Is AD 98-12-07 a recurring Airworthiness Directive?

No — AD 98-12-07 is a one-time directive. Verify it was complied with in the aircraft's records.

Which aircraft does AD 98-12-07 apply to?

AD 98-12-07 applies to Pratt & Whitney — models JT8D-1, JT8D-1A, JT8D-1B, JT8D-7, JT8D-7A, JT8D-7B, JT8D-9, JT8D-9A. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 98-12-07

one-time

Official AD 98-12-07 · FR doc 98-15086 · 1998-06-09 · turbine engine

Airworthiness Directives; Pratt & Whitney JT8D Series Turbofan Engines

What this AD requires

This amendment supersedes an existing airworthiness directive (AD), applicable to Pratt & Whitney JT8D series engines, that currently requires a determination of the utilization rate and coating type of the 7th, 8th, 9th, 10th, 11th, and 12th stage high pressure compressor (HPC) disks, and removal, inspection for corrosion, and recoating of those HPC disks based on utilization rate. This amendment shortens the inspection interval for certain low utilization disks. This amendment is prompted by reports of an additional uncontained 9th stage HPC disk failure due to corrosion pitting. The actions specified by this AD are intended to prevent fracture of the HPC disks, which can result in uncontained release of engine fragments, inflight engine shutdown, and airframe damage.

Which aircraft AD 98-12-07 applies to

MakesPratt & Whitney

ModelsJT8D-1, JT8D-1A, JT8D-1B, JT8D-7, JT8D-7A, JT8D-7B, JT8D-9, JT8D-9A, JT8D-11, JT8D-15, JT8D-15A, JT8D-17, JT8D-17A, JT8D-17R, JT8D-17AR, JT8D

Installed on but not limited to Boeing 737 and 727 series, and McDonnell Douglas DC-9 series aircraft.

Whether AD 98-12-07 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 98-12-07 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.