preamble attached >>>
ADs updated daily at www.Tdata.com
2021-11-04 DE HAVILLAND AIRCRAFT OF CANADA LIMITED (TYPE CERTIFICATE PREVIOUSLY HELD BY BOMBARDIER, INC.):
Amendment 39-21566; Docket No. FAA-2020-0975;
Project Identifier 2020-NM-061-AD.

(a) EFFECTIVE DATE

    This airworthiness directive (AD) is effective July 9, 2021.

(b) AFFECTED AIRWORTHINESS DIRECTIVES (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,  having serial num-
    bers 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 al-
    ready 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)  PART  NUMBER
    (P/N) 30145-0601

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

(i) INSTALLATION OF PSEU P/N 30145-0602

    Installing PSEU P/N 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) or (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 P/N 30145-0601 was installed  before the
    effective date of this AD using the service information  as  specified
    in paragraphs (j)(2)(i) or (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  Limitedís   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)  TCCA
    AD CF-2016-31R1, dated March  24, 2017, 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-2020-0975.

(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-nyacocos@
    faa.gov.

(3) Service information identified in this AD  that is not incorporated by
    reference is available at the addresses specified in paragraphs (m)(3)
    and (4) of this AD.

(m) 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 84-32-140,  Revision B,  dated January 30,
    2018.

(ii) Bombardier Service Bulletin 84-32-143, Revision B, dated November 16,
     2016.

(iii) Bombardier Service Bulletin 84-32-149, dated November 16, 2016.

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

(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 fedreg
    .legal@nara.gov,  or go to: https://www.archives.gov/federal-register/
    cfr/ibr-locations.html.

Issued on May 27, 2021. Ross Landes, Deputy Director for Regulatory Opera-
tions, 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-nyacocos@faa.gov.
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0975; Project Identifier 2020-NM-061-AD; Amendment
39-21566; AD 2021-11-04]
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 adopting a new airworthiness directive (AD) for
certain De Havilland Aircraft of Canada Limited Model DHC-8-400, -401,
and -402 airplanes. 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. This AD requires 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, corrective actions, and
installation of a new, improved proximity sensor electronic unit (PSEU)
with software changes. The FAA is issuing this AD to address the unsafe
condition on these products.

DATES: This AD is effective July 9, 2021.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of July 9, 2021.

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 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-2020-0975.

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 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-nyacocos@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued TCCA AD CF-2016-31R1, dated March 24,
2017 (TCCA AD CF-2016-31R1) (also referred to 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.
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to certain De Havilland
Aircraft of Canada Limited Model DHC-8-400, -401, and -402 airplanes.
The NPRM published in the Federal Register on November 2, 2020 (85 FR
69276). The NPRM was prompted by a report of MLG retractions after
striking an obstacle or severe wheel imbalance after a tire failure.
The NPRM proposed to 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, corrective actions, and installation of a new improved PSEU
with software changes. 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 (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.

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.

Request To Exclude Certain Steps of the Accomplishment Instructions of
Service Information


Horizon Air requested that paragraphs (g), (h), and (i) of the
proposed AD be revised to require only paragraph 3.B. of the
Accomplishment Instructions of the service bulletins referenced in
those paragraphs. Horizon Air stated that the Job Set-up section
(paragraph 3.A.) of the Accomplishment Instructions do not directly
address the unsafe condition. Horizon Air also asserted that retaining
the Job Set-up sections restricts an operator's ability to do other
maintenance in conjunction with the required service bulletins.
The FAA disagrees with the request to exclude paragraph 3.A., Job
Set-up, of the Accomplishment Instructions from this AD's requirements. The Job
Set-up sections of the required service bulletins include specific
procedures for the electrical power and proper configurations of the
nose landing gear (NLG) and MLG, which are necessary for accomplishing
the applicable corrective actions on the PSEUs and proximity detectors
and to prevent possible damage to that equipment. Requiring the Job
Set-up instructions should not, in general, restrict the ability to
schedule other maintenance actions in conjunction with the required
actions. The FAA has not changed this AD in this regard.

Request To Allow Use of Alternative Service Information When Installing
a Certain Part


Horizon Air requested that paragraph (i) of the proposed AD be
revised to also allow installation of PSEU part number (P/N) 30145-0602
in accordance with Bombardier Service Bulletin 84-32-143, Revision B,
dated November 16, 2016. Horizon Air pointed out that both documents
stated that operators may receive a PSEU with P/N 30145-0601 or 30145-
0602. Further, Horizon Air noted that PSEU P/N 30145-0602 is ``two-way
interchangeable'' with P/N 30145-0601, and that the installation
instructions are the same in both service bulletins.
The FAA disagrees with the request to revise paragraph (i) of this
AD. The FAA agrees that the service information does state a two-way
interchangeability of PSEU P/N 30145-0601 with PSEU P/N 30145-0602 and
that operators may receive either PSEU P/N due to component
availability. However, the service information also states that those
in receipt of a PSEU must declare the appropriate service information
specific to the PSEU P/N. In addition, while most of the Accomplishment
Instructions between Bombardier Service Bulletin 84-32-143, Revision B,
dated November 16, 2016, and Bombardier Service Bulletin 84-32-149,
dated November 16, 2016, are the same, they are not identical.
Therefore, recording compliance with another service bulletin would not
be in compliance with the applicable corrective actions for the PSEU P/
N. The FAA has not changed the AD in this regard.

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

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, P/N
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, P/N 30145-0602,
with software changes.
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 57 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 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

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: