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Airworthiness Directive 98-21-22

recurring
Official AD 98-21-22 · FR doc 98-27194 · 1998-10-16 · turbine engine

Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan Engines

What this AD requires

This amendment adopts a new airworthiness directive (AD), applicable to Pratt & Whitney JT9D series turbofan engines, that requires initial and repetitive eddy current inspections (ECI) of 14th and 15th stage high pressure compressor (HPC) disks for cracks, and removal of cracked disks and replacement with serviceable parts. This amendment is prompted by reports of disk bore cracks found during shop inspections on both the 14th and 15th stage HPC disks. The actions specified by this AD are intended to prevent 14th and 15th stage HPC disk rupture, which could result in an uncontained engine failure and damage to the aircraft.

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 98-21-22 applies to

MakesPratt & Whitney
ModelsJT9D-59A, JT9D-70A, JT9D-7Q, JT9D-7Q3, JT9D-7R4, JT9D
Part-conditional — 5000814-01, 790014, 789914, 790114, 5000815-01, 5000815-021, 704315, 704315-001.

Applies to engines with specified 14th- and 15th-stage high-pressure compressor (HPC) disks installed (listed part numbers).

Whether AD 98-21-22 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 98-21-22 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.