Is AD 85-23-51 R1 a recurring Airworthiness Directive?

No — AD 85-23-51 R1 is a one-time directive. Verify it was complied with in the aircraft's records.

Which aircraft does AD 85-23-51 R1 apply to?

AD 85-23-51 R1 applies to Boeing Vertol Company — models 234. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 85-23-51 R1

one-time

AD 85-23-51 R1 · 1985-01-01 · airframe

Airworthiness Directives; telegraphic AD T85-23-51 issued November 20, 1985, which contained part of this amendment. FOOTER: Columbia Helicopters, Inc. 234

Which aircraft AD 85-23-51 R1 applies to

MakesBoeing Vertol Company

Models234

References telegraphic AD T85-23-51, issued November 20, 1985, which contained part of this amendment. Applies to Model 234 series helicopters; effective March 31, 1986.

Whether AD 85-23-51 R1 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 85-23-51 R1 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.

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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.