Airworthiness Directive 2010-23-24
one-timeAirworthiness Directives; Sikorsky Aircraft Corporation (Sikorsky) Model S-70A and S-70C Helicopters
What this AD requires
This amendment adopts a new airworthiness directive (AD) for the Sikorsky Model S-70A and S-70C helicopters. This AD requires an ultrasonic test (UT) inspection of the tail gearbox output bevel gear (gear) for a crack. If you find a crack, replacing the gear with an airworthy gear is required before further flight. This AD is prompted by three gear cracking incidents, one of which resulted in the tail rotor separating from the helicopter. The actions specified by this AD are intended to detect a crack in the gear to prevent a tail rotor separating, loss of tail rotor control, and subsequent loss of control of the helicopter.
Which aircraft AD 2010-23-24 applies to
Applicability depends on the aircraft’s type certificate — check it against the specific tail.
Whether AD 2010-23-24 actually applies to your aircraft (by serial and installed parts) and whether it’s already complied with comes from that aircraft’s records.
How AD compliance is recorded
A valid compliance record (14 CFR 43.9) states:
Tailplate reads a tail number’s logbooks and matches every applicable AD — including this one — to its compliance evidence, with recurring next-due dates computed.
Look up a tail number →Read the full directive (Federal Register)Applicability is derived from the FAA directive corpus and is advisory, not a legal airworthiness determination. Compliance is established only from an aircraft’s actual records.