There was a case in the UK many years ago where a private owner had a reputation for looping his own Piper Navajo.
Sadly he perished when both engines detached from the airframe at some stage on the way round a loop. I recall the engines were separate from wreckage of the rest of the aircraft. The AIB were able to compute the amount of "G" that was pulled which was well beyond the normal limits.
Piper Navajo break up in flight
NEVER do aerobatics in an aircraft which is not approved to do such maneuvers.