Airworthiness Directives; Textron Aviation Inc. Airplanes
The FAA proposes to adopt a new airworthiness directive (AD) for certain Textron Aviation, Inc., Model 408 airplanes. This proposed AD was prompted by the manufacturer's revisio...
The FAA proposes to adopt a new airworthiness directive (AD) for certain Textron Aviation, Inc., Model 408 airplanes. This proposed AD was prompted by the manufacturer's revision of the aircraft maintenance manual (AMM) to add a detailed inspection for the horizontal stabilizer spar, and change the airplane serial effectivity for the vertical stabilizer spar detailed inspection. This proposed AD would require revising the Airworthiness Limitations Section (ALS) of the existing AMM or instructions for continued airworthiness (ICA) and the existing approved maintenance or inspection program, as applicable. 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 June 15, 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-2026-3870; 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.
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-2026-3870; Project Identifier AD-2025-01364-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,
( printed page 23024)
and include supporting data. The FAA 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 Soban Saeed, Aviation Safety Engineer, 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
The FAA received a report from Textron Aviation, Inc, that an undetected crack could develop in the horizontal and vertical stabilizers forward and aft spars on certain Model 408 airplanes due to a quality escape from the supplier during manufacturing. As a result, Textron Aviation, Inc. issued revised limitations to the existing Model 408 AMM inspection program that require addition of a horizontal stabilizer spar detailed inspection and a revision to the airplane serial effectivity for the vertical stabilizer spar detailed inspection. The FAA is proposing this AD to detect and address cracks in the horizontal and vertical stabilizers forward and aft spars. The unsafe condition, if not addressed, could result in reduced structural integrity of the airplane or reduced controllability of the airplane with possible 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 revising the ALS of the existing AMM or ICA and the existing approved maintenance or inspection program, as applicable, by incorporating the actions and associated thresholds and intervals specified in table 1 to paragraph (g) of this proposed AD.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would affect 28 airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed AD:
Estimated Costs
Action
Labor cost
Parts cost
Cost per
product
Cost on U.S. operators
Revise the ALS
1 work-hour × $85 per hour = $85
$0
$85
$2,380
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:
(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.
This AD was prompted by the manufacturer's revision of the aircraft maintenance manual (AMM) to introduce a detailed inspection for the horizontal stabilizer spar, and change the airplane serial effectivity for the vertical stabilizer spar detailed inspection. The FAA is issuing this AD to detect and address cracks in the horizontal and vertical stabilizers forward and aft spars. The unsafe condition, if not addressed, could result in reduced structural integrity of the airplane or reduced controllability of the airplane with possible loss of control of the airplane.
(f) Compliance
Comply with this AD within the compliance times specified, unless already done.
Within 150 hours time-in-service or 12 months after the effective date of this AD, whichever occurs first: Revise the ALS of the existing AMM or instructions for continued airworthiness and the existing approved maintenance or inspection program, as applicable, by incorporating the information identified in table 1 to paragraph (g) of this AD.
Table 1 to Paragraph
(g)
—Revised Model 408 Airworthiness Limitation Tasks
Task No.
Task title
Interval
Inspection
document
Zone
Serial effectivity
55-10-00-221
Horizontal Stabilizer Spar Detailed Inspection
1600 flight hours
4-12-MB
351, 352
-0012 through -0040.
55-30-00-221
Vertical Stabilizer Spar Detailed Inspection
1600 flight hours
4-12-MB
341, 342, 343
-0012 through -0051.
Note 1 to paragraph (g):
Additional guidance for accomplishing the actions required by this AD can be found in Textron Aviation Service Letter SL408-04-01, dated December 8, 2025.
(h) Provisions for Alternative Actions and Intervals
After the action required by paragraph (g) of this AD has been performed, no alternative actions and associated thresholds and intervals are allowed unless they are approved as specified in the provisions of paragraph (i) of this AD.
(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 Central Certification Branch, send it to the attention of the person identified in paragraph (j)(1) of this AD and email to:
AMOC@faa.gov.
(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 Soban Saeed, Aviation Safety Engineer, FAA, 1801 South Airport Road, Wichita, KS 67209; phone: (316) 946-4123; email:
CCB-COS@faa.gov.
(2) For material identified in this AD that is not incorporated by reference, contact Textron Aviation Inc., P.O. Box 7706, Wichita, KS 67277; phone: (316) 517-6215; email:
citationpubs@txtav.com;
website:
ww2.txtav.com/technicalpublications/.