Abstract: At approximately 8:30 a.m. on May 22, 1991, Employee #1, a 31-year-old truck driver with over 10 years of experience, was delivering an undetermined amount of liquid sulfonic acid to Union City, CA. He noticed a leak from the packing glands of the Roper pump. Leaks were caused by vibrations from the road while driving. He decided to tighten the nuts on the gland. He slowed the motor to idle and used an 11/16 open wrench to tighten the outboard nut on the packing sleeve. He had to fit his body in an extremely small space, 20 in. between the power take-off unit and the ground and 36 in. between the truck frame and the ground. He immediately caught the left sleeve of his jacket on the unguarded set screw (rotating shaft) on the power take-off unit. He walked into the lunchroom with his left arm bleeding profusely. While a coworker administered first aid, a call was placed to the Union City Fire Department. Paramedics arrived at 8:37 a.m., applied pressure dressing to the wound, and administered oxygen therapy. Employee #1 was taken to Eden Hospital, Castro Valley, CA, where he was admitted. He suffered severe avulsion of the left arm and complex fracture of the left humerus, among other injuries. He required 12 hours of surgery when his left arm was amputated, with additional surgery later, and a prosthesis.