Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Boeing Model 737-600, -700, and -800 series airplanes, that currently requires repetitive inspections to detect discrepancies of the quick-disconnect coupling on the fuel hose located at the fan case firewall; corrective action, if necessary; and installation of a clamp shell on the coupling to prevent separation of the coupling halves. This action would limit the applicability of the existing requirements, clarify certain existing requirements, and require removal of the clamp shell installed previously and replacement of the existing quick-disconnect fuel supply hose, coupling, and strut fitting with new, fixed-B-nut-type parts. Such replacement would end the requirement for repetitive inspections. This action is necessary to prevent major fuel leakage due to excessive wear of the quick-disconnect coupling on the fuel hose, fire in the engine nacelle, and consequent lossof thrust from the affected engine, which could result in reduced controllability of the airplane. This action is intended to address the identified unsafe condition.