N977FD accident at Chattanooga, TN

The failure of the alternate gear extension system, which prevented the landing gear from being lowered. The cause of the system failure was a broken wire, due to tensile overload, between the alternate gear extend switch and the alternate extension power pack (AEPP), preventing the AEPP from energizing and supplying hydraulic fluid to the door lock release actuators for the nose landing gear and main landing gear. Contributing to the accident was the loss of the left hydraulic system due to a ruptured left main gear door actuator hose from fatigue, which prevented normal landing gear operation.