Airworthiness Directives; Boeing Model 737-100, -200, -200C, -300, -400, and -500 Series Airplanes

Publication summary

The FAA is superseding an existing airworthiness directive (AD) that applies to all Model 737-100, -200, -300, -400, and -500 series airplanes. The existing AD currently requires repetitive detailed inspections for damage of the electrical wire and sleeve that run through a conduit in the fuel tank to the fuel boost pump, and related investigative and corrective actions; as applicable. This new AD removes certain inspection requirements. This new AD adds repetitive detailed inspections for damage of the electrical wire and sleeve that run to the fuel boost pump through a conduit in the fuel tank, and arcing damage of the conduit and signs of fuel leakage into the conduit; replacement of the sleeve with a new, smaller-diameter sleeve; and related investigative and corrective actions, as applicable. This AD also adds airplanes to the applicability. Accomplishment of the initial new inspection and the sleeve installation terminates the requirements of the existing AD. This new AD results from a report of a fuel tank explosion on a Model 727-200F airplane on the ground, and a report of chafed wires and a damaged power cable sleeve of a fuel boost pump discovered during an inspection on a Model 737-300 airplane. We are issuing this AD to detect and correct chafing of the fuel boost pump electrical wiring and leakage of fuel into the conduit, and to prevent electrical arcing between the wiring and the surrounding conduit, which could result in arc-through of the conduit, and consequent fire or explosion of the fuel tank.