
[Federal Register Volume 88, Number 152 (Wednesday, August 9, 2023)]
[Rules and Regulations]
[Pages 53761-53764]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-16964]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2023-1653; Project Identifier AD-2023-00899-A; 
Amendment 39-22519; AD 2023-15-07]
RIN 2120-AA64


Airworthiness Directives; Air Tractor, Inc. Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all 
Air Tractor, Inc. (Air Tractor) Model AT-802 and AT-802A airplanes that 
have Wipaire Supplemental Type Certificate (STC) No. SA01795CH 
installed. This AD was prompted by reports of cracks found in the 
forward horizontal stabilizer spar where the vertical finlets tie to 
the horizontal tail forward spar. This AD requires repetitively 
inspecting both the left and right forward horizontal stabilizer spars 
for cracks and replacing any forward horizontal stabilizer spar found 
cracked. This AD also requires reporting inspection results to the FAA. 
The FAA is issuing this AD to address the unsafe condition on these 
products.

DATES: This AD is effective August 9, 2023.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of August 9, 
2023.
    The FAA must receive comments on this AD by September 25, 2023.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to regulations.gov. Follow 
the instructions for submitting comments.

[[Page 53762]]

     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE, Washington, DC 20590.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2023-1653; 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 street address for Docket Operations is listed above.
    Material Incorporated by Reference:
     For service information identified in this final rule, 
contact Wipaire, Inc., 1700 Henry Ave., Fleming Field (KSGS), South St. 
Paul, MN 55075; phone: (651) 451-1205; email: 
wipaire.com">customerservice@wipaire.com; website: wipaire.com.
     You may view this service information at the FAA, 
Airworthiness Products Section, Operational Safety Branch, 901 Locust, 
Kansas City, MO 64106. For information on the availability of this 
material at the FAA, call (817) 222-5110. It is also available at 
regulations.gov under Docket No. FAA-2023-1653.

FOR FURTHER INFORMATION CONTACT: Tim Eichor, Aviation Safety Engineer, 
Central Certification Branch, FAA, 1801 S Airport Road, Wichita, KS 
67209; phone: (847) 294-7141; email: [email protected].

SUPPLEMENTARY INFORMATION: 

Comments Invited

    The FAA invites you to send any written data, views, or arguments 
about this final rule. Send your comments to an address listed under 
ADDRESSES. Include ``Docket No. FAA-2023-1653, Project Identifier AD-
2023-00899-A'' at the beginning of your comments. The most helpful 
comments reference a specific portion of the final rule, explain the 
reason for any recommended change, and include supporting data. The FAA 
will consider all comments received by the closing date and may amend 
this final rule because of those comments.
    Except for Confidential Business Information (CBI) as described in 
the following paragraph, and other information as described in 14 CFR 
11.35, the FAA will post all comments received, without change, to 
regulations.gov, including any personal information you provide. The 
agency will also post a report summarizing each substantive verbal 
contact received about this final rule.

Confidential Business Information

    CBI is commercial or financial information that is both customarily 
and actually treated as private by its owner. Under the Freedom of 
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public 
disclosure. If your comments responsive to this AD contain commercial 
or financial information that is customarily treated as private, that 
you actually treat as private, and that is relevant or responsive to 
this AD, it is important that you clearly designate the submitted 
comments as CBI. Please mark each page of your submission containing 
CBI as ``PROPIN.'' The FAA will treat such marked submissions as 
confidential under the FOIA, and they will not be placed in the public 
docket of this AD. Submissions containing CBI should be sent to Tim 
Eichor, Aviation Safety Engineer, Central Certification Branch, FAA, 
1801 South Airport Road, Wichita, KS 67209. Any commentary that the FAA 
receives which is not specifically designated as CBI will be placed in 
the public docket for this rulemaking.

Background

    During routine maintenance, an Air Tractor Model AT-802 airplane 
was found with a hairline crack in the flange of the right forward 
horizontal stabilizer spar. The airplane had STC No. SA01795CH 
installed and is used in fire-fighting missions, which can propagate 
crack growth more rapidly. Of the 144 Air Tractor Model AT-802 and AT-
802A airplanes that have this STC, 45 have been inspected, and 24 of 
those inspected had cracks found in at least one forward horizontal 
stabilizer spar. The cracking is in the forward horizontal stabilizer 
spar bend radius located at the STC finlet mounting locations.
    This condition, if not addressed, could result in structural 
failure of the horizontal tail with consequent loss of control of the 
airplane. The FAA is issuing this AD to address the unsafe condition on 
these products.

FAA's Determination

    The FAA is issuing this AD because the agency has determined the 
unsafe condition described previously is likely to exist or develop in 
other products of the same type design.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Wipaire, Inc. Service Letter 253, Revision B, 
dated July 27, 2023, which specifies procedures for inspecting the left 
and right forward horizontal stabilizer spars for cracks. 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 ADDRESSES.

AD Requirements

    This AD requires repetitively inspecting both the left and right 
forward horizontal stabilizer spars for cracks and replacing any 
forward horizontal stabilizer spar found cracked. This AD also requires 
reporting inspection results to the FAA.

Interim Action

    The FAA considers this AD to be an interim action. The STC design 
approval holder is working on a modification to the STC configurations 
to address this issue. The FAA may consider future rulemaking on this 
subject.

Justification for Immediate Adoption and Determination of the Effective 
Date

    Section 553(b)(3)(B) of the Administrative Procedure Act (APA) (5 
U.S.C. 551 et seq.) authorizes agencies to dispense with notice and 
comment procedures for rules when the agency, for ``good cause,'' finds 
that those procedures are ``impracticable, unnecessary, or contrary to 
the public interest.'' Under this section, an agency, upon finding good 
cause, may issue a final rule without providing notice and seeking 
comment prior to issuance. Further, section 553(d) of the APA 
authorizes agencies to make rules effective in less than thirty days, 
upon a finding of good cause.
    An unsafe condition exists that requires the immediate adoption of 
this AD without providing an opportunity for public comments prior to 
adoption. The FAA has found that the risk to the flying public 
justifies forgoing notice and comment prior to adoption of this rule 
because cracks in the forward horizontal stabilizer spars could lead to 
structural failure of the horizontal tail with consequent loss of 
control of the airplane. Airplanes with the affected STC installed are 
used in fire-fighting missions and put frequent high repetitive fatigue 
loads in this area at a high utilization rate. Based on the number of 
cracks found to date, a significant number of airplanes need to be 
inspected within 3 to 15 days depending on the configuration. This 
compliance time is shorter than the time necessary for the public to 
comment and for publication of the final rule.

[[Page 53763]]

    Accordingly, notice and opportunity for prior public comment are 
impracticable and contrary to the public interest pursuant to 5 U.S.C. 
553(b)(3)(B).
    In addition, the FAA finds that good cause exists pursuant to 5 
U.S.C. 553(d) for making this amendment effective in less than 30 days, 
for the same reasons the FAA found good cause to forgo notice and 
comment.

Regulatory Flexibility Act

    The requirements of the Regulatory Flexibility Act (RFA) do not 
apply when an agency finds good cause pursuant to 5 U.S.C. 553 to adopt 
a rule without prior notice and comment. Because FAA has determined 
that it has good cause to adopt this rule without prior notice and 
comment, RFA analysis is not required.

Costs of Compliance

    The FAA estimates that this AD affects 30 airplanes of U.S. 
registry.
    The FAA estimates the following costs to comply with this AD:

                                                 Estimated Costs
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            Action                Labor cost      Parts cost      Cost per product       Cost on U.S. operators
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Inspect forward horizontal     20 work-hours x            $0  $1,700 per inspection     $51,000 per inspection
 stabilizer spars.              $85 per hour =                 cycle.                    cycle.
                                $1,700.
Report inspection results....  1 work-hour x               0  85 per inspection cycle.  2,550 per inspection
                                $85 per hour =                                           cycle.
                                $85.
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    The FAA estimates the following costs to do any necessary 
replacements that would be required based on the results of the 
inspection. The agency has no way of determining the number of 
airplanes that might need this replacement:

                                               On-Condition Costs
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                                                                                                     Cost per
                    Action                                 Labor cost               Parts cost        product
----------------------------------------------------------------------------------------------------------------
Replace a cracked forward horizontal            40 work-hours x $85 per hour =            $1,325          $4,725
 stabilizer spar.                                $3,400.
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Paperwork Reduction Act

    A federal agency may not conduct or sponsor, and a person is not 
required to respond to, nor shall a person be subject to a penalty for 
failure to comply with a collection of information subject to the 
requirements of the Paperwork Reduction Act unless that collection of 
information displays a currently valid OMB Control Number. The OMB 
Control Number for this information collection is 2120-0056. Public 
reporting for this collection of information is estimated to be 
approximately 1 hour per response, including the time for reviewing 
instructions, searching existing data sources, gathering and 
maintaining the data needed, and completing and reviewing the 
collection of information. All responses to this collection of 
information are mandatory. Send comments regarding this burden estimate 
or any other aspect of this collection of information, including 
suggestions for reducing this burden to: Information Collection 
Clearance Officer, Federal Aviation Administration, 10101 Hillwood 
Parkway, Fort Worth, TX 76177-1524.

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, and
    (2) Will not affect intrastate aviation in Alaska.

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:

2023-15-07 Air Tractor, Inc.: Amendment 39-22519; Docket No. FAA-
2023-1653; Project Identifier AD-2023-00899-A.

(a) Effective Date

    This airworthiness directive (AD) is effective August 9, 2023.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Air Tractor, Inc. Model AT-802 and AT-802A 
airplanes, all serial numbers, certificated in any category, that

[[Page 53764]]

have Wipaire, Inc. Supplemental Type Certificate (STC) No. SA01795CH 
installed.

(d) Subject

    Joint Aircraft System Component (JASC) Code 5510, Horizontal 
Stabilizer Structure; 5511 Horizontal stabilizer, Spar/Rib; 5514, 
Horizontal Stabilizer Miscellaneous Structure; 5530, Vertical 
Stabilizer Structure.

(e) Unsafe Condition

    This AD was prompted by reports of cracks found in at least one 
forward horizontal stabilizer spar on 24 of the affected airplanes 
where the vertical finlets tie to the forward horizontal stabilizer 
spar. The FAA is issuing this AD to prevent structural failure of 
the forward horizontal stabilizer spars. The unsafe condition, if 
not addressed, could result in structural failure of the horizontal 
tail with consequent loss of control of the airplane.

(f) Compliance

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

(g) Required Actions

    (1) At the compliance times in paragraphs (g)(1)(i) through 
(iii) of this AD, as applicable, and thereafter at intervals not to 
exceed 200 hours time-in-service (TIS), inspect the left and right 
forward horizontal stabilizer spars for cracks in accordance with 
Steps 1 through 9 of the Work Instructions of Wipaire, Inc. Service 
Letter 253, Revision B, dated July 27, 2023.
    (i) For STC configuration 7D1-4399-01: Within 3 days or 24 hours 
TIS after the effective date of this AD or before the accumulation 
of 200 hours TIS since installation of STC No. SA01795CH, whichever 
occurs later.
    (ii) For STC configuration 7D1-4399-02: Within 5 days or 24 
hours TIS after the effective date of this AD or before the 
accumulation of 300 hours TIS since installation of STC No. 
SA01795CH, whichever occurs later.
    (iii) For STC configuration 7D1-4399-03: Within 15 days or 24 
hours TIS after the effective date of this AD or before the 
accumulation of 600 hours TIS since installation of STC No. 
SA01795CH, whichever occurs later.
    (2) If any crack is found in a forward horizontal stabilizer 
spar during any inspection required by paragraph (g)(1) of this AD, 
before further flight, replace the cracked forward horizontal 
stabilizer spar. Replacement of the cracked forward horizontal 
stabilizer spar starts the initial and repetitive inspections over.
    (3) Within 10 days after each inspection required by paragraph 
(g)(1) of this AD or within 10 days after the effective date of this 
AD, whichever occur later, report the following to the FAA at the 
address in paragraph (j)(1) of this AD. Report this information 
regardless of whether cracks are found.
    (i) Model, engine configuration (with horsepower limits), and 
propeller type;
    (ii) Serial number and N number;
    (iii) Total hours TIS on airframe;
    (iv) Total hours TIS operated with floats, if known;
    (v) STC configuration and total hours with STC installed;
    (vi) Crack location (right or left, upper/lower caps inboard/
outboard hole);
    (vii) Crack size;
    (viii) Photos of cracks found, if available; and
    (ix) Any additional operator/mechanic comments

(h) Credit for Previous Actions

    You may take credit for the initial inspection required by 
paragraph (g)(1) of this AD if, before the effective date of this 
AD, you complied with Wipaire, Inc. Service Letter 253, Revision A, 
dated April 5, 2023.

(i) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Central Certification 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 Branch, send it to the 
attention of the person identified in paragraph (j)(1) of this AD.
    (2) 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.

(j) Related Information

    (1) For more information about this AD, contact Tim Eichor, 
Aviation Safety Engineer, Central Certification Branch, FAA, 1801 S 
Airport Road, Wichita, KS 67209; phone: (847) 294-7141; email: 
[email protected].
    (2) 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 the AD specifies otherwise.
    (i) Wipaire, Inc. Service Letter 253, Revision B, dated July 27, 
2023.
    (ii) [Reserved]
    (3) For service information identified in this AD, contact 
Wipaire, Inc., 1700 Henry Ave, Fleming Field (KSGS), South St. Paul, 
MN 55075; phone: (651) 451-1205; email: wipaire.com">customerservice@wipaire.com; 
website: wipaire.com.
    (4) You may view this service information at the FAA, 
Airworthiness Products Section, Operational Safety Branch, 901 
Locust, Kansas City, MO 64106. For information on the availability 
of this material at the FAA, call (817) 222-5110.
    (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.

    Issued on July 28, 2023.
Ross Landes,
Deputy Director for Regulatory Operations, Compliance & Airworthiness 
Division, Aircraft Certification Service.
[FR Doc. 2023-16964 Filed 8-7-23; 11:15 am]
BILLING CODE 4910-13-P


