Airworthiness Directives; Boeing Model 727-100 and -200 Series Airplanes With a Main Deck Cargo Door Installed in Accordance With Supplemental Type Certificate (STC) SA1797SO

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Boeing Model 727-100 and -200 series airplanes. This action requires an inspection to detect discrepancies of internal wires and electrical components of the control box of the main deck cargo door; modification of the wiring and components of the control box of the main deck cargo door; and a revision of the Airplane Flight Manual to impose an operational limitation of the motor pump power relay and pump motor. This amendment is prompted by results of an engineering review of the wiring diagram of the main deck cargo door installations, which revealed potential failures of the control box and hydraulic pump assembly installed in accordance with the STC. The actions specified in this AD are intended to prevent such failures, which could result in an inadvertent opening of the main deck cargo door during flight, with resultant major structural damage and possible reduced controllability of the airplane.