Is AD 99-11-04 a recurring Airworthiness Directive?

No — AD 99-11-04 is a one-time directive. Verify it was complied with in the aircraft's records.

Which aircraft does AD 99-11-04 apply to?

AD 99-11-04 applies to Sikorsky Aircraft Corporation — models S-76A, S-76. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 99-11-04

one-time

Official AD 99-11-04 · FR doc 99-15901 · 1999-06-24 · appliance

Airworthiness Directives; Sikorsky Aircraft Model S-76A Helicopters

What this AD requires

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 99-11-04 which was sent previously to all known U.S. owners and operators of Sikorsky Aircraft Model S-76A helicopters by individual letters. This AD requires, before further flight, either revising the flight manual to show reduced single-engine rotorcraft performance or determining if an AC generator interlock system is installed. If an interlock system is installed, the flight manual revision is not required. This amendment is prompted by the discovery that Sikorsky Aircraft Model S-76A helicopters with Turbomeca Arriel 1S1 engines may fail to achieve the specified single- engine rotorcraft performance if an AC generator interlock system is not installed. The actions specified by this AD are intended to prevent the inability of the rotorcraft to achieve certain published one- engine-inoperative performance.

Which aircraft AD 99-11-04 applies to

MakesSikorsky Aircraft Corporation

ModelsS-76A, S-76

Serial-conditional — narrows to serials 760001–760237, 760238–?.

Part-conditional — 33776-84790-012, 33776-84790-011.

For S-76A helicopters without an AC generator interlock system installed: insert Sikorsky RFM Supplement (RFMS) No. 29B, Temporary Revision 1, dated April 9, 1999, reducing Category A max takeoff/landing gross weight and single-engine forward climb performance limits, OR verify presence of AC generator interlock relays (labeled K43/K44, or K46/K47/K48) at the No. 2 Relay Panel. For S/N 760001-760237, interlock relays wire through splice groups to K31/K32/K11/K13; for S/N 760238 and higher, wire to K11/K13. The RFM Supplement may be removed upon installing AC generator interlock kit P/N 33776-84790-012 (S/N 760001-760237) or P/N 33776-84790-011 (S/N 760238 and higher). Ref: Sikorsky Alert Service Bulletin 76-77-4A, Revision A, dated May 5, 1999.

Whether AD 99-11-04 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 99-11-04 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.