Summary
We are revising an earlier proposed airworthiness directive (AD) for certain Boeing Model 727 airplanes. The original NPRM would have required performing an operational test of the engine fuel suction feed of the fuel system, and other related testing if necessary. The original NPRM resulted from a report of in-service occurrences of loss of fuel system suction feed capability, followed by total loss of pressure of the fuel feed system. This action revises the original NPRM by reducing the compliance time for low-utilization airplanes and including corrective actions that were inadvertently omitted from certain sections. The corrective actions are inspecting and repairing or replacing any leaking Gamah fittings with new fittings, and inspecting and repairing any major welded tube assemblies that are leaking. We are proposing this supplemental NPRM to detect and correct failure of the engine fuel suction feed capability of the fuel system, which could result in multi-engine flameout, inability to restart the engines, and consequent forced landing of the airplane.