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

Yes — AD 99-11-11 requires a repetitive inspection every 12 hours. Next-due depends on the aircraft's time in service.

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

AD 99-11-11 applies to Eurocopter — models SA-365N, SA-365N1, SA-365N2, SA-365N3, SA-366G1, SA-365, SA-366. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 99-11-11

recurring

Official AD 99-11-11 · FR doc 99-13320 · 1999-05-26 · airframe

Airworthiness Directives; Eurocopter France Model SA-365N, N1, N2, N3, and SA-366G1 Helicopters

What this AD requires

This amendment supersedes an existing airworthiness directive (AD), applicable to Eurocopter France Model SA-365N, N1 and SA-366G1 helicopters, that currently requires repetitive inspections of the main gearbox (MGB) magnetic chip plug and oil filter if certain part number/ modification level MGB's are installed. This new action expands the helicopter model and MGB applicability to include the SA-365N2 and N3 helicopters and all variants of the MGB. It also requires installing a MGB planetary gear shaft (gear shaft) vibration level monitoring unit (VLMU); inserting procedures into the Rotorcraft Flight Manual (RFM) for a preflight vibration check using the VLMU and inserting a related emergency procedure and limitation for an inoperative VLMU into the RFM. This action is prompted by two occurrences of gear shaft cracks. The actions specified by this AD are intended to detect cracks in the MGB planetary gear shaft, which could lead to failure of the MGB and subsequent loss of control of the helicopter.

Repetitive inspection. Re-inspect every 12 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 99-11-11 applies to

MakesEurocopter

ModelsSA-365N, SA-365N1, SA-365N2, SA-365N3, SA-366G1, SA-365, SA-366

Main gearbox (MGB) planetary gear shaft crack-detection AD; requires installing a shaft vibration level monitoring unit (VLMU) per Eurocopter AS 365 SB No. 31.00.03 (applicable to Model SA-365N, N1, N2, N3) or Eurocopter SA 366 SB No. 31.01 (applicable to Model SA-366G1), both dated June 23, 1998.

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