scope:

Description of Driving Event:

A mishap occurred when technicians did not follow the sequence of events specified in the PR disposition for assembly of the thruster and fixture. The T-shaped mounting fixture was secured with only one C-clamp to an access platform's kick plate that had vinyl tape on both sides. The C-clamp was improperly used to prevent rotation and the vinyl tape acted as a lubricant between the clamped surfaces. These conditions allowed the offset weight of the mounting fixture/thruster assembly to overcome the clamping force and rotate about the single C-clamp and fall.