AD 99-11-04
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky Aircraft Corporation | S-76A | Airworthiness Directives; Sikorsky Aircraft Model S-76A Helicopters |
Unsafe Condition
Sikorsky Model S-76A helicopters with Turbomeca Arriel 1S1 engines may fail to achieve specified single-engine rotorcraft performance if an AC generator interlock system is not installed.
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Required Actions
Before further flight, either revise the Rotorcraft Flight Manual (RFM) to reduce Category 'A' maximum takeoff and landing gross weights by 150 pounds and single-engine forward climb performance by 50 feet per minute, or inspect for the presence of AC generator interlock relays (K43/K44 or K46/K47/K48). If interlock relays are not installed, revise the RFM as specified.
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Compliance Time
Before further flight
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Affected Aircraft
Sikorsky Model S-76A helicopters with Turbomeca Arriel 1S1 engines installed under Supplemental Type Certificate SH568NE (drawing 76070-30601)
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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