Typical Ppuner argument there Agrajag.
Decry another's argument as unsupported assertions by supplying your own unsupported assertions.
Unsupported? Sorry, but I'm guessing you're new to this topic. The supporting data on my side of the discussion has been out there for a long time by now, and doesn't need rehashing.
So in your own time explain how TBO is achieved in Bell 47-3B1 engines when mixture control was removed from them many years ago.
Don't know; never flown one. But I suspect the default setting was made so rich that the engine couldn't get anywhere near the "red box". I just can't imagine any Bell 47 being equipped with the engine monitoring technology we now have, or that the pilot would have time and spare limbs to make use of it if it were.