Is AD 59-20-01 a recurring Airworthiness Directive?

No — AD 59-20-01 is a one-time directive. Verify it was complied with in the aircraft's records.

Which aircraft does AD 59-20-01 apply to?

AD 59-20-01 applies to Vertol — models 44. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 59-20-01

one-time

AD 59-20-01 · 1959-01-01 · airframe

Airworthiness Directives; VERTOL Model 44 Series Helicopters

Which aircraft AD 59-20-01 applies to

MakesVertol

Models44

Part-conditional — 42R1009-1.

Applies to all Model 44 Series Helicopters. Rotor blade assembly P/N 42R1009-1 in all-metal forward rotor blades to be inspected within the next twenty hours of flight in accordance with Vertol Engineering Order No. 7A (Drawing No. 42R1011).

Whether AD 59-20-01 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 59-20-01 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 →

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.