An employee was called to repair a leaking lift cylinder on a forklift that was outdoors. The employee set the parking brake, tilted the mast to a vertical position and extended the mast to gain access to the secondary lift cylinder. The employee was standing on the dashboard cowling of the forklift between the mast and the overhead roof structure. Thee employee's foot engaged the tilt lever on the forklift, and the mast tilted backward and pinned the employee between the mast and roof structure. The employee suffered a fractured pelvis and ruptured stomach, requiring surgery.