Abstract: Employee #1, a crane operator, was using a Grove TMS-540 crane, serial #220945, to remove a 910 lb Wacker power trowel, model CRT 46 KHN, serial #751501067, from the third floor of an office building under construction. The crane boom was fully extended to 115 ft, with a 30 ft extension, a 6,000 lb counterweight, a 300 lb ball, a 45 degree offset, and single part reeving. The crane outriggers were fully extended and the estimated boom angle was 55 degrees, with a 95 ft radius. The crane's rated capacity in this configuration was 1,770 lb. The stabilizer pads were on pieces of 4 by 8 hardwood, on top of which were varying lengths of haphazardly stacked 2 by 4 SPF (Spruce-Pine-Fir) that were not level. Employee #1 heard a loud pop, after which the crane immediately tipped over. Apparently, as the load was passing the right front outrigger, either the 2 by 4 blocking or the outrigger failed, causing the crane to overturn. Employee #1 sustained multiple contusions and abrasions, for which he was hospitalized. He had not been required to pass a practical operating examination for this crane. Another causal factor may have been the failure to compensate for the boom deflection. The employer was cited for apparent violations of 29 CFR 1926.550 (b)(2), referencing ANSI b.30.5.