Is AD 98-21-27 a recurring Airworthiness Directive?

No — AD 98-21-27 is a one-time directive. Verify it was complied with in the aircraft's records.

Which aircraft does AD 98-21-27 apply to?

AD 98-21-27 applies to Pilatus — models PC-12, PC-12/45. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 98-21-27

one-time

Official AD 98-21-27 · FR doc 98-27331 · 1998-10-16 · 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 Pilatus Aircraft Ltd. (Pilatus) Models PC-12 and PC-12/45 airplanes that are equipped with the ``corporate commuter cabin layout.'' This layout is a Pilatus designation only and the affected airplanes are not certificated for commuter operation. This AD requires modifying the passenger seats and seat rail covers. 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 passenger injuries because the passenger seat configuration has been found to not fully meet current head injury criteria regulations.

Which aircraft AD 98-21-27 applies to

MakesPilatus

ModelsPC-12, PC-12/45

Serial-conditional — narrows to serials MSN 101–MSN 230.

Applies only to aircraft equipped with the corporate commuter cabin layout.

Whether AD 98-21-27 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 98-21-27 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.