|astronautix.com||Apollo LEM ascent engine exploded during firings|
A LEM ascent engine exploded during altitude firings at Arnold Engineering Development Center (AEDC). In subsequent investigations, Bell Aerosystems researchers concluded that the failure probably resulted from raw propellants being accidentally forced into the engine at the end of the second run, thus damaging the injector.
The explosion, which occurred at the start of the third run, in turn followed an uncontrolled flow of propellants into the engine. As a result of this accident, Bell made several changes in hardware fabrication. Also, the company planned additional firings, under conditions similar to those at AEDC when the explosion occurred, to try to determine exactly the cause. References: 16 .