Is AD 2021-05-16 a recurring Airworthiness Directive?

Yes — AD 2021-05-16 requires a repetitive inspection. Next-due depends on the aircraft's time in service.

Airworthiness Directive 2021-05-16

Q: Which aircraft does AD 2021-05-16 apply to?

AD 2021-05-16 applies to Pratt & Whitney Division — models PW4164, PW4164-1D, PW4168, PW4168-1D, PW4168A, PW4168A-1D, PW4170, PW4000. Serial/part conditions may narrow it to specific aircraft.

recurring

Official AD 2021-05-16 · FR doc 2021-06804 · 2021-04-02 · turbine engine

Airworthiness Directives; Pratt & Whitney Division Turbofan Engines

What this AD requires

The FAA is adopting a new airworthiness directive (AD) for certain Pratt & Whitney Division (PW) PW4164, PW4164-1D, PW4168, PW4168-1D, PW4168A, PW4168A-1D, and PW4170 model turbofan engines. This AD was prompted by several reports of low-pressure turbine (LPT) 4th- stage vane cluster assemblies leaning back and notching into the rotating LPT 4th-stage blades, causing some blades to fracture and release. This AD requires initial and repetitive replacements of the LPT 4th-stage air sealing ring segment assemblies with parts eligible for installation. This AD also requires initial and repetitive dimensional inspections of the LPT case for bulging and, depending on the results of the dimensional inspections, repair or replacement of the LPT case. The FAA is 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 2021-05-16 applies to

MakesPratt & Whitney Division

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

Part-conditional — 50N463-01, 50N526-01.

Applies only to engines with low-pressure turbine (LPT) 4th-stage air sealing ring segment assemblies, P/N 50N463-01 or P/N 50N526-01, installed.

Whether AD 2021-05-16 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 2021-05-16 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.