EE WAS GOING TO USE A PNEUMATIC RIVET BUSTER BUTIT WOULD NOT FUNCTION. INVESTIGATING, HE SHUT THE AIR OFF BUT DID NOT DISCONNECT THE HOSE. AFTERHE OPENED THE END CAP HE STUCK HIS FINGER INTO THE CYLINDER & AT THAT MOMENT THE TOOL ACTUATED PINCHING HIS FINGER, REQUIRING 4 SUTURES. HE HADBLED AIR PRESSURE OFF BEFORE OPENING THE TOOL BUT THERE WAS STILL ENOUGH PRESSURE FOR OPERATION.