Abstract: At approximately 7:00 a.m., Employee #1, a construction mechanic, was about to replace an air brake diaphragm on the right front wheel of an FMC hydraulic crane (Serial #45G9-991D). This could have been done without disturbing the spring housing, which would set the brake if air pressure was lost. The employee noticed that the two-bolt clamp that secures the spring cover was loose on one side, and he thought it was unsafe to work on the diaphragm without tightening the clamp. He also decided to tighten both nuts equally. He took a few turns down on the loose side and then backed off the tight side a few turns before going back to tighten the loose side. The cover flew off and struck him in the right side of his forehead. Employee #1 did not lose consciousness but thought he had lost part of his head. He was transported to a nearby hospital, where he received stitches and was released. Apparently, one of the two ears had broken off the cover. (The cover was no longer on the site at the time of the inspection.)