Is AD 2021-05-21 a recurring Airworthiness Directive?

Yes — AD 2021-05-21 requires a repetitive inspection. Next-due depends on the aircraft's time in service.

Which aircraft does AD 2021-05-21 apply to?

AD 2021-05-21 applies to Leonardo S.P.A. — models AB139, AW139. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 2021-05-21

recurring

Official AD 2021-05-21 · FR doc 2021-06773 · 2021-04-02 · airframe

Airworthiness Directives; Leonardo S.p.a. (Type Certificate Previously Held by Agusta S.p.A.) Helicopters

What this AD requires

The FAA is superseding Airworthiness Directive (AD) 2017-23-08 for Agusta S.p.A. (now Leonardo S.p.a.) Model AB139 and AW139 helicopters. AD 2017-23-08 required repetitively inspecting the main rotor (M/R) rotating scissors, removing certain lower half scissor spherical bearings (bearings) from service, replacing the removed bearings with a new bearing, and installing a special nut. This new AD retains the requirements of AD 2017-23-08 and requires replacing each affected bearing with a certain part-numbered bearing. This AD was prompted by investigation results determining that a quality control issue may have affected the production of the affected bearings. The actions of this AD are intended to address an unsafe condition on these products.

Repetitive inspection. Re-inspect. The next-due date/hours depend on this aircraft’s time in service — a records report computes it from the logbooks.

Which aircraft AD 2021-05-21 applies to

MakesLeonardo S.P.A.

ModelsAB139, AW139

Part-conditional — 3G6230V00654.

Applies only when a main rotor (M/R) rotating scissors lower half scissor spherical bearing P/N 3G6230V00654 is installed. Replaces AD 2017-23-08.

Whether AD 2021-05-21 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 2021-05-21 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.