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2021-19-12 MHI RJ AVIATION ULC (TYPE CERTIFICATE PREVIOUSLY HELD BY BOMBARDIER, INC.): Amendment 39-21730; Docket No. FAA-2021-0309; Project Identifier MCAI-2020-00918-T.
(a) EFFECTIVE DATE

    This airworthiness directive (AD) is effective November 10, 2021.

(b) AFFECTED ADS

    None.

(c) APPLICABILITY

    This AD applies to the MHI RJ Aviation ULC (type certificate previous-
    ly held by Bombardier, Inc.) airplanes,  certificated in any category,
    specified in paragraphs (c)(1) through (3) of this AD.

(1) Model CL-600-2C10  (Regional Jet Series 700, 701 & 702)  and Model CL-
    600-2C11 (Regional Jet Series 550) airplanes, serial numbers 10002 and
    subsequent.

(2) Model CL-600-2D15 (Regional Jet Series 705)  airplanes and CL-600-2D24
    (Regional Jet Series 900)  airplanes,  serial numbers 15001 and subse-
    quent.

(3) Model CL-600-2E25 (Regional Jet Series 1000) airplanes, serial numbers
    19001 and subsequent.

(d) SUBJECT

    Air Transport Association (ATA) of America Code 32, Landing Gear.

(e) REASON

    This AD was  prompted by reports  and a design  review indicating that
    there could be corrosion on the main landing gear (MLG) outer cylinder
    assemblies at  the interface  with the  gland nut  on the  shock strut
    installation  and on  the forward  and aft  trunnion pins  in the  MLG
    dressed shock strut  assemblies; primer was  not correctly applied  at
    the gland nut  thread relief groove  and chamfer areas  on certain MLG
    outer cylinders during  production; and corrosion-inhibiting  compound
    (CIC) could have inadvertently  been removed from certain  MLG forward
    and  aft   trunnion  pins   and  grease   adapter  assemblies   during
    maintenance.  The  FAA  is  issuing  this  AD  to  address  undetected
    corrosion on the MLG forward and aft trunnion pins, and the gland  nut
    interface on certain MLG outer cylinders, which could result in an MLG
    collapse.

(f) COMPLIANCE

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

(g) INSPECTION AND APPLICATION OF CORROSION PROTECTION  FOR MLG OUTER CYL-
    INDER ASSEMBLIES AND CERTAIN MLG DRESSED SHOCK STRUT ASSEMBLIES

    For airplanes identified in paragraphs (c)(1) and (2)  of this AD with
    MLG outer cylinder assemblies  and  MLG dressed shock strut assemblies
    having part numbers  and  serial numbers  specified in the effectivity
    tables in Section 1.A.(1) of Bombardier Service Bulletin 670BA-32-024,
    Revision C, dated February 11, 2015 (Bombardier Service Bulletin 670BA
    -32-024, Revision C):  At  the  applicable time specified in paragraph
    (g)(1) or (2)  of  this  AD,  do  a  detailed  visual  inspection  for
    corrosion, and all other required actions specified in, and in accord-
    ance with, Section 2.,  Part A,  of the Accomplishment Instructions of
    Bombardier Service Bulletin 670BA-32-024, Revision C.

(1) For MLG assemblies  that have accumulated 12,500 total flight hours or
    less, and have been in service  for 72 months or less from  entry into
    service or  the last  overhaul date:  Within 6,500  flight hours or 36
    months, whichever comes first, after the effective date of this AD.

(2) For MLG assemblies that have accumulated more than 12,500 total flight
    hours, or have been in service for more than 72 months from entry into
    service or  the last  overhaul date:  Within 3,500  flight hours or 24
    months, whichever occurs first, after the effective date of this AD.

(h) INSPECTION OF CERTAIN OTHER MLG DRESSED SHOCK STRUT ASSEMBLIES AND COR
    -RECTIVE ACTION

    For airplanes  identified in  paragraphs (c)(1)  and (2)  of this  AD,
    equipped with MLG dressed  shock strut assemblies having  part numbers
    (P/Ns) 49000-25 through 49000-46  and P/Ns 49050-15 through  49050-22,
    on which the MLG active dynamic seal has been replaced with the  spare
    dynamic seal as  specified in Bombardier  CRJ700/705/900/1000 Aircraft
    Maintenance Manual (AMM), CSP B-001,  Task 32-11-10-960-802,  Revision
    37, dated November 25, 2011, or earlier: At the applicable time speci-
    fied in paragraph (h)(1) or (2) of this AD,  do a detailed  visual in-
    spection of the MLG dressed shock strut assemblies for corrosion,  and
    all applicable corrective actions, in accordance with Section 2., Part
    B, of the Accomplishment Instructions  of Bombardier  Service Bulletin
    670BA-32-024, Revision C.

(1) For MLG assemblies  that have accumulated 12,500 total flight hours or
    less, and have been in service  for 72 months or less from  entry into
    service or  the last  overhaul date:  Within 6,500  flight hours or 36
    months, whichever comes first, after the effective date of this AD.

(2) For MLG assemblies that have accumulated more than 12,500 total flight
    hours, or have been in service for more than 72 months from entry into
    service or  the last  overhaul date:  Within 3,500  flight hours or 24
    months, whichever occurs first, after the effective date of this AD.

(i) INSPECTION OF MLG OUTER CYLINDER AT THE GLAND NUT THREADS,  THREAD RE-
    LIEF GROOVE, AND CHAMFER AND CORRECTIVE ACTION

    For airplanes identified in paragraphs  (c)(1) through (3) of this  AD
    equipped with MLG  outer cylinder assemblies  having part numbers  and
    serial numbers specified in  Section 1.A., Effectivity, of  Bombardier
    Service Bulletin  670BA-32-052,  dated  February 9, 2015: Within 6,500
    flight hours or 36 months, whichever occurs first after the  effective
    date of  this AD,  do a  detailed visual  inspection of  the MLG shock
    strut outer  cylinder assemblies,  and do  all other  required actions
    specified in, and in accordance with, Section 2. of the Accomplishment
    Instructions  of  Bombardier  Service  Bulletin  670BA-32-052,   dated
    February 9, 2015.

(j) INSPECTION OF CERTAIN MLG FORWARD AND AFT TRUNNION PINS AND CORRECTIVE
    ACTION

    For airplanes identified in paragraphs  (c)(1) through (3) of this  AD
    equipped with  MLG forward  and aft  trunnion pins  and grease adapter
    assemblies having part numbers and serial numbers specified in Section
    1.A.,  Effectivity,  of  Bombardier  Service  Bulletin   670BA-32-034,
    Revision  B,  dated  December 21,  2018  (Bombardier  Service Bulletin
    670BA-32-034,  Revision  B):  At  the  applicable  time  specified  in
    paragraph (j)(1) or (2) of this AD, do a detailed visual inspection of
    the MLG forward and aft trunnion pins and do all applicable corrective
    actions, in accordance  with Section 2.B.  and paragraphs 2.C.(6)  and
    (8) of the Accomplishment Instructions of Bombardier Service  Bulletin
    670BA-32-034, Revision B.

Note 1 to the introductory text of paragraph (j): The corrective action is
applicable only to MLG forward and aft trunnion pins having  P/Ns 49101-9,
-11, and -13 reworked  from P/Ns 49101-1, -5, and -7,  as specified in the
procedures  in Goodrich Service Bulletin 49101-32-47,  any  revision.  The
corrective action is not applicable to MLG forward  and  aft trunnion pins
having P/Ns 49101-9, -11 and -13 that were installed as original equipment
or purchased from Goodrich Landing Gear.

(1) For  MLG forward and aft trunnion pins  and  grease adapter assemblies
    that have not had the procedures  specified in Goodrich Service Bulle-
    tin 49101-32-47,  any revision,  incorporated,  at the applicable time
    specified in paragraph (j)(1)(i) or (ii) of this AD.

(i) For MLG forward  and aft trunnion pins  that  have  accumulated 10,000
    total flight hours or less, and have been in service 60 months or less
    from the entry into service or last overhaul date: Within 6,500 flight
    hours or 36 months, whichever  occurs first, after the effective  date
    of this AD.

(ii) For MLG forward and aft trunnion pins that have accumulated more than
     10,000 total flight hours,  or  have been in service for more than 60
     months from entry  into service or  last overhaul date:  Within 3,000
     flight  hours  or  24  months,  whichever  occurs  first,  after  the
     effective date of this AD.

(2) For MLG forward and aft trunnion pins  that  have  had  the procedures
    specified  in  Goodrich Service  Bulletin  49101-32-47, any  revision,
    incorporated: Within 6,500 flight hours or 36 months, whichever occurs
    first, after the effective date of this AD.

(k) INSPECTION OF CERTAIN OTHER  MLG TRUNNION  PINS  HAVING  P/NS 49101-9,
    49101-11, AND 49101-13,  MAINTAINED USING CERTAIN MAINTENANCE INSTRUC-
    TIONS

    For airplanes identified in paragraphs  (c)(1) through (3) of this  AD
    equipped with MLG forward and  aft trunnion pins having P/Ns  49101-9,
    49101-11, and  49101-13 that  were maintained  in accordance  with the
    tasks identified in paragraphs (k)(1)  through (4) of this AD:  Within
    6,500 flight hours or 36 months  after the effective date of this  AD,
    whichever occurs  first, do  a detailed  visual inspection  of the MLG
    forward  and  aft  trunnion pins,  and  do  all applicable  corrective
    actions,  in  accordance  with   Section  2.  of  the   Accomplishment
    Instructions  of  Bombardier  Service  Bulletin  670BA-32-039,   dated
    February 29, 2012.

Note 2 to the introductory text of paragraph (k):  The  corrective  action
described  in this  paragraph is  not applicable  to MLG  forward and  aft
trunnion pins having P/Ns 49101-9,  -11, and -13 reworked from  P/Ns 49101
-1, -5, and -7 as specified in the procedures in Goodrich SB  49101-32-47,
any  revision.  The  corrective  action  described  in  this  paragraph is
applicable to MLG forward and aft trunnion pins having P/Ns 49101-9,  -11,
and -13 installed as original equipment or purchased from Goodrich Landing
Gear.

(1) Bombardier CRJ700/705/900/1000 AMM,  CSP B-001,  Task 32-11-05-400-801
    A01, Revision 31, dated March 20, 2010, or earlier.

(2) Bombardier CRJ700/705/900/1000 AMM,  CSP B-001,  Task 32-11-05-400-801
    A02, Revision 34, dated November 20, 2010, or earlier.

(3) Bombardier CRJ700/705/900/1000 AMM,  CSP B-001,  Task 32-11-05-400-804
    A01, Revision 35, dated March 20, 2011, or earlier.

(4) Bombardier CRJ700/705/900/1000 AMM,  CSP B-001,  Task 32-11-05-400-805
    A01, Revision 35, dated March 20, 2011, or earlier.

(l) CREDIT FOR PREVIOUS ACTIONS

(1) This paragraph provides credit  for actions required  by paragraph (g)
    of this AD,  if those actions were performed before the effective date
    of this AD using Section 2., Part A of the Accomplishment Instructions
    of Bombardier Service Bulletin 670BA-32-024 Revision B, dated December
    19, 2012.

(2) This paragraph provides credit  for actions required  by paragraph (h)
    of this AD  if those actions were performed  before the effective date
    of this AD using Section 2.,  Part  B,  of the Accomplishment Instruc-
    tions of Bombardier Service Bulletin 670BA-32-024,  Revision B,  dated
    December 19, 2012;  or Bombardier CRJ700/705/900/1000 AMM,  CSP B-001,
    Task 32-11-10-960-802, Revision 38, dated March 25, 2012.

(3) This paragraph provides credit  for actions required  by paragraph (j)
    of this AD  if those actions were performed  before the effective date
    of this AD using Section 2.B.  and  paragraphs 2.C.(6) and (8)  of the
    Accomplishment Instructions  of Bombardier  Service Bulletin 670BA-32-
    034, dated February 29, 2012; or Revision A, dated August 17, 2012.

(4) This paragraph provides credit  for actions required  by paragraph (k)
    of this AD,  if those actions were performed before the effective date
    of this AD using the service information  specified  in paragraphs (l)
    (4)(i) through (iv) of this AD.

(i) Bombardier CRJ700/900/1000 AMM, CSP B-001,  Task 32-11-05-400-801 A01,
    Revision 38, dated March 25, 2012.

(ii) Bombardier CRJ700/900/1000 AMM, CSP B-001, Task 32-11-05-400-801 A02,
     Revision 38, dated March 25, 2012.

(iii) Bombardier CRJ700/900/1000 AMM, CSP B-001, Task 32-11-05-400-804 A01
      Revision 37, dated November 25, 2011,  for actions specified in Sec-
      tion 2.B.(1)  of the Accomplishment Instructions of Bombardier Serv-
      ice Bulletin 670BA-32-039, dated February 29, 2012.

(iv) Bombardier CRJ700/900/1000 AMM, CSP B-001, Task 32-11-05-400-805 A01,
     Revision 37 dated November 25, 2011, for actions specified in Section
     2.B.(2)  of  the  Accomplishment Instructions  of  Bombardier Service
     Bulletin 670BA-32-039, dated February 29, 2012.

(m) NO REQUIREMENT FOR RETURN OF PARTS

    Although certain service information referenced  in this  AD specifies
    to return damaged MLG trunnion pins to Goodrich Landing Gear,  this AD
    does not include that requirement.

(n) 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
    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 MHI  RJ
    Aviation ULC's TCCA Design Approval Organization (DAO). If approved by
    the DAO, the approval must include the DAO-authorized signature.

(o) RELATED INFORMATION

(1) Refer to Mandatory Continuing Airworthiness Information (MCAI) TCCA AD
    CF-2019-17R1, dated June 18, 2020, 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-2021
    - 0309.

(2) For more information about this AD contact: Darren Gassetto, Aerospace
    Engineer, Mechanical Systems and Administrative Services Section, FAA,
    New York  ACO Branch,  1600 Stewart Avenue,  Suite  410,  Westbury, NY
    11590; telephone 516-228-7323; fax 516-794-5531; email 9-avs-nyaco-cos
    @faa.gov.

(p) 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 670BA-32-024,  Revision C,  dated February
    11, 2015.

(ii) Bombardier Service Bulletin 670BA-32-034,  Revision B, dated December
     21, 2018.

(iii) Bombardier Service Bulletin 670BA-32-039, dated February 29, 2012.

(iv) Bombardier Service Bulletin 670BA-32-052, dated February 9, 2015.

(3) For service information identified in this AD, contact MHI RJ Aviation
    ULC, 12655 Henri-Fabre Blvd., Mirabel, Quebec J7N 1E1 Canada; Widebody
    Customer Response Center North America toll-free telephone +1-844-272-
    2720 or direct-dial  telephone +1-514-855-8500;  fax  +1-514-855-8501;
    email thd.crj@mhirj.com;  internet  https://eservices.aero.bombardier.
    com.

(4) You may view this service information at the FAA,  Airworthiness Prod-
    ucts 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 refer-
    ence at the National Archives and Records Administration  (NARA).  For
    information on the availability  of this material  at NARA,  email fr.
    inspection@nara.gov or go to https://www.archives.gov/federal-register
    /cfr/ibr-locations.html.

Issued on September 30, 2021.  Ross Landes, Deputy Director for Regulatory
Operations,  Compliance & Airworthiness Division,  Aircraft  Certification
Service.

FOR FURTHER INFORMATION CONTACT:   Darren  Gassetto,  Aerospace  Engineer,
Mechanical Systems and Administrative Services Section, FAA,  New York ACO
Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-
228-7323; 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-2021-0309; Project Identifier MCAI-2020-00918-T;
Amendment 39-21730; AD 2021-19-12]
RIN 2120-AA64

Airworthiness Directives; MHI RJ Aviation ULC (Type Certificate
Previously Held by Bombardier, Inc.) Airplanes

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

ACTION: Final rule.

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

SUMMARY: The FAA is adopting a new airworthiness directive (AD) for MHI
RJ Aviation ULC Model CL-600-2C10 (Regional Jet Series 700, 701 & 702),
CL-600-2C11 (Regional Jet Series 550), CL-600-2D15 (Regional Jet Series
705), CL-600-2D24 (Regional Jet Series 900), and CL-600-2E25 (Regional
Jet Series 1000) airplanes. This AD was prompted by reports and a
design review indicating that there could be possible corrosion on the
main landing gear (MLG) outer cylinder at the interface with the gland
nut on the shock strut installation and on the forward and aft trunnion
pins in the MLG dressed shock strut assembly. This AD requires detailed
inspections for corrosion on the MLG outer cylinder assemblies, certain
MLG dressed shock strut assemblies, and the MLG outer cylinder at the
gland nut threads, thread relief groove, and chamfer; a detailed
inspection for the presence of corrosion-inhibiting compound (CIC) on
the MLG forward and aft trunnion pins and grease adapter assemblies;
applicable corrective actions; application of primer, paint, and CIC as
applicable; re-identification of certain part numbers; and marking of
the MOD STATUS field of the nameplate of certain parts. The FAA is
issuing this AD to address the unsafe condition on these products.

DATES: This AD is effective November 10, 2021.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of November 10,
2021

ADDRESSES: For service information identified in this final rule,
contact MHI RJ Aviation ULC, 12655 Henri-Fabre Blvd., Mirabel,
Quebec J7N 1E1 Canada; Widebody Customer Response Center North
America toll-free telephone +1-844-272-2720 or direct-dial telephone
+1-514-855-8500; fax +1-514-855-8501; email thd.crj@mhirj.com; internet https://eservices.aero.bombardier.com.

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. It is also available on the internet at https://
www.regulations.gov by searching for and locating Docket No. FAA-2021-
0309.

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-2021-
0309; 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: Darren Gassetto, Aerospace Engineer,
Mechanical Systems and Administrative Services Section, FAA, New York
ACO Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
telephone 516-228-7323; fax 516-794-5531; email 9-avs-nyaco-cos@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued TCCA AD CF-2019-17R1, dated June 18,
2020 (TCCA AD CF-2019-17R1, dated June 18, 2020) (also referred to as
the Mandatory Continuing Airworthiness Information, or the MCAI), to
correct an unsafe condition for MHI RJ Aviation ULC (type certificate
previously held by Bombardier, Inc.) Model CL-600-2C10 (Regional Jet
Series 700, 701 & 702) airplanes, Model CL-600-2C11 (Regional Jet
Series 550) airplanes, Model CL-600-2D15 (Regional Jet Series 705)
airplanes, CL-600-2D24 (Regional Jet Series 900) airplanes, and Model
CL-600-2E25 (Regional Jet Series 1000) 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-2021-0309.
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to MHI RJ Aviation ULC
Model CL-600-2C10 (Regional Jet Series 700, 701 & 702), CL-600-2C11
(Regional Jet Series 550), CL-600-2D15 (Regional Jet Series 705), CL-
600-2D24 (Regional Jet Series 900), and CL-600-2E25 (Regional Jet
Series 1000) airplanes. The NPRM published in the Federal Register on
April 20, 2021 (86 FR 20461). The NPRM was prompted by reports and a
design review indicating that there could be corrosion on the MLG outer
cylinder assemblies and certain MLG dressed shock strut assemblies;
primer was not correctly applied at the gland nut thread relief groove
and chamfer areas on certain MLG outer cylinders during production; and
CIC was inadvertently removed from certain MLG forward and aft trunnion
pins and grease adapter assemblies during maintenance. The NPRM
proposed to require detailed inspections for corrosion on the MLG outer
cylinder assemblies, certain MLG dressed shock strut assemblies, and
the MLG outer cylinder at the gland nut threads, thread relief groove,
and chamfer; a detailed inspection for the presence of CIC on the MLG
forward and aft trunnion pins and grease adapter assemblies; applicable
corrective actions; application of primer, paint, and CIC as
applicable; re-identification of certain part numbers; and marking of
the MOD STATUS field of the nameplate of certain parts. The FAA is
issuing this AD to address undetected corrosion on the MLG forward and
aft trunnion pins, and the gland nut interface on certain MLG outer
cylinders, which could result in an MLG collapse. See the MCAI for
additional background information.

Comments

The FAA gave the public the opportunity to participate in
developing this final rule. The following presents the comments
received on the NPRM and the FAA's response to each comment.

Support for the NPRM

Air Line Pilots Association, International (ALPA) stated that it
supports the NPRM.

Request to Separate the Proposed AD Into Two Separate AD Actions

SkyWest Airlines (SkyWest) requested that the proposed AD be
separated into two AD actions. The commenter recommended that one AD
address the MLG outer cylinder assemblies and dressed shock strut
assemblies and the other AD address the MLG forward and aft trunnion
pins. The commenter stated that there are multiple service bulletins
and requirements specified in the proposed AD that are related to
different MLG components.
The FAA disagrees with the commenter's request. The FAA
acknowledges that this AD includes requirements for different MLG
components and specifies multiple service bulletins; however, these MLG
components are interrelated. In order to address the identified unsafe
condition the requirements must be completed at the same time. In
addition, the AD body is organized to facilitate an owner/operator's
compliance with the requirements of this AD. Each header for paragraphs
(g) through (k) of this AD identifies the affected MLG component and
the applicable actions. The FAA has not changed this AD in regard to
this issue.

Request To Allow Credit for Vendor Service Bulletins

SkyWest requested that paragraph (l) of the proposed AD, Credit for
Previous Actions, be revised to include the applicable vendor service
bulletins published by Goodrich. The commenter stated that this would
alleviate the need to request multiple alternative methods of
compliance (AMOCs) for airplanes on which the MLG gear is returned from
overhaul with only the actions described in the Goodrich service
bulletins accomplished rather that the actions described in the
corresponding Bombardier service bulletins. The commenter noted that
each Bombardier service bulletin specified in paragraph (l) of the
proposed AD refers to a corresponding Goodrich service bulletin.
The FAA agrees to clarify what must be done if certain actions
required by this AD have already been accomplished. Paragraph (f) of
this AD states ``Comply with this AD within the compliance times
specified, unless already done.'' If an operator has already
accomplished some of the actions required by this AD then only the
remaining actions need to be completed. Therefore, for airplanes that
have already incorporated the actions described in UTC Aerospace
Systems (Goodrich Aerospace Canada Ltd) Service Bulletin 49101-32-72,
Goodrich Service Bulletin 49200-32-44, or Goodrich Service Bulletin
49200-32-80 prior to the effective date of this AD, only the remaining
requirements described in the corresponding Bombardier service
bulletins need to be completed on those airplanes.
The FAA does not agree with granting complete credit for the
actions required by paragraphs (g), (i), and (j) of this AD using only
the procedures described in the applicable Goodrich service
bulletins. There are additional actions required for these inspections,
including corrective actions and operational tests, that are included
in the Bombardier service bulletins but not in the corresponding
Goodrich service bulletins.
In regards to paragraph (l) in this AD, Credit for Previous
Actions, the intent of that paragraph is to provide credit for actions
required by paragraphs (g), (h), and (j) of this AD if those actions
were performed before the effective date of this AD using the certain
earlier revisions of the applicable Bombardier service bulletins
specified in paragraph (l) of this AD or equivalent service
information. The FAA has not changed this AD in regard to this issue.

Conclusion

The FAA reviewed the relevant data, considered the comments
received, 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 has issued the following service information.
Service Bulletin 670BA-32-024, Revision C, dated February
11, 2015, which describes procedures for a detailed visual inspection
of the MLG outer cylinder assemblies and dressed shock strut assemblies
for corrosion of the outer cylinder gland nut thread interface and
relief area, and corrective actions including repair and corrosion
removal.
Service Bulletin 670BA-32-034, Revision B, dated December
21, 2018, which describes procedures for a detailed visual inspection
of the inside diameter of the MLG trunnion pins for discrepancies
including the condition of paint and CIC and evidence of corrosion, and
corrective actions including replacement and rework of the trunnion
pins as applicable.
Service Bulletin 670BA-32-039, dated February 29, 2012,
which describes procedures for inspections of the inner diameter of the
MLG forward and aft trunnion pins for discrepancies including corrosion
and inadequate CIC, and corrective actions including application of CIC
and replacement of corroded forward and aft trunnion pins with
serviceable parts.
Service Bulletin 670BA-32-052, dated February 9, 2015,
which describes procedures for a detailed visual inspection of the
gland nut thread relief groove and chamfer surface for the condition of
the protective coating and for discrepancies including evidence of
corrosion or rework at the gland nut thread relief groove and chamfer
surface of the MLG shock strut outer cylinder assemblies, and
corrective actions including corrosion removal.
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.

Differences Between This AD and the MCAI or Service Information

Although certain service information specifies to return damaged
MLG trunnion pins to Goodrich Landing Gear, that action would not be
required by this AD.

Costs of Compliance

The FAA estimates that this AD affects 562 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:

Estimated Costs for Required Actions

Labor cost
Parts cost
Cost per product
Cost on U.S. operators
Up to 100 work-hours x $85 per hour = Up to $8,500
Up to $36,604
Up to $45,104
Up to $25,348,448

According to the manufacturer, some or all of the costs of this AD
may be covered under warranty, thereby reducing the cost impact on
affected operators. The FAA does not control warranty coverage for
affected operators. As a result, the FAA has included all known costs
in the 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.
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

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 adding the following new airworthiness
directive: