[Federal Register Volume 88, Number 94 (Tuesday, May 16, 2023)]
[Rules and Regulations]
[Pages 31148-31152]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-10333]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-1403; Project Identifier MCAI-2022-00122-T; 
Amendment 39-22408; AD 2023-07-06]
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 of corrosion on the 
horizontal stabilizer lower center skin panel, including a finding of 
corrosion where the skin thickness had been substantially reduced, 
which affected design margins. This AD requires inspecting the 
horizontal stabilizer lower center skin panel for corrosion, and 
reworking, repairing, or replacing the lower center skin panel if 
necessary. The FAA is issuing this AD to address the unsafe condition 
on these products.

DATES: This AD is effective June 20, 2023.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in this AD as of June 20, 
2023.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2022-1403; 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">[email protected]dehavilland.com; website dehavilland.com.

[[Page 31149]]

     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 at 
regulations.gov under Docket No. FAA-2022-1403.

FOR FURTHER INFORMATION CONTACT: Yaser Osman, Aerospace Engineer, 
Airframe and Propulsion Section, FAA, New York ACO Branch, 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 November 4, 2022 (87 FR 66619). 
The NPRM was prompted by AD CF-2022-02, dated January 28, 2022, issued 
by Transport Canada, which is the aviation authority for Canada 
(referred to after this as the MCAI). The MCAI states that there have 
been reports of corrosion on the horizontal stabilizer lower center 
skin panel, including a finding of corrosion where the skin thickness 
had been substantially reduced, affecting design margins. The root 
cause was found to be inconsistent chemical processing of the lower 
center skin panel, with missing anodizing layer and primer on some 
areas of the skin panel surface. A substantial reduction of skin panel 
thickness due to the effects of corrosion will compromise the 
structural integrity of the horizontal stabilizer.
    In the NPRM, the FAA proposed to require inspecting the horizontal 
stabilizer lower center skin panel for corrosion, and reworking, 
repairing, or replacing the lower center skin panel if necessary.
    The FAA is issuing this AD to address possible reduction of skin 
panel thickness due to the effects of corrosion, which could compromise 
the structural integrity of the horizontal stabilizer. You may examine 
the MCAI in the AD docket at regulations.gov under Docket No. FAA-2022-
1403.

Discussion of Final Airworthiness Directive

Comments

    The FAA received comments from Air Line Pilots Association, 
International (ALPA) who supported the NPRM without change.
    The FAA received additional comments from Horizon Air. The 
following presents the comment received on the NPRM and the FAA's 
response to the comment.

Request To Limit Certain Requirements

    Horizon Air requested that paragraph (g)(3)(i) of the proposed AD 
require only Section 3.B. (Procedure) of the Accomplishment 
Instructions of De Havilland Aircraft of Canada Limited Service 
Bulletin 84-55-11, dated February 16, 2021. Horizon Air stated that 
requiring the job set-up and close out sections restricts an operator's 
ability to perform other maintenance in conjunction with the 
incorporation of the service information. Horizon Air added that the 
job set-up and close out sections do not directly correct the unsafe 
conditions.
    The FAA agrees with the request to limit the requirements to 
simplify the procedure and allow the performance of other maintenance 
in conjunction with the required actions of this AD. Paragraph 
(g)(3)(i) of this AD has been changed to limit the requirements as 
requested.

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

    De Havilland Aircraft of Canada Limited has issued Service Bulletin 
84-55-05, Revision C, dated August 19, 2021. This service information 
describes procedures for inspecting the horizontal stabilizer lower 
center skin panel for corrosion, and, depending on the level of 
corrosion, reworking or repairing the horizontal stabilizer lower 
center skin panel.
    De Havilland Aircraft of Canada Limited has also issued Service 
Bulletin 84-55-11, dated February 16, 2021. This service information 
describes procedures for replacing the horizontal stabilizer lower 
center skin panel.
    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 56 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
----------------------------------------------------------------------------------------------------------------
108 work-hours x $85 per hour = $9,180.......................              $0           $9,180         $514,080
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    The FAA estimates the following costs to do any necessary on-
condition replacements 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 replacement:

[[Page 31150]]



                 Estimated Costs of On-Condition Actions
------------------------------------------------------------------------
                                                             Cost per
              Labor cost                   Parts cost        product
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108 work-hours x $85 per hour = $9,180         $21,449          $30,629
------------------------------------------------------------------------

    The FAA has received no definitive data on which to base the cost 
estimates for the on-condition repairs or rework 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.

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:

2023-07-06 De Havilland Aircraft of Canada Limited (Type Certificate 
Previously Held by Bombardier, Inc.): Amendment 39-22408; Docket No. 
FAA-2022-1403; Project Identifier MCAI-2022-00122-T.

(a) Effective Date

    This airworthiness directive (AD) is effective June 20, 2023.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to De Havilland Aircraft of Canada Limited Model 
DHC-8-401 and -402 airplanes, certificated in any category, having 
serial numbers 4001 and 4003 through 4549 inclusive.

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by reports of corrosion on the horizontal 
stabilizer lower center skin panel, including a finding of corrosion 
where the skin thickness had been substantially reduced, which 
affected design margins. The FAA is issuing this AD to address 
possible substantial reduction of skin panel thickness due to the 
effects of corrosion, which could compromise the structural 
integrity of the horizontal stabilizer.

(f) Compliance

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

(g) Inspection and Corrective Actions

    (1) Within 8,000 flight hours or 48 months, whichever occurs 
first, after the effective date of this AD: Inspect the horizontal 
stabilizer lower center skin panel for corrosion in accordance with 
Section 3.B. Part A of the Accomplishment Instructions of De 
Havilland Aircraft of Canada Limited Service Bulletin 84-55-05 
Revision C, dated August 19, 2021. If any corrosion is found, before 
further flight, do the applicable actions specified in paragraph 
(g)(2) or (3) of this AD.
    (2) If the corrosion is within the allowable repair limits as 
specified in Figure 5 Detail C of De Havilland Aircraft of Canada 
Limited Service Bulletin 84-55-05 Revision C, dated August 19, 2021, 
perform the corrosion rework in accordance with Section 3.B. Part B 
of the Accomplishment Instructions of De Havilland Aircraft of 
Canada Limited Service Bulletin 84-55-05 Revision C, dated August 
19, 2021.
    (3) If the corrosion is beyond the allowable repair limits as 
specified in Figure 5 Detail C of De Havilland Aircraft of Canada 
Limited Service Bulletin 84-55-05 Revision C, dated August 19, 2021, 
accomplish the action specified in paragraph (g)(3)(i) or (ii) of 
this AD.
    (i) Replace the existing horizontal stabilizer lower center skin 
panel in accordance with Section 3.B. Procedure of the 
Accomplishment Instructions of De Havilland Aircraft of Canada 
Limited Service Bulletin 84-55-11, dated February 16, 2021.
    (ii) Obtain and follow repair instructions using a method 
approved by the Manager, New York ACO 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.

(h) Credit for Previous Actions

    (1) This paragraph provides credit for actions required by 
paragraphs (g)(1) and (2) of this AD, if those actions were 
performed before the effective date of this AD using De Havilland 
Aircraft of Canada Limited Service Bulletin 84-55-05, Initial Issue, 
dated January 12, 2016; De Havilland Aircraft of Canada Limited 
Service Bulletin 84-55-05, Revision A, dated June 3, 2016; or De 
Havilland Aircraft of Canada Limited Service Bulletin 84-55-05, 
Revision B, dated February 26, 2021.
    (2) This paragraph provides credit for the actions required by 
paragraph (g)(2) or (3) of this AD, if those actions were performed 
before the effective date of this AD using any of the repair 
drawings (RDs) specified in figure 1 to paragraph (h) of this AD.

Figure 1 to Paragraph (h)--Repair Drawings

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[GRAPHIC] [TIFF OMITTED] TR16MY23.000

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(i) Additional 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. 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; 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.

(j) Additional Information

    (1) Refer to Transport Canada AD CF-2022-02, dated January 28, 
2022, for related information. This Transport Canada AD may be found 
in the AD docket at regulations.gov under Docket No. FAA-2022-1403.
    (2) For more information about this AD, contact Yaser Osman, 
Aerospace Engineer, Airframe and Propulsion Section, FAA, New York 
ACO Branch, 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 (k)(3) and (4) of this AD.

(k) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference 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-
55-05, Revision C, dated August 19, 2021.
    (ii) De Havilland Aircraft of Canada Limited Service Bulletin 
84-55-11, dated February 16, 2021.
    (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">[email protected]dehavilland.com; website dehavilland.com.
    (4) 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.
    (5) You may view this service information that is incorporated 
by reference at the National Archives and Records Administration 
(NARA). For information on the availability of this material at 
NARA, email [email protected], or go to: www.archives.gov/federal-register/cfr/ibr-locations.html.


[[Page 31152]]


    Issued on April 8, 2023.
Christina Underwood,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2023-10333 Filed 5-15-23; 8:45 am]
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