Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to all Boeing Model 767 series airplanes, that currently requires a revision of the Airplane Flight Manual (AFM) to include procedures that will ensure that the center tank fuel pumps are not operated with less than 1,000 pounds of fuel in the center tank. This proposed AD would require a further revision of the AFM to specify conditions for minimum fuel weight requirements and procedures for ground transfer of fuel for certain airplanes, repetitive inspections to detect discrepancies of the center tank override/jettison fuel pumps, and replacement of any discrepant pump with a new or serviceable pump. This proposal would also require that any override/jettison pump that incorporates a configuration without a diffuser be restored to a configuration that incorporates a diffuser. This proposed AD would also require installation of a new configuration center tank fuel pump, which would terminate the AFM revisions regarding fuel system operating procedures and repetitive inspection requirements. This proposal is prompted by reports of cracks detected in the override/jettison fuel pump inlet diffuser. The actions specified by the proposed AD are intended to prevent ignition of fuel vapors due to the generation of sparks, to prevent a potential ignition source inside the fuel tank caused by metal-to-metal contact during dry fuel pump operation, and to ensure satisfactory fuel pump and fuel system operation.