[Federal Register Volume 90, Number 220 (Tuesday, November 18, 2025)]
[Proposed Rules]
[Pages 51613-51620]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-20085]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-3438; Project Identifier AD-2025-01163-A]
RIN 2120-AA64
Airworthiness Directives; Twin Commander Aircraft LLC Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
for all Twin Commander Aircraft LLC (Twin Commander) Model 685, 690,
690A, 690B, 690C, 690D, 695, and 695A airplanes. This proposed AD was
prompted by reports of fatigue cracking affecting structural components
within the fuselage and empennage structure. This proposed AD would
require inspecting certain structural components within the fuselage
and vertical stabilizer for any evidence of cracks, corrosion, or loose
hardware, and inspecting the working fasteners at the diagonal braces
of fuselage station (FS) 386 for cracks, elongation, or deformation;
and depending on the results of the inspections, replacing with new
parts or used parts or repairing, as applicable; and reporting
inspection results to the FAA. The FAA is proposing this AD to address
the unsafe condition on these products.
DATES: The FAA must receive comments on this proposed AD by January 2,
2026.
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.
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-2025-3438; 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 NPRM, any comments received, and other
information. The street address for Docket Operations is listed above.
FOR FURTHER INFORMATION CONTACT: Lekebis Russell, Aviation Safety
Engineer, FAA, 1701 Columbia Avenue, College Park, GA 30337; phone:
(404) 474-5510; email: [email protected].
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments using a method listed
under the ADDRESSES section. Include ``Docket No. FAA-2025-3438;
Project Identifier AD-2025-01163-A'' at the beginning of your comments.
The most helpful comments reference a specific portion of the proposal,
explain the reason for any recommended change, and include supporting
data. The FAA
[[Page 51614]]
will consider all comments received by the closing date and may revise
this proposal 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 NPRM.
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 NPRM 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 NPRM, 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 NPRM. Submissions containing CBI should be sent to
Lekebis Russell, Aviation Safety Engineer, FAA, 1701 Columbia Avenue,
College Park, GA 30337. Any commentary that the FAA receives which is
not specifically designated as CBI will be placed in the public docket
for this rulemaking.
Background
The FAA received reports of fatigue cracking throughout the
fuselage and vertical stabilizer's structural components on Twin
Commander Model 685, 690, 690A, 690B, 690C, 690D, 695, and 695A
airplanes. The fatigue cracking was found in areas with insufficient
access for inspections, which led to undetected crack development.
Specifically, cracking was observed at FS 409, the vertical
stabilizer's aft spar, the horizontal stabilizer's forward spar, and
the vertical stabilizer skin.
AD 95-13-02, Amendment 39-9283 (60 FR 32583, June 23, 1995) (AD 95-
13-02) was issued to address cracking in the vertical stabilizer. This
AD requires initially inspecting the vertical stabilizer for cracks,
modifying any cracked vertical stabilizer, and, if not cracked, either
repetitively inspecting or modifying the vertical stabilizer, and
allowed for terminating action through modification or repair. Since
the issuance of AD 95-13-02, continued cracking has been observed at FS
409. These findings show that previously implemented modifications in
AD 95-13-02 did not provide an effective terminating action, along with
the detection of additional cracking at FS 386 and FS 429 during later
inspections. FS 386 and FS 429, where cracks were recently found, were
not part of the inspections required by AD 95-13-02. Therefore, this
proposed AD, while not superseding AD 95-13-02, addresses continued
cracking in FS 409, including areas adjacent to prior repairs, by
requiring inspections around repaired members, thereby complementing
the ongoing requirements of AD 95-13-02.
The FAA is proposing this AD to prevent the failure of the aft
fuselage or empennage structural members. The unsafe conditions, if not
addressed, could result in structural failure of the empennage, which
could lead to loss of control of the airplane.
FAA's Determination
The FAA is issuing this NPRM after determining that the unsafe
condition described previously is likely to exist or develop on other
products of the same type design.
Proposed AD Requirements in This NPRM
This proposed AD would require inspecting certain structural
components within the fuselage and vertical stabilizer for any evidence
of cracks, corrosion, or loose hardware, and inspecting the working
fasteners at the diagonal braces of FS 386 for cracks, elongation, or
deformation; and depending on the results of the inspections, replacing
with new parts or used parts or repairing, as applicable. This proposed
AD would also require reporting the inspection results to the FAA.
Interim Action
The FAA considers that this proposed AD would be an interim action.
An investigation is ongoing, and the final corrective action has not
yet been determined. Once corrective action has been determined, the
FAA may consider additional rulemaking action.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 589 airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed
AD:
Estimated Costs
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Cost per Cost on U.S.
Action Labor cost Parts cost product operators
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Perform detailed visual inspection FS 60 work-hours x $85 per $0 $5,100 $3,003,900
386, 409, 429, and vertical stabilizer. hour = $5,100.
Perform general visual inspection of 30 work-hours x $85 per 0 2,550 1,501,950
empennage structure. hour = $2,550.
Report inspection findings............... 1 work-hour x $85 per hour 0 85 50,065
= $85.
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The extent of the fatigue cracking within the fuselage or empennage
structural components may vary significantly from airplane to airplane.
The FAA has no way to determine how much damage may be found on each
airplane, the extent of the damage, the cost to repair the damaged
areas (or replace the part, if needed), or the number of airplanes that
might require repair or replacement.
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
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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
The FAA determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD would 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 this proposed
regulation:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Would not affect intrastate aviation in Alaska, and
(3) Would 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 Proposed Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 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:
Twin Commander Aircraft LLC: Docket No. FAA-2025-3438; Project
Identifier AD-2025-01163-A.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive
(AD) by January 2, 2026.
(b) Affected ADs
None.
(c) Applicability
This AD applies to Twin Commander Aircraft LLC Model 685, 690,
690A, 690B, 690C, 690D, 695, and 695A airplanes, all serial numbers,
certificated in any category.
(d) Subject
Joint Aircraft System Component (JASC) Code 5500, Empennage
Structure.
(e) Unsafe Condition
This AD was prompted by reports of fatigue cracking affecting
structural components within the fuselage and empennage structure.
The FAA is issuing this AD to prevent the failure of the aft
fuselage or empennage structural members. The unsafe condition, if
not addressed, could result in structural failure of the empennage,
which could lead to loss of control of the airplane.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Required Actions
(1) Within 50 hours time-in-service (TIS) after the effective
date of this AD, thoroughly clean the empennage interior structure
and perform the inspections in paragraphs (g)(1)(i), (ii), and (iii)
of this AD.
(i) A detailed visual inspection for cracks, corrosion, or loose
hardware, using at least 10x magnification, and the figures provided
in appendix 1 of this AD, at the locations identified in paragraphs
(g)(1)(i)(A) through (P).
(A) Fuselage Station (FS) 386: Frame Web at each corner radius
(B) FS 386: Horizontal Brace Joggles
(C) FS 386: Frame Upper Cable Cutouts
(D) FS 386: Diagonal Braces
(E) FS 409: Horizontal Stabilizer Front Spar
(F) FS 409: Vertical Stabilizer Spar Web
(G) FS 409: Frame Web at each corner fillet radius
(H) FS 409: Frame Web below horizontal stabilizer spar
(I) FS 409: Frame Tangs attaching fuselage skin
(J) FS 409: Exterior Fuselage Skin at cutouts corners
(K) FS 409: Exterior Fuselage Skin at frame tang attachment
(L) FS 409: Vertical Stabilizer Spar Web Forward and Aft Clips
(M) FS 429: Aft Frame Channel and Web
(N) FS 429: Forward Channel attached to frame
(O) Vertical Stabilizer Skin: Repair Skin Doubler
(P) Vertical Stabilizer: Mid Spar Flange
(ii) A detailed visual inspection for cracks, elongation, or
deformation of the working fasteners at location (D) FS 386 diagonal
braces, using at least 10x magnification.
(iii) A general visual inspection of areas adjacent to the
structures in paragraphs (g)(1)(i)(A) through (P) of this AD within
the empennage structure for any evidence of cracks, corrosion, or
loose hardware. Additional access or teardown is not required for
this inspection.
(iv) For inspections required by paragraph (g)(1)(i), (ii), and
(iii) of this AD, it is satisfactory to inspect the immediate area
adjacent to previously installed repairs for any cracking, or
corrosion, or loose hardware. Repairs or modifications previously
installed will not be required to be removed from the airplane
unless damage is found.
Note 1 to paragraph (g)(1): Paragraph 5-18, Visual Inspection
Procedures, of Chapter 5, Nondestructive Inspection (NDI), Section
2, Visual Inspection, of FAA Advisory Circular 43.13-1B,
``Acceptable Methods, Techniques, and Practices--Aircraft Inspection
and Repair,'' Change 1, dated September 8, 1998; with Editorial
Update dated September 27, 2001, provides guidance on performing
visual inspections.
(2) If, during the inspections required by paragraph (g)(1)(i),
(ii), or (iii)of this AD, any evidence of cracks, corrosion, or
loose hardware is found at FS 386, or FS 409, or FS 429 or the
vertical stabilizer or cracks, elongation, or deformation are found
to the holes of the working fasteners at the diagonal braces of FS
386, before further flight, replace with new parts with zero hours
TIS or used parts that have been inspected per paragraphs (g)(1)(i),
(ii), and (iii) of this AD and found to be free of cracks corrosion,
or loose hardware, or repair using a method approved by the Manager,
East Certification Branch, FAA. For a repair method to be approved
by the Manager, East Certification Branch, FAA as required by this
paragraph, the Manager's approval letter must specifically refer to
this AD.
Note 2 to paragraph (g)(2): If a repair in FS 409 is necessary,
then an alternative method of compliance would also be necessary in
this area for those doing repetitive inspections in accordance with
AD 95-13-02; Amendment 39-9283; (87 FR 32583; June 23, 1995) per 14
CFR 39.17. This would include if a repair was necessary that was
different than that required by AD 95-13-02.
[[Page 51616]]
(h) Reporting Requirement
Within 30 days after performing the inspections required by
paragraphs (g)(1)(i), (ii), and (iii) of this AD or within 30 days
after the effective date of this AD, whichever occurs later, report
the results of the inspections, including no findings, to the FAA at
[email protected]. The report must include the following:
(1) The name and address of owner;
(2) The date of the inspection;
(3) The name, address, telephone number, and email address of
person submitting the report;
(4) The airplane serial number, registration number, total
flight hours, flight hours during the last 12 months, airplane usage
(e.g., 14 CFR part 91/135--general, forest service, fire attack
roles, low aerial survey, etc.);
(5) The flight hours of any usage under forest service, fire
attack roles, or aerial survey (nonstandard usage).
(6) A description of cracks, corrosion, or loose hardware of the
fuselage structure or vertical stabilizer or cracks, elongation, or
deformation of the working fasteners at the diagonal braces of FS
386. Include affected structure, dimensions, including length and
location.
(i) Alternative Methods of Compliance (AMOCs)
(1) The Manager, East 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 East Certification Branch, send it to
the attention of the person identified in paragraph (j)(1) of this
AD and email to: [email protected].
(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) Additional Information
(1) For more information about this AD, contact Lekebis Russell,
Aviation Safety Engineer, FAA, 1701 Columbia Avenue, College Park,
GA 30337; phone: (404) 474-5510; email: [email protected].
(2) FAA Advisory Circular 43.13-1B, ``Acceptable Methods,
Techniques, and Practices--Aircraft Inspection and Repair,'' Change
1, dated September 8, 1998; with Editorial Update dated September
27, 2001, may be found at drs.faa.gov.
(k) Material Incorporated by Reference
None.
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Appendix 1 to Docket FAA-2025-3438
[GRAPHIC] [TIFF OMITTED] TP18NO25.029
Figure 1 to Appendix 1
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Appendix 1 to Docket FAA-2025-3438
[GRAPHIC] [TIFF OMITTED] TP18NO25.030
Figure 2 to Appendix 1
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Appendix 1 to Docket FAA-2025-3438
[GRAPHIC] [TIFF OMITTED] TP18NO25.031
Figure 3 to Appendix 1
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Appendix 1 to Docket FAA-2025-3438
[GRAPHIC] [TIFF OMITTED] TP18NO25.032
Figure 4 to Appendix 1
Issued on November 13, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2025-20085 Filed 11-17-25; 8:45 am]
BILLING CODE 4910-13-C