Is AD 99-12-01 a recurring Airworthiness Directive?

Yes — AD 99-12-01 requires a repetitive inspection. Next-due depends on the aircraft's time in service.

Which aircraft does AD 99-12-01 apply to?

AD 99-12-01 applies to Eurocopter — models EC135. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 99-12-01

recurring

Official AD 99-12-01 · FR doc 99-16591 · 1999-07-01 · airframe

Airworthiness Directives; Eurocopter Deutschland (Eurocopter) Model EC135 Helicopters

What this AD requires

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 99-12-01, which was sent previously to all known U.S. owners and operators of Eurocopter Model EC135 helicopters by individual letters. This AD requires initial and repetitive visual inspections and one dye-penetrant inspection of the main rotor hub shaft (shaft) for cracks. If a crack is found during any of the inspections, this AD requires replacing the shaft with an airworthy shaft before further flight. This amendment is prompted by the discovery of fatigue cracks on the shaft of a helicopter. The actions specified by this AD are intended to detect fatigue cracks in the shaft that could lead to shaft failure and subsequent loss of control of the helicopter.

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

Which aircraft AD 99-12-01 applies to

MakesEurocopter

ModelsEC135

Part-conditional — L623M100S101.

Applies to helicopters with tail rotor drive shaft P/N L623M100S101. Repetitive visual crack inspection every 15 hr TIS plus a one-time dye-penetrant inspection within 10 hr TIS, per Eurocopter EC135 Alert Service Bulletin EC 135-62A-004, Revision 1, dated May 7, 1999; replace cracked shaft before further flight.

Whether AD 99-12-01 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 99-12-01 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.