Is AD 2018-21-11 a recurring Airworthiness Directive?

Yes — AD 2018-21-11 requires a repetitive inspection. Next-due depends on the aircraft's time in service.

Which aircraft does AD 2018-21-11 apply to?

AD 2018-21-11 applies to Pratt & Whitney Division — models PW4074D, PW4077D, PW4084D, PW4090, PW4090-3, PW4000. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 2018-21-11

recurring

Official AD 2018-21-11 · FR doc 2018-23712 · 2018-10-31 · turbine engine

Airworthiness Directives; Pratt & Whitney Division (PW) Turbofan Engines

What this AD requires

We are adopting a new airworthiness directive (AD) for all Pratt & Whitney Division (PW) PW4074D, PW4077D, PW4084D, PW4090, and PW4090-3 turbofan engines with a low-pressure compressor (LPC) fan hub, part number (P/N) 51B821 or P/N 52B521, installed. This AD was prompted by updated low-cycle fatigue analysis techniques that indicate certain LPC fan hubs could crack before their published life limit. This AD requires repetitive eddy current inspections (ECIs) and fluorescent penetrant inspections (FPIs) for cracks in certain LPC fan hubs and removal of LPC fan hubs from service that fail inspection. We are issuing this AD to address the 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 2018-21-11 applies to

MakesPratt & Whitney Division

ModelsPW4074D, PW4077D, PW4084D, PW4090, PW4090-3, PW4000

Part-conditional — 51B821, 52B521.

Applies only to engines with low-pressure compressor (LPC) fan hub P/N 51B821 or P/N 52B521 installed.

Whether AD 2018-21-11 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 2018-21-11 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.