A new US Federal Aviation Administration airworthiness directive affecting certain Textron Aviation King Air B300 and B300C aircraft will take effect on 10 August 2026.
FAA Airworthiness Directive 2026-15-05 was issued following a revision by Textron Aviation to the airworthiness limitations applicable to certain heavyweight aircraft. The FAA said the existing Airworthiness Limitations Manual contained incorrect wing inspection intervals for aircraft certified to or operating at a maximum take-off weight of 16,500 lb.
Textron subsequently revised the B300 and B300C structural inspection and repair information to separate the wing inspection criteria and intervals for aircraft operating at a 15,000 lb maximum take-off weight from those certified to or operating at 16,500 lb.
According to the FAA, the revised criteria are based on aircraft operating hours and are intended to detect cracking in the wing or wing-supporting structure. The authority said an undetected condition could result in reduced structural integrity.
The FAA issued the AD as a final rule with a request for comments rather than following the usual prior notice and comment process. The authority said current data indicated that a number of aircraft had already exceeded the revised inspection intervals, resulting in the shorter implementation period.
The AD was published in the Federal Register on 24 July and becomes effective on 10 August 2026. Comments will be accepted until 8 September 2026. The FAA estimates that 113 US-registered aircraft are affected.
Applicability
The directive does not apply to all King Air 350-series aircraft.
It applies to Textron Aviation Model B300 and B300C aircraft identified in Textron Mandatory Service Letter MTL-57-04 Revision 1, dated 27 March 2025, including specified aircraft fitted with the following modifications:
- B300 heavyweight aircraft with Kit 130-4402
- B300 heavyweight and B300C non-extended-range aircraft with Kit 130-4030
- B300 increased-gross-weight aircraft with extended-range fuel tanks and Kit 130-4014
Each modification carries its own applicable serial-number range.
The AD excludes aircraft that have undergone a wing evaluation by Textron Aviation Special Missions and have subsequently been issued serial-number-specific aircraft limitations and Structural Inspection and Repair Manual supplements.
Compliance Periods
For applicable aircraft certified to or operating at 16,500 lb maximum take-off weight, the required compliance period is determined by total time-in-service.
| Total time-in-service | Compliance period |
| 3,800 hours or less | Before accumulating 3,800 hours TTIS, or within 25 hours TIS or 30 days after 10 August, whichever occurs later |
| 3,801 to 7,400 hours | Within 200 hours TIS or six months after 10 August, whichever occurs first |
| More than 7,401 hours | Within 25 hours TIS or 30 days after 10 August, whichever occurs first |
The AD requires the Limitations Section of the existing aircraft maintenance manual or instructions for continued airworthiness, together with the existing approved maintenance or inspection programme, to be revised by incorporating the information specified by the directive.
Among the revised scheduled component limits listed by the FAA are a 2,500-hour replacement interval for certain wing-to-fuselage attach angles and a 6,500-hour replacement interval for certain outboard wing structures, depending on aircraft serial number and configuration. Later aircraft and aircraft incorporating specified modifications are subject to different requirements.
Textron Mandatory Service Letter MTL-57-04 Revision 1, dated 27 March 2025, is incorporated by reference in the AD. The FAA also identifies the Super King Air B300/B300C Airworthiness Limitations Manual 130-590031-211G, Revision G0, dated 29 April 2026, as additional guidance for accomplishing the required actions.
