Airworthiness Directives; Boeing Model 707 Airplanes and Model 720 and 720B Series Airplanes

The FAA is adopting a new airworthiness directive (AD) for all Boeing Model 707 airplanes and Model 720 and 720B series airplanes. This AD requires performing an operational test of the engine fuel suction feed of the fuel system, and other related testing and corrective actions if necessary. This AD results 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. We are issuing this AD 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.