Is AD 98-23-08 a recurring Airworthiness Directive?

No — AD 98-23-08 is a one-time directive. Verify it was complied with in the aircraft's records.

Which aircraft does AD 98-23-08 apply to?

AD 98-23-08 applies to Pratt & Whitney — models PW4152, PW4056, PW4156, PW4256, PW4052, PW4158, PW4060, PW4160. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 98-23-08

one-time

Official AD 98-23-08 · FR doc 98-30320 · 1998-11-13 · turbine engine

Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan Engines

What this AD requires

This amendment adopts a new airworthiness directive (AD), applicable to certain Pratt & Whitney (PW) PW4000 series turbofan engines not incorporating modifications described in certain PW service bulletins listed in the applicability section, that requires high pressure compressor (HPC) blade tip grinding of the rotor assembly, installation of aluminum oxide coated HPC blade tips in stages 9 through 12, modification of HPC 8th through 14th stage stators, incorporation of 1st stage high pressure turbine (HPT) vanes with increased airflow area which also requires additional HPT hardware modifications, and incorporation of HPC 13th-15th stage zirconium oxide blade tips. This amendment is prompted by reports of HPC surge caused by excessive HPC rear stage rotor-to-case clearance. The actions specified by this AD are intended to prevent HPC surge, which can result in engine power loss at a critical phase of flight such as takeoff or climb.

Which aircraft AD 98-23-08 applies to

MakesPratt & Whitney

ModelsPW4152, PW4056, PW4156, PW4256, PW4052, PW4158, PW4060, PW4160, PW4460, PW4050, PW4060A, PW4156A, PW4062, PW4462, PW4060C, PW4650, PW4000

Applies to engines not incorporating at least one of the modifications described in PW service bulletins 72-484, 72-486, 72-575, 72-514, 72-490, 72-504, and 72-572; excludes engines with a '-3' identifier next to the engine model number on the engine data plate.

Whether AD 98-23-08 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 98-23-08 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.