The pilot reported that during the turn around at Brewarrina, he had not stopped the engines and the freight was placed in the aircraft through the rear cabin door. The cockpit door was not opened during the turn around. The pilot said he carried out the pre-takeoff checks and backtracked on runway 21 to use the full length of the runway for takeoff. After becoming airborne and establishing a positive climb rate he selected the gear up. Seconds later the pilot heard an explosion-like sound and noticed the cockpit door had opened. The pilot said his initial reaction was to grab the door and attempt to close it, but due to the aircraft being in a critical stage of flight he concentrated on flying the aircraft. Judging that he had sufficient runway ahead of him to land the aircraft he closed the throttles. The pilot said that after losing considerable height he realised the gear was not down, so he immediately applied full power. The pilot flew the aircraft away from the runway surface and carried out a 500 ft circuit. He subsequently carried out a normal landing, and taxied clear of the runway.
An inspection of the aircraft revealed that both propellers had contacted the runway, the step behind the right-wing root had been bent up, and the ADF sensor antenna had also been bent. The pilot said that he was certain that the cockpit door had been positively locked before the previous departure from Bourke, and that the locking handle had not been moved since that time.