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2021-23-03 DE HAVILLAND AIRCRAFT OF CANADA LIMITED (TYPE CERTIFICATE PREVIOUSLY HELD BY BOMBARDIER, INC.):
Amendment 39-21801; Docket No. FAA-2021-0613; Project Identifier MCAI-2020-01431-T.

(a) EFFECTIVE DATE

    This airworthiness directive (AD) is effective December 6, 2021.

(b) AFFECTED ADS

    None.

(c) APPLICABILITY

    This  AD  applies  to  De Havilland Aircraft of Canada  Limited  Model
    DHC-8-400, -401, and -402 airplanes,  certificated  in  any  category,
    serial numbers 4001, 4003, and subsequent.

(d) SUBJECT

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

(e) UNSAFE CONDITION

    This AD was prompted by a  report of cracking found on a  main landing
    gear (MLG) drag strut assembly. The FAA is issuing this AD to  address
    cracking of  the MLG  drag strut  assembly and  possible failure under
    compression loads  during landing  or ground  operations, which  could
    result in asymmetric MLG configuration and potential runway excursion.

(f) COMPLIANCE

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

(g) RECORDS REVIEW, REPETITIVE INSPECTIONS, AND ON-CONDITION ACTIONS

    Within 30 days after the effective date of this AD: Review the applic-
    able airplane  maintenance records  to determine  if any  affected MLG
    drag strut assembly identified in figure 1 to the introductory text of
    paragraph (g) of this AD is installed. If any affected MLG drag  strut
    assembly is installed, do  the actions specified in  paragraphs (g)(1)
    and (2) of this AD.

    FIGURE 1 TO THE INTRODUCTORY TEXT OF PARAGRAPH (G) - AFFECTED MLG DRAG
                                                         STRUT ASSEMBLY   
    ______________________________________________________________________
            PART NO.                                   SERIAL NO.
    ______________________________________________________________________
            46301-13                                    MBM0056
                                                        MBM0073
                                                        MBM0076
                                                        MBM0130
                                                        MBM0136
                                                        MBM0145
                                                        MBM0179
                                                        MBM0204
                                                        MBM0208
                                                        MBM0302
                                                        MBM0303
                                                        MBM0324
                                                        MBM0405
                                                        MBM0408
                                                        MBM0412
                                                        MBM0417
                                                        MBM0423
    ______________________________________________________________________

(1) Within 80 flight hours after accomplishing the records review required
    by paragraph (g) of this AD, do a detailed inspection for cracking  of
    the  affected  MLG  drag  strut assembly,  and  do  all  applicable on
    -condition actions before further flight, in accordance with a  method
    approved  by  the  Manager,  New  York  ACO  Branch,  FAA.  Repeat the
    inspection thereafter at intervals not to exceed 80 flight hours until
    the magnetic particle inspection required by paragraph (g)(2) of  this
    AD is done.

Note 1 to paragraph (g)(1):  Guidance on the inspections and  on-condition
actions  required  by this  AD  can be  found  in Transport  Canada  Civil
Aviation (TCCA) AD CF-2020-43, dated October 21, 2020.

(2) Within 1,600 flight hours  or  12 months  after  the effective date of
    this  AD,  whichever  occurs   first,  perform  a  magnetic   particle
    inspection for cracks  of the entire  tubular section of  the affected
    MLG  drag  strut  assembly, and  do  all  on-condition actions  before
    further flight, in accordance with  a method approved by the  Manager,
    New York ACO Branch, FAA. Performing the magnetic particle  inspection
    required  by  this   paragraph  terminates  the   repetitive  detailed
    inspections required by paragraph (g)(1) of this AD.

(h) PARTS INSTALLATION PROHIBITION

    As of the effective date of this AD, no person may install an affected
    MLG drag  strut assembly  identified in  figure 1  to the introductory
    text  of  paragraph  (g)  of  this  AD  on  any  airplane  unless  the
    inspections  and  applicable  on-conditions  specified  in  paragraphs
    (g)(1) and (2) of this AD are done before further flight.

(i) 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.

(j) RELATED INFORMATION

(1) Refer to Mandatory Continuing Airworthiness Information (MCAI) TCCA AD
    CF-2020-43, dated October 21, 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-
    0613.

(2) For more information about this AD, contact Aziz Ahmed, Aerospace Eng-
    ineer, Airframe and Propulsion Section, FAA, New York ACO Branch, 1600
    Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7329;
    fax 516-794-5531; email 9-avs-nyaco-cos@faa.gov.

(3) For information about TCCA AD CF-2020-43, dated October 21, 2020, con-
    tact TCCA, Transport Canada National Aircraft Certification, 159 Cleo-
    patra Drive, Nepean, Ontario K1A 0N5, Canada;  telephone 888-663-3639;
    email AD-CN@tc.gc.ca;  internet https://tc.canada.ca/en/aviation.  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.

(k) MATERIAL INCORPORATED BY REFERENCE

    None.

Issued on October 26, 2021. Lance T Gant, Director, Compliance & Airworth-
iness Division, Aircraft Certification Service.

FOR FURTHER INFORMATION CONTACT: Aziz Ahmed, Aerospace Engineer,  Airframe
and Propulsion Section, FAA, New York ACO Branch, 1600 Stewart Ave., Suite
410, Westbury, NY 11590; telephone 516-228-7329;  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-2021-0613; Project Identifier MCAI-2020-01431-T;
Amendment 39-21801; AD 2021-23-03]
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 cracking found
on a main landing gear (MLG) drag strut assembly. This AD requires a
records review to determine if an affected MLG drag strut assembly is
installed, repetitive detailed inspections for cracking of affected
strut assemblies, a one-time magnetic particle inspection for cracking,
and on-condition actions if necessary. The FAA is issuing this AD to
address the unsafe condition on these products.

DATES: This AD is effective December 6, 2021.

ADDRESSES:

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-
0613; 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: Aziz Ahmed, Aerospace Engineer,
Airframe and Propulsion Section, FAA, New York ACO Branch, 1600 Stewart
Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7329; 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-2020-43, dated October 21,
2020 (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-2021-0613.
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 August 3, 2021 (86 FR
41794). The NPRM was prompted by a report of cracking found on an MLG
drag strut assembly. The NPRM proposed to require a records review to
determine if an affected MLG drag strut assembly is installed,
repetitive detailed inspections for cracking of affected strut
assemblies, a one-time magnetic particle inspection for cracking, and
on-condition actions if necessary. The FAA is issuing this AD to
address cracking of the MLG drag strut assembly and possible failure
under compression loads during landing or ground operations, which
could result in asymmetric MLG configuration and potential 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.

Costs of Compliance

The FAA estimates that this AD will affect 34 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 11 work-hours x $85 per hour = to $935 Up $0 Up to $935 Up to $31,790

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
Cost on U.S. operators
Up to 10 work-hours x $85 per hour = Up to $850 * $ Up to $850 Up to $850

* The FAA has received no definitive data that would enable the agency to
provide parts cost estimates for the actions specified in this AD.

The FAA has included all known costs in its cost estimate.
According to the manufacturer, however, some or all of the costs of
this AD may be covered under warranty, thereby reducing the cost impact
on affected operators.

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: