AD 2010-10-02
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky | Aircraft Corporation Model S-76A | Airworthiness Directives; Sikorsky Aircraft Corporation Model S-76A, B, and C Helicopters |
| aircraft | Textron | Various | Airworthiness Directives; Sikorsky Aircraft Corporation Model S-76A, B, and C Helicopters |
Unsafe Condition
High rate of leakage in Woodward HRT main rotor servo actuator due to piston head seal leakage and plasma spray flaking, which could result in degraded servo actuator performance and loss of control.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Inspect each installed Woodward HRT main rotor servo actuator for a high rate of leakage exceeding 700 cc per minute. Replace affected servo actuator piston with a newly designed piston (P/N 41012001 or 41012001-001). Replace affected servo actuator if necessary. Re-identify -109 and -110 servo actuators as -111 servo actuators after installation of new pistons.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within 1,500 hours time-since-new or time-since-overhaul, or upon discovering fluid leakage exceeding 700 cc per minute.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Sikorsky Aircraft Corporation Model S-76A, B, and C helicopters with Woodward HRT main rotor servo actuators, specifically those with overhauled pistons (P/N 41004321 or RW41004321).
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 6, 2026
Rights: U.S. Government Public Domain
This site is not affiliated with or endorsed by the FAA. Always verify with official sources.