Is AD 2021-04-12 a recurring Airworthiness Directive?

No — AD 2021-04-12 is a one-time directive. Verify it was complied with in the aircraft's records.

Which aircraft does AD 2021-04-12 apply to?

AD 2021-04-12 applies to Robinson Helicopter Company. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 2021-04-12

one-time

Official AD 2021-04-12 · FR doc 2021-03656 · 2021-03-08 · airframe

Airworthiness Directives; Robinson Helicopter Company Helicopters

What this AD requires

The FAA is adopting a new airworthiness directive (AD) for Robinson Helicopter Company (Robinson) Model R66 helicopters. This AD was prompted by reports of tail rotor (T/R) drive shaft forward hanger bearing failures. This AD requires installing a certain part numbered kit and removing parts from service or replacing a certain part- numbered T/R drive shaft assembly. This AD also prohibits the installation of certain parts. The FAA is issuing this AD to address the unsafe condition on these products.

Which aircraft AD 2021-04-12 applies to

MakesRobinson Helicopter Company

Part-conditional — D224-4, D224-5, KI-235.

Extracted applicability text is an excerpt from the AD's comment-response/background discussion, not the formal applicability paragraph, so the specific helicopter model and serial-number range could not be reliably determined. Text concerns a Robinson tail rotor (T/R) drive shaft assembly: forward hanger bearing kit P/N KI-235 upgrades the T/R drive shaft assembly to yoke P/N D224-5; T/R drive shaft assembly P/N D224-4 (installed on certain serial-numbered helicopters during production) is explicitly stated as NOT affected by this AD. Related service info referenced: Robinson SB-14, SB-20, SB-20A, SB-20B.

Whether AD 2021-04-12 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 2021-04-12 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.