Is AD 2012-21-10 a recurring Airworthiness Directive?

No — AD 2012-21-10 is a one-time directive. Verify it was complied with in the aircraft's records.

Which aircraft does AD 2012-21-10 apply to?

AD 2012-21-10 applies to Boeing — models 777-200LR, 777-300ER, 777. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 2012-21-10

one-time

Official AD 2012-21-10 · FR doc 2012-26074 · 2012-10-30 · airframe

Airworthiness Directives; The Boeing Company Airplanes

What this AD requires

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 777-200LR and -300ER series airplanes. This AD requires reviewing the airplane's maintenance records for each rudder power control unit (PCU) to identify the condition of its related reaction link assembly, and replacing the rudder PCU and its related reaction link assembly if necessary. This AD was prompted by a report of an abnormal airframe vibration in the aft fuselage during flight. We are issuing this AD to prevent excessive freeplay in the rudder control surface, which could cause rudder vibration, and result in structural damage severe enough to prevent continued safe flight and landing.

Which aircraft AD 2012-21-10 applies to

MakesBoeing

Models777-200LR, 777-300ER, 777

Limited to airplanes identified in Boeing Alert Service Bulletin 777-27A0109, dated December 1, 2011.

Whether AD 2012-21-10 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 2012-21-10 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.