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PROPOSED AD DE HAVILLAND AIRCRAFT OF CANADA LIMITED (TYPE CERTIFICATE PREVIOUSLY HELD BY BOMBARDIER, INC.): Docket No. FAA-2021-0514; Project Identifier MCAI-2020-01570-T.
(a) COMMENTS DUE DATE

    The FAA must receive  comments on this airworthiness directive (AD) by
    August 13, 2021.

(b) AFFECTED ADS

    None.

(c) APPLICABILITY

    This AD applies to De Havilland Aircraft of Canada Limited  (type cer-
    tificate previously held  by Bombardier, Inc.)  Model DHC-8-400, -401,
    and -402 airplanes, certificated in any category, serial numbers 4001,
    4003 through 4550 inclusive, 4583 through 4585 inclusive,  4587, 4588,
    and 4590.

(d) SUBJECT

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

(e) UNSAFE CONDITION

    This AD was prompted by a report that the epoxy primer on the internal
    bore of the nacelle and landing gear attachment pins was not  applied,
    and corrosion on  the internal bore  of the wing  rear spar attachment
    pins  was found.  The  FAA  is issuing  this AD  to address  premature
    corrosion and subsequent  failure of the  nacelle to landing  gear and
    nacelle to rear wing spar attachment pins, which if undetected,  could
    lead to a single or dual collapse of the main landing gear.

(f) COMPLIANCE

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

(g) INSPECTION AND CORRECTIVE ACTIONS

(1) At the applicable compliance times specified  in  paragraphs (g)(1)(i)
    through  (iii) of  this AD:  Do a  detailed visual  inspection of  the
    nacelle to wing rear spar attachment pins, and the nacelle and landing
    gear  attachment  pins, for  any  cracking or  corrosion,  and do  all
    applicable corrective actions, in accordance with Part A or Part B, as
    applicable,  of  Section  3.,  "Accomplishment  Instructions,"  of the
    applicable service information specified in figure 1 to paragraph  (g)
    of  this  AD.  Do all  applicable  corrective  actions before  further
    flight.

                FIGURE 1 TO PARAGRAPH (G) – SERVICE INFORMATION           
    ______________________________________________________________________
        SERIAL NUMBERS–                    SERVICE INFORMATION–
    ______________________________________________________________________
    4001, 4003 through 4550        De Havilland Service Bulletin 84-54-28,
    inclusive                      Revision B, dated January 24, 2020

    4001, 4003 through 4533        De Havilland Service Bulletin 84-54-31,
    inclusive, 4583 through        Revision B, dated February 21, 2020
    4585 inclusive, 4587,
    4588 and 4590
    ______________________________________________________________________

(i) For nacelle to wing rear spar attachment pins,  or nacelle and landing
    gear attachment pins, as  applicable, that have accumulated  less than
    26,000 flight cycles  as of the  effective date of  this AD, and  have
    been in service less than 12 years from their entry-into-service as of
    the effective date  of this AD:  Prior to the  pins reaching 14  years
    from  their  entry-into-service,  or prior  to  the  airplane reaching
    30,000 total flight cycles, whichever occurs first.

(ii) For nacelle to wing rear spar attachment pins, or nacelle and landing
     gear attachment  pins, as  applicable, that  have accumulated  26,000
     flight cycles or more  as of the effective  date of this AD,  or have
     been in service 12 years or more from their entry-into-service as  of
     the effective date of this AD:  Within 4 years or 8,000 flight  hours
     after the effective date of this AD, whichever occurs first.

(iii) For airplanes  on which the actions specified  in Bombardier Service
      Bulletin 84-54-27, dated August 11, 2017 or Bombardier Service Bull-
      etin 84-54-28,  dated  August 11, 2017;  as  applicable,  have  been
      accomplished: Within 14 years or 30,000 flight cycles after the date
      of  incorporation  of Bombardier  Service  Bulletin 84-54-27,  dated
      August  11, 2017;  or  Bombardier  Service Bulletin  84-54-28, dated
      August 11, 2017; as applicable, whichever occurs first.

(2) For serial numbers  4583,  4584,  4585,  4587,  4588 and 4590:  At the
    applicable compliance times specified in paragraphs (g)(1)(i)  through
    (iii) of this AD, re-part mark the yoke attachment pin, in  accordance
    with Part B of the Accomplishment Instructions of De Havilland Service
    Bulletin 84-54-31, Revision B, dated February 21, 2020.

(h) CREDIT FOR PREVIOUS ACTIONS

    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  the  applicable service  information  specified in
    paragraphs (h)(1) through (3) of this AD.

(1) Bombardier Service Bulletin 84-54-28, Revision A, dated April 10, 2019

(2) Bombardier Service Bulletin 84-54-31, dated May 1, 2019.

(3) Bombardier Service Bulletin 84-54-31,  Revision A,  dated  October 15,
    2019.

(i) NO REPORTING REQUIREMENT

    Although  De Havilland  Service Bulletin 84-54-28,  Revision B,  dated
    January 24, 2020; and De Havilland Service Bulletin 84-54-31, Revision
    B, dated February 21, 2020;  specify to submit  certain information to
    the manufacturer, this AD does not include that requirement.

(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
    responsible  Flight  Standards  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 responsible Flight  Standards
    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  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.

(k) RELATED INFORMATION

(1) Refer to Mandatory Continuing Airworthiness Information (MCAI) TCCA AD
    CF-2020-51R1, dated February 24,  2021, 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-2021-0514.

(2) For more information  about this AD,  contact  Deep Gaurav,  Aerospace
    Engineer, Airframe and Propulsion Section,  FAA,  New York ACO Branch,
    1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-
    7300; 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
    Blvd., 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,  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.

Issued on June 23, 2021.  Lance T. Gant, Director, Compliance & Airworthi-
ness Division, Aircraft Certification Service.

DATES: The FAA must receive comments  on  this  proposed AD  by August 13,
2021.
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0514; Project Identifier MCAI-2020-01570-T]
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 adopt a new airworthiness directive (AD)
for certain De Havilland Aircraft of Canada Limited Model DHC-8-400, -
401, and -402 airplanes. This proposed AD was prompted by a report that
the epoxy primer on the internal bore of the nacelle and landing gear
attachment pins was not applied, and corrosion on the internal bore of
the wing rear spar attachment pins was found. This proposed AD would
require doing a detailed visual inspection of the nacelle to wing rear
spar attachment pins, and the nacelle and landing gear attachment pins,
for any corrosion, and doing all applicable corrective actions. 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 August 13,
2021.

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,
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.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-0514; 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, any comments
received, and other information. The street address for Docket
Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Deep Gaurav, Aerospace Engineer,
Airframe and Propulsion Section, FAA, New York ACO Branch, 1600 Stewart
Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7300; 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 ADDRESSES. Include "Docket No. FAA-2021-0514; Project Identifier
MCAI-2020-01570-T" at the beginning of your comments. The most helpful
comments reference a specific portion of the proposal, explain the
reason for any recommended change, and include supporting data. The FAA
will consider all comments received by the closing date and may amend
the proposal because of those comments.

Except for Confidential Business Information (CBI) as described in
the following paragraph, and other information as described in 14 CFR
11.35, the FAA will post all comments received, without change, to
https://www.regulations.gov, including any personal information you
provide. The agency will also post a report summarizing each
substantive verbal contact received about this NPRM.

Confidential Business Information

CBI is commercial or financial information that is both customarily
and actually treated as private by its owner. Under the Freedom of
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public
disclosure. If your comments responsive to this NPRM contain commercial
or financial information that is customarily treated as private, that
you actually treat as private, and that is relevant or responsive to
this NPRM, it is important that you clearly designate the submitted
comments as CBI. Please mark each page of your submission containing
CBI as "PROPIN." The FAA will treat such marked submissions as
confidential under the FOIA, and they will not be placed in the public
docket of this NPRM. Submissions containing CBI should be sent to Deep
Gaurav, Aerospace Engineer, Airframe and Propulsion Section, FAA, New
York ACO Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
telephone 516-228-7300; fax 516-794-5531; email 9-avs-nyaco-cos@faa.gov.
Any commentary that the FAA receives which is not specifically designated
as CBI will be placed in the public docket for this rulemaking.

Background

Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued TCCA AD CF-2020-51R1, dated February
24, 2021 (also referred to after this as the Mandatory Continuing
Airworthiness Information, or the MCAI), to correct an unsafe condition
for certain De Havilland Aircraft of Canada Limited Model DHC-8-400,
-401, and -402 airplanes. You may examine the MCAI in the AD docket at
https://www.regulations.gov by searching for and locating Docket No.
FAA-2021-0514.

This proposed AD was prompted by a report that the epoxy primer on
the internal bore of the nacelle and landing gear attachment pins was
not applied, and corrosion on the internal bore of the wing rear spar
attachment pins was found. The FAA is proposing this AD to
address premature corrosion and subsequent failure of the nacelle to
landing gear and nacelle to rear wing spar attachment pins, which if
undetected, could lead to a single or dual collapse of the main landing
gear. See the MCAI for additional background information.

Related Service Information Under 1 CFR Part 51

De Havilland Aircraft of Canada Limited has issued-Service Bulletin
84-54-28, Revision B, dated January 24, 2020; and Service Bulletin 84-
54-31, Revision B, dated February 21, 2020. This service information
describes procedures for doing a detailed visual inspection of the
nacelle to wing rear spar attachment pins, and the nacelle and landing
gear attachment pins, for any corrosion; and doing all applicable
corrective actions. Corrective actions include applying epoxy primer to
the bore surface of the pins, a fluorescent magnetic particle
inspection for any cracking, corrosion removal, reworking and part
marking certain pins, and replacing any cracked or corroded pins with
serviceable pins. These documents are distinct since they apply to
different airplane configurations.

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 the FAA's 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 FAA 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 AD Requirements in This NPRM

This proposed AD would require accomplishing the actions specified
in the service information already described.

Differences Between This Proposed AD and the MCAI or Service
Information


Where Part III of TCCA CF-2020-51R1, dated February 24, 2021,
specifies a detailed visual inspection and rectification of the nacelle
and landing gear attachment pins, this AD requires a re-part mark of
the yoke attachment pin as specified in Part B of the Accomplishment
Instructions of De Havilland Service Bulletin 84-54-31, Revision B,
dated February 21, 2020.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 41 airplanes of U.S. registry. The FAA estimates the following
costs to comply with this proposed AD:

Estimated Costs for Required Actions

Labor cost
Parts cost
Cost per product
Cost on U.S. operators
Up to 9 work-hours x $85 per hour = Up to $765
$0
Up to $765
Up to $31,365

The FAA has received no definitive data on which to base the cost
estimates for the on-condition actions specified in this proposed AD.

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 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) Would not affect intrastate aviation in Alaska, and

(3) Would 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: