Airworthiness Directives; Boeing Model 747 Series Airplanes

This amendment supersedes an existing airworthiness directive (AD), applicable to all Boeing Model 747 series airplanes, that currently requires, for certain airplanes, revising the Airplane Flight Manual, and, for all airplanes, performing repetitive inspections for wear or damage of the inlet check valves and inlet adapters of the override/jettison pumps, and corrective actions, if necessary. This amendment applies to fewer airplanes than the existing AD and requires rework of certain components, which ends the repetitive inspection requirement. These actions are necessary to ensure that the flight crew is advised of the hazards of dry operation of the override/jettison pumps of the center wing fuel tank, and to prevent wear or damage to the inlet check valves and inlet adapters of the override/jettison pumps, which could result in a fire or explosion in the fuel tank during dry (no fuel) operation. This action is intended to address the identified unsafe condition.