Is AD 2015-21-04 a recurring Airworthiness Directive?

No — AD 2015-21-04 is a one-time directive. Verify it was complied with in the aircraft's records.

Airworthiness Directive 2015-21-04

Q: Which aircraft does AD 2015-21-04 apply to?

AD 2015-21-04 applies to Pratt & Whitney — models PW4164, PW4168, PW4168A, PW4164-1D, PW4168-1D, PW4168A-1D, PW4170, PW4000. Serial/part conditions may narrow it to specific aircraft.

one-time

Official AD 2015-21-04 · FR doc 2015-26346 · 2015-10-23 · turbine engine

Airworthiness Directives; Pratt & Whitney Turbofan Engines

What this AD requires

We are adopting a new airworthiness directive (AD) for certain Pratt & Whitney (PW) PW4164, PW4168, PW4168A, PW4164-1D, PW4168-1D, PW4168A-1D, and PW4170 turbofan engines. This AD was prompted by crack finds in the 6th stage low-pressure turbine (LPT) disk. This AD requires removal of the affected 6th stage LPT disks. We are issuing this AD to prevent failure of the 6th stage LPT disk, which could lead to an uncontained disk release, damage to the engine, and damage to the airplane.

Which aircraft AD 2015-21-04 applies to

MakesPratt & Whitney

ModelsPW4164, PW4168, PW4168A, PW4164-1D, PW4168-1D, PW4168A-1D, PW4170, PW4000

Part-conditional — 50N886.

Applies only to engines with 6th stage low-pressure turbine (LPT) disk, P/N 50N886, installed.

Whether AD 2015-21-04 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 2015-21-04 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.