Is AD 2021-23-06 a recurring Airworthiness Directive?

Yes — AD 2021-23-06 requires a repetitive inspection every 3000 hours. Next-due depends on the aircraft's time in service.

Airworthiness Directive 2021-23-06

Q: Which aircraft does AD 2021-23-06 apply to?

AD 2021-23-06 applies to Columbia Helicopters, Inc., Billings Flying Service, Inc., Tandem Rotor, Llc, Unical Aviation, Inc. — models 234, CH-47D, CH-47. Serial/part conditions may narrow it to specific aircraft.

recurring

Official AD 2021-23-06 · FR doc 2021-27539 · 2021-12-20 · airframe

Airworthiness Directives; Various Model 234 and Model CH-47D Helicopters

What this AD requires

The FAA is adopting a new airworthiness directive (AD) for various Model 234 and Model CH-47D helicopters. This AD was prompted by two reports of mechanical failures of the longitudinal cyclic trim actuator (LCTA). This AD requires determining the maintenance history, and hours time-in-service (TIS) and number of lift cycles for each LCTA since last overhaul, and then requires initial and repetitive overhauls of each LCTA based on that maintenance and service history. This AD also prohibits installing an LCTA unless it meets certain requirements. Finally, this AD requires reporting certain information to the FAA. The FAA is issuing this AD to address the unsafe condition on these products.

Repetitive inspection. Re-inspect every 3000 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 2021-23-06 applies to

MakesColumbia Helicopters, Inc.Billings Flying Service, Inc.Tandem Rotor, LlcUnical Aviation, Inc.

Models234, CH-47D, CH-47

Applies regardless of type certificate holder; the listed holders (Columbia Helicopters, Billings Flying Service, Tandem Rotor LLC, Unical Aviation) are non-exhaustive.

Whether AD 2021-23-06 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 2021-23-06 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.