AD 84-19-51 R1
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky Aircraft Corporation | S-76A | Airworthiness Directives; SIKORSKY AIRCRAFT Model S-76A Helicopters |
Unsafe Condition
Damaged, bent, or fractured center firewall support stiffeners or doublers could cut into the tail rotor driveshaft and cause loss of directional control of the helicopter.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Inspect forward center firewall sections for missing fasteners and proper fit per Sikorsky Alert Service Bulletin 76-53-25. Remove and replace cracked or non-conforming doubler Part Number 76070-20057-101. Ensure rivets are installed correctly. Remove core section from specified horizontal seal parts. Inspect stiffeners and doublers for fractures, distortions, or damage. Check clearance between tail rotor driveshaft and firewall; contact Boston Aircraft Certification Office if inadequate. Helicopters not modified per Customer Service Notice 76-111 must perform specific inspections. Alternate compliance may be approved by the Boston office.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
prior to further flight
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Sikorsky Aircraft Corporation Model S-76A helicopters with Serial Numbers 76006, 76007, 760001 through 760339
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
This site is not affiliated with or endorsed by the FAA. Always verify with official sources.