
has been notified of the unsafe condition described in the MCAI and
service information referenced above. The FAA is proposing this AD
because the agency 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.

Proposed Requirements of This NPRM

This proposed AD would retain all of the requirements of AD 2010-
23-04. This proposed AD would also require accomplishing the actions
specified in the service information described previously.

Costs of Compliance

The FAA estimates that this proposed AD affects 54 airplanes of
U.S. registry.

The FAA estimates the following costs to comply with this proposed
AD:

Estimated Costs for Required Actions *

Action
Labor cost
Parts cost
Cost per product
Cost on U.S. operators
Retained actions from AD 2010-23-04 3 work-hours x $85 per hour = $255 $0 $255 $13,770
New proposed actions 320 work-hours x $85 per hour = $27,200 Up to $104,739 Up to $131,939 Up to $7,124,706

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.

The FAA is 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

The FAA has 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) Will not affect intrastate aviation in Alaska, and

(3) 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)
2010-23-04, Amendment 39-16493 (75 FR 68174, November 5, 2010), and
adding the following new AD: