Quick Answers
What does FAA AD 2026-15-05 require for King Air 350 operators?
FAA AD 2026-15-05, effective August 10, 2026, requires operators of Textron B300 and B300C airplanes operating at 16,500 lb MTOW to revise their airworthiness limitations to incorporate corrected wing spar inspection intervals. The previous intervals were incorrect for heavy-weight aircraft. Some aircraft are already past the corrected intervals.
Why did the FAA issue an emergency AD for King Air 350 wing inspections?
The manufacturer’s ALM contained incorrect wing inspection intervals for King Air 350 aircraft operating at 16,500 lb MTOW. The heavier weight class accumulates higher wing loads, requiring shorter inspection intervals. FAA data confirmed some aircraft were already past the corrected intervals, creating an immediate risk of undetected wing spar cracks and wing separation.
Quick Compliance Summary
| Regulatory body | Federal Aviation Administration (FAA) |
| AD number | 2026-15-05 — Amendment 39-23417 |
| Docket | FAA-2026-7223 |
| Aircraft affected | Certain Textron Aviation Model B300 and B300C airplanes certified to or operating at 16,500 lb MTOW |
| Issue | The manufacturer’s ALM contained incorrect wing inspection intervals for heavy-weight aircraft. Some aircraft are already past the corrected intervals |
| Required action | Revise the Airworthiness Limitations Section of the AMM or ICA to incorporate corrected wing inspection intervals and component replacement schedules |
| Compliance deadline | August 10, 2026 — but compliance times vary by total time-in-service. Aircraft above 7,401 hours must comply within 25 hours TIS or 30 days |
| US fleet affected | 113 airplanes |
| Rulemaking type | Final rule; request for comments — good-cause exception |
| Source | Federal Register Vol. 91, No. 142, July 24, 2026 — FR Doc 2026-15006 |
Who Should Read This
This update is directly relevant to:
- Directors of Maintenance for King Air 350 operators
- Continuing Airworthiness Managers (CAMs)
- Part 135 operators using B300/B300C for charter, air ambulance, or special missions
- Part 91 owner-operators of heavy-weight King Air 350 aircraft
- Part 145 MRO organizations with King Air maintenance capability
- Military and government fleet managers operating modified B300 variants
If your King Air 350 is certified to or operating at 16,500 lb MTOW, this AD requires immediate attention. The FAA bypassed normal rulemaking because some aircraft are already past the corrected inspection intervals.
At a Glance
| Item | Details |
|---|---|
| AD Number | 2026-15-05 |
| Amendment | 39-23417 |
| Docket | FAA-2026-7223 |
| JASC Code | 5700 — Wing Structure |
| Aircraft | Textron B300 and B300C |
| Weight condition | Certified to or operating at 16,500 lb MTOW |
| Effective Date | August 10, 2026 |
| Unsafe condition | Undetected cracks in the wing spar or wing supporting structure → wing separation from fuselage in flight |
| Root cause | Incorrect wing inspection intervals in the manufacturer’s ALM for heavy-weight aircraft |
| US fleet affected | 113 airplanes |
| Cost per aircraft | $85 (1 work-hour) |
| Rulemaking type | Good-cause exception — some aircraft already past corrected intervals |
| Comment deadline | September 8, 2026 |
What Changed
The FAA published AD 2026-15-05 on July 24, 2026. It is effective August 10, 2026.
The FAA invoked the good-cause exception to bypass normal notice-and-comment rulemaking. The reason is stark: current FAA data indicate that a number of airplanes are already past the revised inspection intervals.
The problem originated with Textron. Textron notified the FAA that the existing Airworthiness Limitations Manual (ALM) for the B300 and B300C contained incorrect wing inspection intervals for airplanes certified to or operating at 16,500 lb MTOW.
The ALM did not differentiate between aircraft operating at 15,000 lb MTOW and those operating at 16,500 lb MTOW. A heavier aircraft accumulates higher wing loads per flight hour. The wing inspection intervals appropriate for a 15,000 lb airplane are not appropriate for one operating at 16,500 lb.
Textron has now revised the Structural Inspection and Repair Manual (SIRM) and ALM to separate the wing inspection criteria between the two weight categories. The FAA is mandating incorporation of the corrected intervals.
Why It Matters
The unsafe condition is the most severe in the entire AD series for this aircraft type.
Undetected cracks in the wing spar or wing supporting structure could result in reduced structural integrity and consequent wing separation from the fuselage in flight.
Wing separation is a catastrophic, unrecoverable failure mode.
The root cause makes this particularly urgent. This is not a newly discovered defect or an in-service event. This is a documentation error that has been in the ALM for an undetermined period. Aircraft operating at 16,500 lb MTOW have been flying under inspection intervals that were not validated for their weight class.
The FAA’s good-cause finding is explicit: the risk to the flying public justifies immediate action because some aircraft are already overdue for inspections they did not know they needed.
Who Is Affected — Weight Matters
This AD applies only to B300 and B300C airplanes that are certified to or operating at 16,500 lb MTOW.
Not all King Air 350 aircraft operate at that weight. The standard B300 is certificated at 15,000 lb MTOW. The 16,500 lb MTOW applies to aircraft with specific modification kits installed:
| Kit | Aircraft | Serial numbers |
|---|---|---|
| Kit 130-4402 (heavy weight) | Model B300 | FL-91, FL-381, FL-383, FL-387, FL-391 and on |
| Kit 130-4030 (heavy weight / non-extended range) | Model B300 and B300C | FL-381, FL-383 and on; FM-12 and on |
| Kit 130-4014 (increased gross weight with extended-range fuel tank) | Model B300 | FL-1 and on; FM-1 and on |
Exception: Aircraft that have had a wing evaluation performed by Textron Aviation Special Missions and been issued a serial-number-specific Aircraft Limitations Manual and SIRM supplement are excluded.
If you are unsure whether your aircraft operates at 16,500 lb MTOW, check for the presence of Kit 130-4402, 130-4030, or 130-4014. If any of these kits is installed, this AD applies.
Required Action — Three Compliance Groups by Total Time
The compliance time depends on how many total hours the aircraft has accumulated. Aircraft with more hours face shorter compliance windows because they are more likely to be past the corrected inspection intervals already.
Group 1 — Aircraft with 3,800 hours TTIS or less: Comply before accumulating 3,800 hours TTIS, or within 25 hours TIS or 30 days after August 10, 2026 — whichever occurs later.
Group 2 — Aircraft with 3,801 to 7,400 hours TTIS: Comply within 200 hours TIS or 6 months after August 10, 2026 — whichever occurs first.
Group 3 — Aircraft with more than 7,401 hours TTIS: Comply within 25 hours TIS or 30 days after August 10, 2026 — whichever occurs first. This is the tightest compliance window.
The required action for all three groups is the same. Revise the Airworthiness Limitations Section of the existing AMM or ICA and the existing approved maintenance or inspection program to incorporate the corrected inspection intervals and component replacement schedules specified in Textron Mandatory Service Letter MTL-57-04, Revision 1, dated March 27, 2025.
The Corrected Inspection Intervals
The revised intervals for 16,500 lb MTOW aircraft are materially different from the 15,000 lb intervals previously applied. Key items from the compliance table:
| Component | Interval for 16,500 lb MTOW aircraft |
|---|---|
| Wing to fuselage attach angles (early S/Ns without Kit 101-1202-0001) | Replace every 2,500 hours |
| Wing to fuselage attach angles (later S/Ns or with Kit 101-1202-0001) | Replace every 29,200 hours |
| Outboard wing structure (early S/Ns without upgraded spar caps) | Replace every 6,500 hours |
| Wing centre section (later S/Ns or with Kit 101-1200-0001) | Life not limited — subject to SIRM and AMM inspection programme adherence |
| Outboard wing structure (later S/Ns or with upgraded spar caps) | Life not limited — subject to SIRM and AMM inspection programme adherence |
The 2,500-hour replacement interval for wing-to-fuselage attach angles on early-serial-number aircraft is the most operationally significant. An aircraft accumulating 500–700 hours per year would reach this interval in 3.5–5 years. Aircraft already past 2,500 hours TTIS are overdue.
Operational Impact
The FAA’s cost estimate is modest — $85 per aircraft (1 work-hour at $85/hour) for the ALS revision itself. There are no parts costs for the revision action.
The real cost is downstream. Once the corrected intervals are incorporated, some aircraft will be found to be past their revised inspection or replacement thresholds. Those aircraft will require immediate inspection or component replacement before further flight.
For high-time B300/B300C aircraft operating at 16,500 lb MTOW — particularly those above 7,401 hours TTIS — the 25-hour or 30-day compliance window is tight. Confirm your total time-in-service and kit installation status today. Do not wait until August 10.
For operators with mixed-weight King Air 350 fleets, confirm which aircraft have the heavy-weight kits installed. Only those aircraft are affected by this AD. Standard 15,000 lb MTOW aircraft are not in scope.
Key Dates
| Event | Date |
|---|---|
| Textron MSL MTL-57-04, Revision 1 published | March 27, 2025 |
| Textron ALM Revision G0 published | April 29, 2026 |
| FAA AD 2026-15-05 published | July 24, 2026 |
| AD effective date | August 10, 2026 |
| Comment deadline | September 8, 2026 |
Source Documents
- Federal Register Vol. 91, No. 142, July 24, 2026 — FR Doc 2026-15006
- Textron Mandatory Service Letter MTL-57-04, Revision 1, March 27, 2025 — contact Textron at teamturboprop@txtav.com or (316) 517-9355
- Textron Super King Air B300/B300C Airworthiness Limitations Manual 130-590031-211G, Revision G0, April 29, 2026
- AD Docket: regulations.gov, Docket No. FAA-2026-7223
- FAA contact: Soban Saeed — CCB-COS@faa.gov, (316) 946-4123
FAQ
Does this AD apply to all King Air 350 aircraft?
No. It applies only to B300 and B300C airplanes certified to or operating at 16,500 lb MTOW — those with Kit 130-4402, 130-4030, or 130-4014 installed. Standard 15,000 lb MTOW aircraft are not affected.
Why did the FAA bypass normal rulemaking?
The FAA found that some aircraft are already past the corrected inspection intervals. The risk of undetected wing spar cracks — and the potential for wing separation — justified immediate action without the standard NPRM process.
What if my aircraft is already past 2,500 hours and has early-serial-number wing-to-fuselage attach angles?
You may already be past the corrected replacement interval. Contact Textron and your CAMO immediately to determine the status of your wing-to-fuselage attach angles and schedule replacement before further flight.
What is the difference between the 15,000 lb and 16,500 lb inspection intervals?
The 16,500 lb MTOW aircraft accumulates higher wing loads per flight hour than a 15,000 lb aircraft. The corrected intervals for the heavier aircraft are shorter — meaning inspections and component replacements are required sooner.
My aircraft had a Special Missions wing evaluation by Textron. Am I exempt?
Yes. Aircraft that received a wing evaluation from Textron Aviation Special Missions and were issued a serial-number-specific Aircraft Limitations Manual and SIRM supplement are excluded from this AD.
How urgent is this for Group 3 aircraft (above 7,401 hours TTIS)?
Very. Group 3 aircraft must comply within 25 hours TIS or 30 days after August 10, 2026 — whichever comes first. That is the tightest compliance window in the AD. Confirm your status immediately.
Related Reading:
- Data-Driven Safety Monitoring in General Aviation Faces a Critical Bottleneck
- FAA AD 2026-14-07: Bell 407 Pilot Cyclic Stick Tube Cracking — Repetitive Inspections Required, Loss of Control Risk
aviationregwatch.com publishes regulatory intelligence for aviation compliance professionals. This article is an informational summary, not legal or airworthiness advice. Consult your aircraft manufacturer, CAMO, or legal counsel for compliance decisions.