[Federal Register Volume 89, Number 32 (Thursday, February 15, 2024)]
[Rules and Regulations]
[Pages 11713-11715]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-03081]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2023-0933; Project Identifier MCAI-2022-00554-T; 
Amendment 39-22666; AD 2024-02-02]
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: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain De Havilland Aircraft of Canada Limited Model DHC-8-401 and -
402 airplanes. This AD was prompted by reports that the saddle washer 
(radius filler) for the front and rear spar joints may have been 
incorrectly manufactured for several years. This AD requires inspecting 
the horizontal stabilizer to vertical joint for gaps and bending of the 
saddle washer and adjacent washers, and replacing parts if necessary. 
The FAA is issuing this AD to address the unsafe condition on these 
products.

DATES: This AD is effective March 21, 2024.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of March 21, 
2024.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2023-0933; 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, the mandatory continuing airworthiness 
information (MCAI), 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.
    Material Incorporated by Reference:
     For service information identified in this final rule, 
contact De Havilland Aircraft of Canada Limited, Dash 8 Series Customer 
Response Centre, 5800 Explorer Drive, Mississauga, Ontario, L4W 5K9, 
Canada; telephone 855-310-1013 or 647-277-5820; email 
dehavilland.com">thd@dehavilland.com; website dehavilland.com.
     You may view this service information at the FAA, 
Airworthiness Products Section, Operational Safety Branch, 2200 South 
216th Street, Des Moines, WA. For information on the availability of 
this material at the FAA, call 206-231-3195. It is also available at 
regulations.gov under Docket No. FAA-2023-0933.

FOR FURTHER INFORMATION CONTACT: Yaser Osman, Aviation Safety Engineer, 
FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-
228-7300; email [email protected].

SUPPLEMENTARY INFORMATION:

Background

    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-8-401 and -402 airplanes. The NPRM 
published in the Federal Register on April 19, 2023 (88 FR 24144). The 
NPRM was prompted by AD CF-2022-21, dated April 21, 2022, issued by 
Transport Canada, which is the aviation authority for Canada (referred 
to after this as the MCAI). The MCAI states that certain saddle washers 
for the front and rear spar joint may have been incorrectly 
manufactured for several years. Non-conforming saddle washers could 
potentially become deformed when installed, and lead to gaps at the 
horizontal stabilizer to vertical stabilizer joint, that would result 
in reduction of the pre-load at the joint.
    In the NPRM, the FAA proposed to require inspecting the horizontal 
stabilizer to vertical joint for gaps and bending of the saddle washer 
and adjacent washers, and replacing parts if necessary. The FAA is 
issuing this AD to address gapping and bending of the saddle washer 
that could have the potential to reduce the life of the bolt, which in 
turn could affect the structural integrity of the horizontal stabilizer 
to vertical stabilizer joint.
    You may examine the MCAI in the AD docket at regulations.gov under 
Docket No. FAA-2023-0933.

Discussion of Final Airworthiness Directive

Comments

    The FAA received a comment from the Air Line Pilots Association, 
International (ALPA). ALPA supported the NPRM without change.
    The FAA received additional comments from De Havilland Aircraft of 
Canada Limited. The following presents the comments received on the 
NPRM and the FAA's response to each comment.

Request To Refer to New Service Information

    De Havilland Aircraft of Canada Limited requested that the FAA 
revise the proposed AD to refer to De Havilland Aircraft of Canada 
Limited Service Bulletin 84-55-12, Revision B, dated April 20, 2023. De 
Havilland Aircraft of Canada Limited noted that the service information 
had been updated since the NPRM was released.
    The FAA agrees with the request. De Havilland Aircraft of Canada 
Limited Service Bulletin 84-55-12, Revision B, dated April 20, 2023, 
provides clarity on service information that may be used to do rework 
if there are gaps in the new radius fillers (saddle washers), and 
specifies an additional radius filler part number. The FAA has revised 
this AD to refer to De Havilland Aircraft of Canada Limited Service 
Bulletin 84-55-12, Revision B, dated April 20, 2023. The FAA has also 
revised paragraph (i) of this AD to provide credit for De Havilland 
Aircraft of Canada Limited Service Bulletin 84-55-12, Revision A, dated 
February 16, 2022.

Request To Revise Corrective Actions

    De Havilland Aircraft of Canada Limited requested that the FAA 
revise paragraph (h) of the proposed AD. The

[[Page 11714]]

commenter stated that De Havilland Aircraft of Canada Limited Service 
Bulletin 84-55-12, Revision B, dated April 20, 2023, includes 
instructions for reworking the new radius fillers that exhibit fouling 
conditions (gapping), and that the proposed AD should be amended to 
explain this.
    The FAA agrees to clarify. Paragraph (h) of this AD requires 
corrective actions (parts replacements) in accordance with Section 
3.B., Part B, of the Accomplishment Instructions of De Havilland 
Aircraft of Canada Limited Service Bulletin 84-55-12, Revision B, dated 
April 20, 2023. The rework the commenter mentioned is part of Section 
3.B., Part B, and is specified as part of the corrective actions if 
gapping is found after replacement of the radius filler. Therefore, 
that step is included as part of the requirements of paragraph (h) of 
this AD.

Request To Correct the Number of U.S. Registered Airplanes

    De Havilland Aircraft of Canada Limited requested that the FAA 
revise the cost of compliance section to correct the number of affected 
airplanes. The commenter stated that the number of aircraft on the U.S. 
registry is 49, not 400 as stated in the NPRM.
    The FAA agrees that the number of U.S. registered airplanes is less 
than that specified in the NPRM. After reviewing the FAA registry, the 
FAA has determined the correct number of affected airplanes is 54. The 
FAA has revised the Costs of Compliance section accordingly.

Conclusion

    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 this State of Design Authority, it 
has notified the FAA of the unsafe condition described in the MCAI 
referenced above. The FAA reviewed the relevant data, considered the 
comments received, and determined that air safety requires adopting 
this AD as proposed. Accordingly, the FAA is issuing this AD to address 
the unsafe condition on this product. Except for minor editorial 
changes, and any other changes described previously, this AD is adopted 
as proposed in the NPRM. None of the changes will increase the economic 
burden on any operator.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed De Havilland Aircraft of Canada Limited Service 
Bulletin 84-55-12, Revision B, dated April 20, 2023. This service 
information specifies procedures for a detailed visual inspection of 
the front and rear spar joints for signs of gapping or bending of the 
radius filler and/or adjacent washers, and depending on the inspection 
results, replacement of the saddle washer, adjacent washers, bolt, and 
barrel nut.
    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
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                                                                                    Cost per       Cost on U.S.
                          Labor cost                              Parts cost        product         operators
----------------------------------------------------------------------------------------------------------------
5 work-hours x $85 per hour = $425...........................              $0             $425          $22,950
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    The FAA estimates the following costs to do any necessary on-
condition action 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 this on-condition action:

                 Estimated Costs of On-Condition Actions
------------------------------------------------------------------------
                                                             Cost per
              Labor cost                   Parts cost        product
------------------------------------------------------------------------
2 work-hours x $85 per hour = $170....          $5,333           $5,503
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    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.

[[Page 11715]]

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

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

0
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]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive:

2024-02-02 De Havilland Aircraft of Canada Limited (Type Certificate 
Previously Held by Bombardier, Inc.): Amendment 39-22666; Docket No. 
FAA-2023-0933; Project Identifier MCAI-2022-00554-T.

(a) Effective Date

    This airworthiness directive (AD) is effective March 21, 2024.

(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-8-401 and 
-402 airplanes, certificated in any category, having serial numbers 
4001 and 4003 through 4633 inclusive.

(d) Subject

    Air Transport Association (ATA) of America Code: 55, 
Stabilizers.

(e) Unsafe Condition

    This AD was prompted by reports that the saddle washer (radius 
filler) for the front and rear spar joints may have been incorrectly 
manufactured for several years. The FAA is issuing this AD to 
address gaps and bending of the saddle washer that could have the 
potential to reduce the life of the bolt, which in turn could affect 
the structural integrity of the horizontal stabilizer to vertical 
stabilizer joint.

(f) Compliance

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

(g) Inspection

    Within 8,000 flight hours after the effective date of this AD, 
perform a detailed inspection for signs of gapping or bending of the 
saddle washers and adjacent washers in the front spar and rear spar 
horizontal/vertical stabilizer joint fitting in accordance with 
Section 3.B., Part A, of the Accomplishment Instructions of De 
Havilland Aircraft of Canada Limited Service Bulletin 84-55-12, 
Revision B, dated April 20, 2023.

(h) Corrective Actions

    If any gaps or bending of the washers are found during the 
inspection required by paragraph (g) of this AD, before further 
flight, replace the saddle washer, washers, PLI washer, bolt, and 
barrel nut, as applicable, in accordance with Section 3.B., Part B, 
of the Accomplishment Instructions of De Havilland Aircraft of 
Canada Limited Service Bulletin 84-55-12, Revision B, dated April 
20, 2023.

(i) Credit for Previous Actions

    This paragraph provides credit for actions required by 
paragraphs (g) and (h) of this AD, if those actions were performed 
before the effective date of this AD using De Havilland Aircraft of 
Canada Limited Service Bulletin 84-55-12, dated September 7, 2021; 
or De Havilland Aircraft of Canada Limited Service Bulletin 84-55-
12, Revision A, dated February 16, 2022.

(j) Additional AD Provisions

    The following provisions also apply to this AD:
    (1) Alternative Methods of Compliance (AMOCs): The Manager, 
International Validation 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 
International Validation Branch, send it to the attention of the 
person identified in paragraph (k)(2) of this AD. Information may be 
emailed to: [email protected]. 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, International 
Validation Branch, FAA; or Transport Canada; or De Havilland 
Aircraft of Canada Limited's Transport Canada Design Approval 
Organization (DAO). If approved by the DAO, the approval must 
include the DAO-authorized signature.

(k) Additional Information

    (1) Refer to Transport Canada AD CF-2022-21, dated April 21, 
2022, for related information. This Transport Canada AD may be found 
in the AD docket at regulations.gov under Docket No. FAA-2023-0933.
    (2) For more information about this AD, contact Yaser Osman, 
Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, 
Westbury, NY 11590; telephone 516-228-7300; email [email protected].
    (3) Service information identified in this AD that is not 
incorporated by reference is available at the addresses specified in 
paragraphs (l)(3) and (4) of this AD.

(l) 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-
55-12, Revision B, dated April 20, 2023.
    (ii) [Reserved]
    (3) For service information identified in this AD, contact De 
Havilland Aircraft of Canada Limited, Dash 8 Series Customer 
Response Centre, 5800 Explorer Drive, Mississauga, Ontario, L4W 5K9, 
Canada; telephone 855-310-1013 or 647-277-5820; email 
dehavilland.com">thd@dehavilland.com; website dehavilland.com.
    (4) You may view this service information at the FAA, 
Airworthiness Products Section, Operational Safety Branch, 2200 
South 216th Street, Des Moines, WA. For information on the 
availability of this material at the FAA, call 206-231-3195.
    (5) You may view this material at the National Archives and 
Records Administration (NARA). For information on the availability 
of this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email [email protected].

    Issued on January 24, 2024.
Victor Wicklund,
Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2024-03081 Filed 2-14-24; 8:45 am]
BILLING CODE 4910-13-P