Abstract: At approximately 9:30 a.m. on January 4, 2008, Employee #1, of Albert W. Davies, Inc., was working at a site in Rancho Cucamonga, CA. He was working in a pit close to where a foreman was operating a 35 ton, 1972 Grove RT65S hydraulic boom-type rough terrain mobile crane, serial #39159, with a 34 ft to 136 ft boom. The foreman was using the main four-part line to lift an approximately 200 lb piping spool into the pit. When he extended the boom, the auxiliary whip line two-blocked, then snapped. The headache ball and hook separated at the wedge socket and fell into the pit, fracturing Employee #1's left forearm. He was transported to Arrowhead Regional Medical Center, where he was treated for 11 days. Although at the time of the accident the multi-part main line was equipped with a two-block damage prevention device, the auxiliary line was not.