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PROPOSED AD DE HAVILLAND AIRCRAFT OF CANADA LIMITED (TYPE CERTIFICATE PREVIOUSLY HELD BY BOMBARDIER, INC.): Docket No. FAA-2020-0975; Product Identifier 2020-NM-061-AD.
(a) COMMENTS DUE DATE

    The FAA must receive comments by December 17, 2020.

(b) AFFECTED ADS

    None.

(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, having  serial
    number 4001, and 4003 through 4534 inclusive.

(d) SUBJECT

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

(e) REASON

    This  AD  was  prompted  by  a  report  of  main  landing  gear  (MLG)
    retractions after striking an obstacle or severe wheel imbalance after
    a tire  failure. The  FAA is  issuing this  AD to  address loss of MLG
    downlock  signal caused  by the  vibrations from  those events,  which
    leads to de-energizing the MLG solenoid sequence valve and  subsequent
    removal of hydraulic pressure from the MLG downlock actuator. Loss  of
    the hydraulic  pressure in  the downlock  actuator, combined  with the
    vibrations, can cause  the stabilizer brace  to unlock and  the MLG to
    subsequently retract.

(f) COMPLIANCE

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

(g) DOWNLOCK SENSOR RIGGING AND REDUCED LOCK LINK OVER-CENTER

    Within 9 months after the effective  date of this AD: Verify both  the
    height of the lock link over-center  stop pin and the gap of  the left
    -hand  and  right-hand  MLG downlock  proximity  sensors,  and perform
    corrective actions as required, in accordance with paragraphs 3.A. and
    3.B. of the Accomplishment Instructions of Bombardier Service Bulletin
    84-32-140,  Revision  B, dated  January  30, 2018.  Do  all applicable
    corrective actions before further flight.

(h) INSTALLATION OF PROXIMITY SENSOR ELECTRONIC UNIT (PSEU) 30145-0601

    Within 18  months after  the effective  date of  this AD, install PSEU
    30145-0601  in  accordance  with  paragraphs  3.A.  and  3.B.  of  the
    Accomplishment Instructions of Bombardier Service Bulletin  84-32-143,
    Revision B, dated November 16, 2016.

(i) INSTALLATION OF PSEU 30145-0602

    Installing PSEU 30145-0602 in accordance with paragraphs 3.A. and 3.B.
    of the Accomplishment Instructions  of Bombardier Service Bulletin  84
    -32-149, dated November 16,  2016, also accomplishes the  requirements
    of paragraphs (g) and (h) of this AD.

(j) 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 the service  information as specified  in paragraphs
    (j)(1)(i) and (ii) of this AD.

(i) Bombardier Service Bulletin 84-32-140, dated August 5, 2016.

(ii) Bombardier Service Bulletin 84-32-140,  Revision  A,  dated  June 12,
     2017.

(2) This paragraph provides credit for actions required  by paragraphs (g)
    and  (h) of  this AD,  if  PSEU  30145-0601 was  installed before  the
    effective date of this AD  using the service information as  specified
    in paragraphs (j)(2)(i) and (ii) of this AD.

(i) Bombardier Service Bulletin 84-32-143, dated June 30, 2016.

(ii) Bombardier Service Bulletin 84-32-143,  Revision A,  dated  August 5,
     2016.

(k) 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  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.

(l) RELATED INFORMATION

(1) Refer   to   Mandatory  Continuing  Airworthiness  Information  (MCAI)
    Canadian AD CF-2016-31R1,  dated March 24, 2017,  for related informa-
    tion.  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-2020-0975.

(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.

(3) For information about AMOCs, contact 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.

(4) 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,
    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 October 26, 2020. Lance T Gant, Director, Compliance & Airworth-
iness Division, Aircraft Certification Service.

DATES: The FAA must receive comments on this proposed AD  by  December 17,
2020.
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0975; Product Identifier 2020-NM-061-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 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 of main landing gear (MLG) retractions after
striking an obstacle or severe wheel imbalance after a tire failure.
This proposed AD would require inspections for correct height of the
lock link over-center stop pin and for correct gaps of the left-hand
and right-hand MLG downlock proximity sensors, replacement of the shim
if necessary, and corrective actions, and installation of a new
improved proximity sensor electronic unit (PSEU) with software changes.
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 December
17, 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,
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 on the internet at https://www.regulations.
gov by searching for and locating Docket No. FAA-2020-0975;
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. Comments will be
available in the AD docket shortly after receipt.

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:

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-2020-0975;
Product Identifier 2020-NM-061-AD" 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 proposed AD.

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
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. Any commentary that the FAA
receives which is not specifically designated as CBI will be placed in
the public docket for this rulemaking.

Discussion

Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian AD CF-2016-31R1, dated March
24, 2017 (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 on the internet at https://www.regulations.gov by searching for
and locating Docket No. FAA-2020-0975.

This proposed AD was prompted by a report of MLG retractions after
striking an obstacle or severe wheel imbalance after a tire failure.
The FAA is proposing this AD to address loss of MLG downlock signal
caused by the vibrations from those events, which leads to de-
energizing the MLG solenoid sequence valve (SSV) and subsequent removal
of hydraulic pressure from the MLG downlock actuator. Loss of the
hydraulic pressure in the downlock actuator, combined with the
vibrations, can cause the stabilizer brace to unlock and the MLG to
subsequently retract. See the MCAI for additional background
information.

Related Service Information Under 1 CFR Part 51

De Havilland Aircraft of Canada Limited has issued Bombardier
Service Bulletin 84-32-140, Revision B, dated January 30, 2018. This
service information describes set-up procedures for proper
configuration of the MLG prior to performing subsequent procedures for
inspections for correct height of the lock link over-center stop pin
and for correct gaps of the left-hand and right-hand MLG downlock
proximity sensors, and replacement of the shim.

De Havilland Aircraft of Canada Limited has also issued Bombardier
Service Bulletin 84-32-143, Revision B, dated November 16, 2016, which
describes procedures for installation of a new, improved PSEU, PSEU
30145-0601, with software changes.

De Havilland Aircraft of Canada Limited has also issued Bombardier
Service Bulletin 84-32-149, dated November 16, 2016, which describes
procedures for installation of a new, improved PSEU, PSEU 30145-0602,
with software changes.

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 Requirements of This NPRM

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

Costs of Compliance

The FAA estimates that this proposed AD affects 57 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 12 work-hours x $85 per hour = Up to $1,020 Up to $4,750 Up to $5,770 Up to $328,890

The FAA estimates the following costs to do any necessary on-
condition actions that would be required based on the results of any
required actions. The FAA has no way of determining the number of
aircraft that might need these on-condition actions:

Estimated Costs of On-Condition Actions

Labor cost
Parts cost
Cost per product
1 work-hour x $85 per hour = $85
$374
$459

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) 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 adding the following new airworthiness
directive (AD):