Abstract: On September 13, 1999, Employee #1 was changing the melting board numbering lights using a Model 40 JLG telescoping boom lift. The boom was fully extended with the basket positioned about 13 ft above the ground, directly under the billboard. The backing of the billboard was made of 0.25-in. plate steel. Once Employee #1 completed changing the billboard lights, he attempted to lower the basket. Instead of lowering, the machine jerked violently upward and crushed Employee #1's right hand between the sign and the aerial basket. The cause of the accident was the failure to maintain and inspect equipment as recommended by the manufacture. The injury was a direct result of poor maintenance, a contaminated up-down switch and a bypassed high limit switch. Employee #1 was hospitalized.