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2021-10-13 DE HAVILLAND AIRCRAFT OF CANADA LIMITED (TYPE CERTIFICATE PREVIOUSLY HELD BY BOMBARDIER, INC.): Amendment 39-21546; Docket No. FAA-2021-0018; Project Identifier MCAI-2020-01214-T.
(a) EFFECTIVE DATE

    This airworthiness directive (AD) is effective July 1, 2021.

(b) AFFECTED ADS

    This  AD  replaces AD  2015-17-08,  Amendment  39-18241  (80 FR 51459,
    August 25, 2015) (AD 2015-17-08).

(c) APPLICABILITY

    This AD applies to De Havilland Aircraft of Canada Limited  Model DHC-
    8-401 and -402 airplanes, certificated in any category, serial numbers
    4001, and 4003 through 4608 inclusive.

(d) SUBJECT

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

(e) REASON

    This AD was prompted by a report indicating that several failure modes
    of the nose wheel steering (NWS) system may cause the loss of feedback
    from both  rotary variable  differential transformers  to the steering
    control unit. The FAA is issuing  this AD to address failure modes  of
    the NWS system, which could  lead to NWS runaway, loss  of directional
    control of the airplane, and possible consequent runway excursion.

(f) COMPLIANCE

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

(g) NEW REQUIREMENT OF THIS AD

    Within 4,000 flight hours  or 18 months,  whichever occurs first after
    the effective date of this AD: Perform modifications to the NWS system
    in accordance with paragraph 3.B of the Accomplishment Instructions of
    De Havilland Aircraft of Canada Limited  Service  Bulletin  84-32-162,
    Revision B,  dated November 13, 2019,  including UTC Aerospace Systems
    Service Bulletin 406300-32-142, dated June 24, 2019; and UTC Aerospace
    Systems Service Bulletin 406330-32-143, dated June 24, 2019.

(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 De Havilland Aircraft of Canada Limited Service Bull-
    etin 84-32-162, dated August 26, 2019, including UTC Aerospace Systems
    Service Bulletin 406300-32-142, dated June 24, 2019, and UTC Aerospace
    Systems Service Bulletin 406330-32-143,  dated  June 24, 2019;  or  De
    Havilland  Aircraft  of  Canada  Limited  Service  Bulletin 84-32-162,
    Revision A,  dated October 18, 2019,  including  UTC Aerospace Systems
    Service Bulletin 406300-32-142, dated June 24, 2019, and UTC Aerospace
    Systems Service Bulletin 406330-32-143, dated June 24, 2019.

(i) 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
    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.

(j) RELATED INFORMATION

(1) Refer to Mandatory Continuing Airworthiness Information (MCAI) TCCA AD
    CF-2020-28, dated August 14, 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-
    0018.

(2) For more information about this AD, contact Siddeeq Bacchus, Aerospace
    Engineer, Mechanical Systems and Administrative Services Section, FAA,
    New York ACO Branch, 1600 Stewart Ave., Suite 410, Westbury, NY 11590;
    telephone 516-228-7362;  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 (k)(3)
    and (4) of this AD.

(k) 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) De Havilland  Aircraft of Canada  Limited  Service Bulletin 84-32-162,
    Revision B,  dated November 13, 2019,  including UTC Aerospace Systems
    Service Bulletin 406300-32-142, dated June 24, 2019; and UTC Aerospace
    Systems Service Bulletin 406330-32-143, dated June 24, 2019.

(ii) [Reserved]

(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 April 30, 2021. Lance T. Gant, Director, Compliance & Airworthi-
ness Division, Aircraft Certification Service.

FOR FURTHER INFORMATION CONTACT:  Siddeeq  Bacchus,   Aerospace  Engineer,
Mechanical Systems and Administrative Services Section, FAA,  New York ACO
Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-
228-7362; 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-2021-0018; Project Identifier MCAI-2020-01214-T;
Amendment 39-21546; AD 2021-10-13]
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) 2015-17-
08, which applied to certain Bombardier, Inc. Model DHC-8-400 series
airplanes. AD 2015-17-08 required installing new cable assemblies with
a pull-down resistor. This AD requires modifications to the nose wheel
steering (NWS) system. This AD was prompted by a report indicating that
several failure modes of the NWS system may cause the loss of feedback
from both rotary variable differential transformers to the steering
control unit. The FAA is issuing this AD to address the unsafe
condition on these products.

DATES: This AD is effective July 1, 2021.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of July 1,
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 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-2021-0018.

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-
0018; 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: Siddeeq Bacchus, Aerospace Engineer,
Mechanical Systems and Administrative Services Section, FAA, New York
ACO Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
telephone 516-228-7362; 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 TCCA AD CF-2020-28, dated August 14,
2020 (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-8-401 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-2021-0018.
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 to supersede AD 2015-17-08, Amendment 39-18241 (80 FR
51459, August 25, 2015) (AD 2015-17-08). AD 2015-17-08 applied to
certain Bombardier, Inc. Model DHC-8-400 series airplanes. The NPRM
published in the Federal Register on February 24, 2021 (86 FR 11175).
The NPRM was prompted by a report indicating that several failure modes
of the NWS system may cause the loss of feedback from both rotary
variable differential transformers to the steering control unit. The
NPRM proposed to require modifications to the NWS system. The FAA is
issuing this AD to address failure modes of the NWS system, which could
lead to NWS runaway, loss of directional control of the airplane, and
possible consequent runway excursion. See the MCAI for additional
background information.

Comments

The FAA gave the public the opportunity to participate in
developing this final rule. The FAA has considered the comment
received. The Air Line Pilots Association, International (ALPA)
indicated its support for the NPRM.

Conclusion

The FAA reviewed the relevant data, considered the comment
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 Service Bulletin
84-32-162, Revision B, dated November 13, 2019, including UTC Aerospace
Systems Service Bulletin 406300-32-142, dated June 24, 2019; and UTC
Aerospace Systems Service Bulletin 406330-32-143, dated June 24, 2019.
This service information describes procedures for modifying the NWS
system (terminating wiring, reworking the left-hand console frame, and
installing an NWS electronic control unit and NWS hand control). 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
Modification 13 work-hours x $85 per hour = $1,105 Up to $122 Up to $1,227 Up to $66,258

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:

a. Removing Airworthiness Directive (AD) 2015-17-08, Amendment 39-18241
(80 FR 51459, August 25, 2015); and

b. Adding the following new AD: