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Airworthiness Directive 2001-03-51

recurring
Official AD 2001-03-51 · FR doc 01-5165 · 2001-03-06 · airframe

Airworthiness Directives; Sikorsky Aircraft Corporation Model S-76B and S-76C Helicopters

What this AD requires

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 2001-03-51, which was sent previously to all known U.S. owners and operators of Sikorsky Aircraft Corporation (Sikorsky) Model S-76B and S-76C helicopters by individual letters. This AD requires, for certain main rotor shafts, initial and recurring fluorescent penetrant inspections. Replacing each affected main rotor shaft (shaft) on or before reaching 1,000 hours time-in- service (TIS) is also required. This amendment is prompted by four reports of shaft cracks. The actions specified by this AD are intended to prevent failure of the shaft and subsequent loss of control of the helicopter.

Repetitive inspection. Re-inspect every 20 hours. The next-due date/hours depend on this aircraft’s time in service — a records report computes it from the logbooks.

Which aircraft AD 2001-03-51 applies to

MakesSikorsky

Cross-reference boilerplate only; model list precedes excerpt and was not captured. Requires, before further flight and thereafter at intervals not exceeding 20 hours TIS or 80 landings, a fluorescent penetrant inspection of the shaft in the area above the upper shaft output seal and below the lower hub attachment flange, per Sikorsky Alert Service Bulletin No. 76-66-32A, Revision A, dated January 17, 2001; cracked shafts must be replaced before further flight, and all affected shafts must be replaced on or before 1,000 hours TIS (new retirement life).

Whether AD 2001-03-51 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:

Method of compliance — The specific action taken (inspected, replaced, modified) and to what revision.
Date — When the work was done.
Aircraft time — Total time in service / tach at compliance — how recurring next-due is computed.
Signature & certificate — The A&P/IA who returned it to service, with certificate number.
Is AD 2001-03-51 complied with on your aircraft?

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.