Also not mentioned is cam shaft failures on chieftains, these engines rarely make TBO of 1800 hours any more because the lobes on the cam shafts break down causing the engine to not produce full power.
I would dispute that. The late Tony K always maintained that the Chieftain engine would make 1800hrs TBO is maintenance was done properly.
For that to happen is really one of two things, manufacturing error, or re using parts in cheap overhauls or just cheap overhauls.
Quite.