I have a vague recollection of some poor chap who died following a forced landing in a Harvard. The aircraft tipped over on soft ground and he was left completely uninjured hanging upside down in his straps. Unfortunately it took a while for the aircraft to be found, and then longer to upright the aircraft (due to the soft ground) to get him out. In the meanwhile he died - and if memory serves correctly it was as a result of kidney failure due to our kidneys not working while inverted.
I'll dig out the report later to check my memory.