An RAF colleague of mine set off in a Puma for a task. He returned a few minutes later, complained bitterly to the ground crew chief that the aircraft was u/s. He was allocated a second aircraft and the "lineys" were sent into the hangar to tow it out. He signed for the new aircraft but before it was towed out he went back out to the first one and took off in it again! Best thing was, the crewman was still in the first Puma, he thought they were OK to take it after all! My colleague thought he had swapped all the kit over to the new one.