When I was with a company teaching on Robinson's we lost one to over pitching. Lucky for the two guys it was closer to the ground and they survived. The machine was sinking the low RPM horn was on and it just dropped down broke and fell over. It had not been out of its weight limits, density limits or in fact any limit and was mechanically perfect (prior to impact) but still on the face of it the pilot over pitched and crashed.
The cause was tense pilot gripping controls to tight. It was for his level of skill a nervous and challenging landing and in tensing up his grip as he pulled in power near the bottom he over rode the governor preventing it from increasing power. As the horn came on he pulled more power and gripped the lever tighter and the rest was history.
Not saying that this happened in this case simply saying it as a learning point for other newer pilots to learn from. All the calculations about temp, alt weight etc would have changed nothing if the pilot himself is going to limit his power available at an earlier point than the mechanics would.