Airworthiness Directive 2000-21-06
one-timeAirworthiness Directives; Boeing Model 747 Series Airplanes Equipped with Pratt & Whitney (PW) JT9D-7Q and JT9D-7Q3 Turbofan Engines
What this AD requires
This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747 series airplanes, that requires a detailed visual inspection to detect evidence of wear or contact between the precooler support fitting and link assembly; and rework and reidentification of the fitting. This amendment is prompted by a report of rupturing of a diffuser case on a PW JT9D-7Q engine due to cracking in the outer pressure wall in the rear skirt area. The actions specified by this AD are intended to prevent contact between the precooler support link and the precooler support fitting, which could contribute to an uncontained failure of the diffuser case and damage to the airplane.
Which aircraft AD 2000-21-06 applies to
Applies where precooler support fitting P/N 65B90924-1 or 65B90924-600 has not been reworked/reidentified per Boeing Service Letter 747-SL-36-089 (dated August 10, 1998). Detailed visual inspection required for contact wear against link assembly P/N 69B93162-1 or -3; fitting reworked and reidentified as P/N 65B90924-601.
Whether AD 2000-21-06 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.