Regulacje i polityka gospodarcza · 20/11/2000

Airworthiness Directives; Boeing Model 747 Series Airplanes

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to all Boeing Model 747 series airplanes, that currently requires revising the Airplane Flight Manual to include procedures to prevent dry operation of the center wing fuel tank override/jettison pumps and, for certain airplanes, to prohibit operation of the horizontal stabilizer tank transfer pumps in-flight. That AD was prompted by a report indicating that several override/ jettison fuel pumps from the center wing tanks and main tanks had been removed because circuit breakers for the override/jettison fuel pumps were tripped, or low pump output pressure was indicated. For certain airplanes, this action would require installation of improved fuel pumps, which would terminate the requirements of the existing AD. This proposal is prompted by new information received from the fuel pump manufacturer. The actions specified by the proposed AD are intended to prevent contact between the rotating paddle wheel and the stationary end plates within the center wing tank override/jettison fuel pumps or horizontal stabilizer tank transfer pumps, which could cause sparks and/or a hot surface condition