Abstract: EMPLOYEES #1 AND #2 WERE REPLACING A LEAKING HYDRAULIC CYLINDER ON A HYDRAULIC ELEVATOR. EMPLOYEE #1, THE MECHANIC, WAS IN THE ELEVATOR PIT. HE PLACED AN EXTENSION (SPACER) BETWEEN THE PLATEN OF THE CAB AND THE PISTON, SO THAT WHEN THE CAB WAS RAISED TO THE TOP FLOOR OF THE 7 STORY BUILDIBG, IT COULD BE SECURED THERE. THE EXTENSION WAS SECURED ON ONE SIDE (APPARENTLY TO THE CAB). THE HELPER, LOCATED ON TOP OF THE CAB, THEN RAN THE ELEVATOR AS FAR AS THE SIXTH FLOOR, WHERE IT BEGAN VIBRATING. THE VIBRATION APPARENTLY DISLODGED THE EXTENSION AND SOMEHOW CAUSED THE HYDRAULIC PISTON TO PIERCE THE FLOOR, AND THEN THE ROOF, OF THE ELEVATOR CAR. THE CAR PLUNGED DOWN THE SHAFT TO THE PIT, CRUSHING EMPLOYEE #1 AND SEVERELY INJURING THE BACK OF THE HELPER (EMPLOYEE #2), WHO RODE THE CAR DOWN.