AN I-BEAM ON A FLIGHT FEEDER THAT SUPPORTED ROLLERS WAS TWISTED. EE WAS STRAIGHTENING THE I-BEAM BY APPLYING HEAT, USING A COMEALONG & A HYD. JACK. HE WAS REMOVING THE JACK AFTER THE FIRST BEAM WAS STRAIGHTENED WHILE THERE WAS PRESSURE STILL ON THE JACK. THE JACK POPPED OUT & HIT THE EE'S FINGER AGAINST ANOTHER ROLLER.