Airworthiness Directive · Amendment 39-9321 · The Boeing Company Airplanes
The Boeing Company Airplanes
Superseded. A later AD replaced this one: AD 2003-20-16. Comply with the one in force.
This AD applies to The Boeing Company 747-100 Series, 747-100B Series, 747-100B SUD Series, 747-200B Series, 747-200C Series, 747-200F Series, 747-300 Series, 747SP Series, 747SR Series.
The models as the FAA's AD index lists them. The serial ranges, installed parts and exceptions are in the AD itself: read it at the FAA.
This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747 SP, SR, -100, -200, and -300 series airplanes, that requires repetitive operational tests of the reversible gearbox pneumatic drive unit (PDU) or the reversing air motor PDU to ensure that the unit can restrain the thrust reverser sleeve, and correction of any discrepancy found. This amendment is prompted by the results of an investigation, which revealed that, in the event of thrust reverser deployment during high-speed climb or during cruise, these airplanes could experience control problems. 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 in the thrust reverser control system that can result in inadvertent deployment of a thrust reverser during flight.
