Operations was moving ambulance shade frame from to new location using ASM flat-bed truck. Helper climbed on the top of the trailer to unsecure / release the load. IP was required to be inside of the frame to perform this task. After completing the removal of the chains and boomers, one weld on a beam of the frame resting on the truck deck failed from the passenger side of the truck bed. This resulted in a weight shift and allowed the frame to come / roll off of the truck bed (driver’s side). While the frame was moving the IP (still on truck bed) lost his balance on the edge of the truck bed and fell to the ground from 1.6m height on the driver’s side, landed on his right hand, with a wrist fracture