Airworthiness Directive 98-23-07
one-timeAirworthiness Directives; Pratt & Whitney JT9D Series Turbofan Engines
What this AD requires
This amendment adopts a new airworthiness directive (AD), applicable to certain Pratt & Whitney (PW) JT9D series turbofan engines, that requires a one-time acid etch inspection of the turbine exhaust case (TEC) wall between and on either side of the ``R'' and ``S'' rails in the engine mount lug area (top quadrant of the case) for the presence of weld material, and if weld material is detected, removal from service and replacement with serviceable parts. This amendment is prompted by reports of weld rework performed in the outer case wall of the TEC, in the mount lug fillet area, during original production to address local under minimum wall thickness conditions which have left the TEC's structural capability compromised. The actions specified by this AD are intended to prevent TEC structural failure under abnormal operating conditions, which could result in reduced main mount load capability, engine separation from the wing and subsequent loss of control of the aircraft.
Which aircraft AD 98-23-07 applies to
Whether AD 98-23-07 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:
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.