Summary
The FAA is revising an earlier proposed airworthiness directive (AD) for all Boeing Model 767 airplanes. The original NPRM would have required an inspection of each main tank fuel boost pump for the presence of a pump shaft flame arrestor, and if the flame arrestor is missing, replacement of that pump with a pump having a pump shaft flame arrestor. The original NPRM would also have required repetitive measurements of the flame arrestor's position in the pump, and corrective actions if necessary. The original NPRM resulted from reports that certain fuel boost pumps may not have flame arrestors installed in the pump shaft and reports that the pin that holds the flame arrestor in place can break due to metal fatigue. This action revises the original NPRM by proposing the replacement of the pump with a new or modified pump, which would end the repetitive measurements. This action also revises the compliance times for certain airplanes. We are proposing this supplemental NPRM to prevent the possible migration of a flame from a main tank fuel boost pump inlet to the vapor space of that fuel tank, and consequent ignition of fuel vapors, which could result in a fire or explosion.