scope:

Description of Driving Event:

The SSME vertical installer is used to position the engine for installation and removal. Failure of this equipment to maintain positive control could lead to unexpected movement. During visual inspection of the air piston and bore of the vertical installer, it was discovered that the air piston had a scored landring. This condition occurs when the piston sticks in the cylinder (due to lack of lubrication and/ or foreign material in the cylinder). Pressure then builds up until the piston breaks free. When the piston breaks free it can travel to the stops with enough momentum to cause sudden uncontrolled movement of the engine.