Surely though, if you're idling, and the ali-prop hit rock, the impact to the engine would be similar? - I'd expect a nice dink in the ali prop and probably a small mark on a stainless prop, but I wouldn't expect something pretty fundamental inside the engine to go twang
I know of a couple of people locally who have hit pots at full speed with ali props, and it has been the gearbox that ended up being replaced, not the prop or the bush.
Does anyone else have any experience of a drive shaft failure within the DF140 I wonder?..... I'll trawl through some of the US forums later on....