AD 83-04-04
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Enstrom Helicopter Corporation, The | 280 | Airworthiness Directives; ENSTROM HELICOPTER CORPORATION Models F-28A and 280 Helicopters |
| aircraft | Enstrom Helicopter Corporation, The | F-28A | Airworthiness Directives; ENSTROM HELICOPTER CORPORATION Models F-28A and 280 Helicopters |
Unsafe Condition
The possible loss of power to the main rotor due to insufficient thickness of the ring gear carrier lower web in main rotor gearboxes (P/N 28-13101) with specified serial numbers.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Drain oil and remove oil filter cap assembly. Inspect ring gear carrier lower web thickness using inspection tool T-0125 at three hole locations. Replace unairworthy ring gear carriers (P/N 28-13106, Rev. F or later) if the tool indicates insufficient thickness. Reinstall oil and cap per manual.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within the next 25 hours' time in service from the effective date of this AD
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Affected Aircraft
Enstrom Helicopter Corporation Models F-28A and 280 with main rotor gearboxes (P/N 28-13101) having the listed serial numbers: [extensive list of serial numbers provided in the source]
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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