Is AD 97-20-16 a recurring Airworthiness Directive?

Yes — AD 97-20-16 requires a repetitive inspection every 100 hours. Next-due depends on the aircraft's time in service.

Which aircraft does AD 97-20-16 apply to?

AD 97-20-16 applies to Eurocopter — models BK117. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 97-20-16

recurring

Official AD 97-20-16 · FR doc 97-26792 · 1997-10-09 · airframe

Airworthiness Directives; Eurocopter Deutschland GmbH (ECD) (Eurocopter) Model MBB-BK117 A-1, A-3, A-4, B-1, B-2, and C-1 Helicopters

What this AD requires

This amendment supersedes an existing airworthiness directive (AD), applicable to Eurocopter Model MBB-BK117 A-1, A-3, A-4, B-1, B-2, and C-1 helicopters, that currently requires initial and repetitive inspections of both surfaces of the tail boom vertical fin (vertical fin) spar, the skin, and the left-hand and right-hand frame sheets for cracks or loose rivets. This amendment requires the same initial and repetitive inspections of the vertical fin spar that are required by the existing AD, and also requires repairing certain cracks, if found, and repairing and reporting loose rivets and certain other cracks, if found. This amendment is prompted by an accident which occurred on April 15, 1997, resulting in one fatality. A subsequent investigation revealed that the vertical fin had failed as a result of a fatigue crack that initiated on the left side of the vertical fin spar cap. The actions specified by this AD are intended to prevent failure of the vertical fin and subsequent loss of control of the helicopter.

Repetitive inspection. Re-inspect every 100 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 97-20-16 applies to

MakesEurocopter

ModelsBK117

Part-conditional — 105-304061.03, 1120-30406.03, 117-30423-03, 105-304011.18, 1120-30402.08.

Tail boom vertical fin spar crack/loose-rivet inspection and repair per Eurocopter Alert Service Bulletin MBB-BK117-30-106 Rev 3 (May 5, 1997).

Whether AD 97-20-16 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 97-20-16 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.