EE WAS WORKING OUT OF A MANLIFT BASKET. AN AIR POWERED RIVET BUSTER WITH A SHORT, BLUNT BIT WAS USED TO PUSH ON BOLTS. HE HAD THE TRIGGER HANDLE IN HIS RT. HAND & WAS HOLDING THE BODY OF THE BUSTER WITH HIS LEFT HAND AT ABOUT A 45 DEGREE ANGLE UPWARD. HE HAD TAKEN HIS HAND OFF THE TRIGGER BUT IT DID NOT SHUT OFF, HE LOWERED IT TO CHECK & HE HIT HIS RT.ELBOW ON HANDRAIL, BIT CUT.