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Airworthiness Directive 2000-12-21

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Official AD 2000-12-21 · FR doc 00-15545 · 2000-06-23 · airframe

Airworthiness Directives; Boeing Model 747-400 Series Airplanes Equipped with Pratt & Whitney PW4000 Series Engines

What this AD requires

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747-400 series airplanes. The AD requires installation of a modification of the thrust reverser control and indication system and wiring on each engine; and repetitive functional tests of that installation to detect discrepancies, and repair, if necessary. This amendment is prompted by the results of a safety review, which revealed that in-flight deployment of a thrust reverser could result in a significant reduction in airplane controllability. The actions specified by this AD are intended to ensure the integrity of the fail-safe features of the thrust reverser system by preventing possible failure modes, which could result in inadvertent deployment of a thrust reverser during flight, and consequent reduced controllability of the airplane.

Repetitive inspection. Re-inspect every 4000 hours. The next-due date/hours depend on this aircraft’s time in service — a records report computes it from the logbooks.

Which aircraft AD 2000-12-21 applies to

MakesBoeing
Models747-400, 747

Requires installing an additional thrust reverser locking system per Boeing SB 747-78-2155 Rev 2 (terminating action for AD 94-15-05 inspections), plus related SB 747-45-2016 Rev 1 (CMCS), SB 747-31-2245 (IDS software), and SB 747-78-2154 Rev 3 (provisional wiring); repetitive functional tests per Appendix 1 and the Boeing 747-400 Airplane Maintenance Manual.

Whether AD 2000-12-21 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 2000-12-21 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.