A friend and colleague was killed, along with the new owner, on the new owner's very first flight in his new (to him) aircraft. 6000 foot runway, with a 1500 foot over run, and the engine burped at somewhere about the 5500 feet from brake release (lots of room to think, and land ahead). We believe that before my friend (10,000+ hour pilot) could intercede, new owner attempted a turn back. It was a two fatal outcome. The investigators stated that the engine was developing power when they crashed - it probably would have flown, if the new owner hadn't spun it.
So, I took over training his several waiting students, and now I've been in hospital for nearly two months - not a turn back accident though. That community will have to find another type instructor...
Never turn back during climbout!