Is AD 99-17-01 a recurring Airworthiness Directive?

No — AD 99-17-01 is a one-time directive. Verify it was complied with in the aircraft's records.

Which aircraft does AD 99-17-01 apply to?

AD 99-17-01 applies to Pilatus Aircraft Ltd. — models PC-12. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 99-17-01

one-time

Official AD 99-17-01 · FR doc 99-20568 · 1999-08-13 · airframe

Airworthiness Directives; Pilatus Aircraft Ltd. Models PC-12 and PC-12/45 Airplanes

What this AD requires

This amendment adopts a new airworthiness directive (AD) that applies to certain Pilatus Aircraft Ltd. (Pilatus) Models PC-12 and PC- 12/45 airplanes. This AD requires replacing all flap drive shafts with flap drive shafts of improved design, installing additional gaskets on the power drive unit, and modifying the attachment and supporting hardware. This AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Switzerland. The actions specified by this AD are intended to prevent the flap drive shafts from corroding to the point where the flexible shafts in the flap drive system rupture, which could result in the inability to utilize the flap system with reduced airplane control.

Which aircraft AD 99-17-01 applies to

MakesPilatus Aircraft Ltd.

ModelsPC-12

Part-conditional — 945.02.02.201, 945.02.02.202.

Applies to Pilatus PC-12 airplanes. Prevents flap drive shafts from corroding to the point that the flexible shafts in the flap drive system rupture, which could result in inability to use the flap system with reduced airplane control. Requires, within 4 calendar months, replacing all flap drive shafts with improved-design shafts (P/N 945.02.02.201 inboard, P/N 945.02.02.202 outboard), installing additional gaskets on the power drive unit, and modifying the attachment/supporting hardware per Pilatus Service Bulletin No. 27-003, dated March 8, 1999. No person may install a flap drive shaft assembly of a superseded part number as of the effective date.

Whether AD 99-17-01 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 99-17-01 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.