AD 76-05-11
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Enstrom Helicopter Corporation, The | 280 | Airworthiness Directives; Enstrom Model F-28A and 280 Helicopters |
| aircraft | Enstrom Helicopter Corporation, The | F-28A | Airworthiness Directives; Enstrom Model F-28A and 280 Helicopters |
Unsafe Condition
Fatigue cracks in tail cone attach bolts, particularly in the threaded area and the radius under the base of the bolt head, could result in tail cone detachment.
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Required Actions
Within 10 hours time in service after the effective date, inspect bolts via dye penetrant or equivalent method. Replace defective bolts before further flight. Within 110 hours, replace AN bolts with specified NAS bolts (NAS146DH-24 for upper, NAS146DH-22 for lower), install MS20002C6 washers, torque to 240 in-lbs, and safety wire. Repeat inspections every 50 hours unless stronger bolts are installed.
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Compliance Time
Within the next ten (10) hours time in service after the effective date of this AD
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Affected Aircraft
Enstrom Model F-28A (S/N 03 thru 347) and 280 (S/N 1001 thru 1030) helicopters certified in all categories.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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