preamble attached >>>
ADs updated daily at www.Tdata.com
2020-11-13 DE HAVILLAND AIRCRAFT OF CANADA LIMITED (TYPE CERTIFICATE PREVIOUSLY HELD BY BOMBARDIER, INC.):
Amendment 39-19917; Docket No. FAA-2020-0099; Product Identifier 2019-NM-169-AD.

(a) EFFECTIVE DATE

    This AD is effective July 14, 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
    instructions. For  airplanes having  serial numbers  4001 through 4304
    inclusive, 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 re-
    quired 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
     specified in  paragraph (g)  of this  AD, do  the action specified in
     paragraph (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
    replaced  in  accordance  with  paragraph   (3)  of  Part  A  of   the
    Accomplishment Instructions of  Bombardier Service Bulletin  84-54-14,
    Revision J, dated September  17, 2010; or paragraph  (2) of Part A  of
    the Accomplishment 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 intervals  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
    replacement 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
    specified 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  accomplished 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   Aircraft  of   Canada  Limited'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  AD   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) Service information identified in this AD  that is not incorporated by
    reference is available at the addresses specified in paragraphs (s)(3)
    and (4) of this AD.

(s) MATERIAL INCORPORATED BY REFERENCE

(1) The Director of the Federal Register  approved  the  incorporation  by
    reference (IBR) of  the service information  listed in this  paragraph
    under 5 U.S.C. 552(a) and 1 CFR part 51.

(2) You must use this service information as applicable  to do the actions
    required by this AD, unless this AD specifies otherwise.

(i) Bombardier Service Bulletin 84-54-14, Revision K, dated August 7, 2018

(ii) Bombardier Service Bulletin 84-54-16 Revision D, dated August 7, 2018

(iii) Bombardier Modification  Summary  Package  IS4Q5400012,  Revision B,
      dated July 11, 2012.

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

(4) You may view  this  service  information  at  the  FAA,  Airworthiness
    Products Section, Operational Safety Branch, 2200 South 216th St., Des
    Moines, WA.  For  information  on the availability of this material at
    the FAA, call 206-231-3195.

(5) You  may  view  this  service  information  that  is  incorporated  by
    reference at the National Archives and Records Administration  (NARA).
    For information on the availability of this material  at  NARA,  email
    fedreg.legal@nara.gov,  or  go  to:  https://www.archives.gov/federal-
    register/cfr/ibr-locations.html.

Issued on May 29, 2020. Lance T Gant, Director, Compliance & Airworthiness
Division, Aircraft Certification Service.

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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0099; Product Identifier 2019-NM-169-AD; Amendment
39-19917; AD 2020-11-13]
RIN 2120-AA64

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

AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).

ACTION: Final rule.

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

SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2010-23-
04, which applied to all De Havilland Aircraft of Canada Limited Model
DHC-8-400 series airplanes. AD 2010-23-04 required repetitive detailed
inspections of the nacelle attachment fittings for cracks, a
conductivity inspection of the nacelle attachment fittings, and
replacement if necessary. This AD continues to require these
inspections and replacement if necessary, removes a certain inspection
requirement for certain airplanes, and adds a new requirement to
replace the rear spar fitting and nacelle attaching structure with a
new nacelle attachment fitting. This AD was prompted by a determination
that it is necessary to do a replacement with new nacelle attachment
fittings. The FAA is issuing this AD to address the unsafe condition on
these products.

DATES: This AD is effective July 14, 2020.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of July 14, 2020.

ADDRESSES: For service information identified in this final rule,
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 referenced service
information at the FAA, Airworthiness Products Section, Operational
Safety Branch, 2200 South 216th St., Des Moines, WA. For information on
the availability of this material at the FAA, call 206-231-3195. It is
also available on the internet at https://www.regulations.gov by
searching for and locating Docket No. FAA-2020-0099.

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 final rule, any comments received, and other information. The
address for Docket Operations is 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: 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:

Discussion

Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian AD CF-2010-30R2, dated July
30, 2019, (also referred to as the Mandatory Continuing Airworthiness
Information, or ``the MCAI''), to correct an unsafe condition for all
De Havilland Aircraft of Canada Limited (Type Certificate previously
held by Bombardier, Inc.) Model DHC-8-400, -401, and -402 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.
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 to supersede AD 2010-23-04, Amendment 39-16493 (75 FR
68174, November 5, 2010) (``AD 2010-23-04''). AD 2010-23-04 applied to
all De Havilland Aircraft of Canada Limited Model DHC-8-400 series
airplanes. The NPRM published in the Federal Register on March 12, 2020
(85 FR 14423). The NPRM was prompted by reports of cracked nacelle
attachment fittings, which a preliminary investigation determined to be
caused by stress corrosion, and a determination that it is necessary to
install new nacelle attachment fittings in order to address the unsafe
condition. The NPRM proposed to continue to require repetitive detailed
inspections of the nacelle attachment fittings for cracks, a
conductivity inspection of the nacelle attachment fittings, and
replacement if necessary. The NPRM also proposed to 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 issuing this AD to address
reports of cracked nacelle attachment fittings, 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.
See the MCAI for additional background information.

Comments

The FAA gave the public the opportunity to participate in
developing this final rule. The FAA received no comments on the NPRM or
on the determination of the cost to the public.

Conclusion

The FAA reviewed the relevant data and determined that air safety
and the public interest require adopting this final rule as proposed,
except for minor editorial changes. The FAA has determined that these
minor changes:
Are consistent with the intent that was proposed in the
NPRM for addressing the unsafe condition; and
Do not add any additional burden upon the public than was
already proposed in the NPRM.

Related Service Information Under 1 CFR Part 51

Bombardier, Inc. 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, Inc. 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; and 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, Inc. 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.

Costs of Compliance

The FAA estimates that this AD affects 54 airplanes of U.S.
registry.
The FAA estimates the following costs to comply with this 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 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 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) 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.

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