The Bristol 170 aircraft took off at about 08:25 on a non-scheduled flight from FOX to CAM D with the pilot-in-command, co-pilot and flight engineer on board; the chassis and engine of a five ton dump truck was carried as freight. About one minute after take-off the pilot-in-command called the control tower and told them that his load had shifted to the rear. At 08:27 when the aircraft was approaching the end of the downwind leg it was seen to assume a climbing attitude, fall into a spin to the right and crash to the ground. Also five seconds after the impact the aircraft exploded and caught fire. The three crew members were killed and the aircraft was destroyed. PROBABLE CAUSE: “The truck, which was not properly secured, broke free, probably during the acceleration of take-off and slid to the rear of the aircraft, causing the centre-of gravity of the aircraft to move considerably aft of the maximum permissible aft limit. While attempting to return to land the pilot lost control of the aircraft which stalled, went into a spin and crashed.”