Airworthiness Directive 2000-12-21
recurringAirworthiness Directives; Boeing Model 747-400 Series Airplanes Equipped with Pratt & Whitney PW4000 Series Engines
What this AD requires
This document corrects information in an existing airworthiness directive (AD) that applies to certain Boeing Model 747- 400 series airplanes. That AD currently 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 document publishes Appendix 1, which was referenced in, but inadvertently omitted from, the existing AD. Appendix 1 describes procedures for a functional test to detect discrepancies of the additional locking system on each engine thrust reverser. This correction is necessary to ensure that operators have the procedures necessary to perform the required functional test.
Which aircraft AD 2000-12-21 applies to
Restates/supersedes AD 94-15-05 requirements to install an additional thrust reverser locking system per Boeing SB 747-78-2155 Rev 2, with 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:
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.