Originally Posted by
EXDAC
I have taught engine fail turn backs and you really have to know the aircraft to know if it is possible. In the PA-28-180 and AA-5A I have done them from 300 ft AGL with engine idle. In my constant speed prop Carbon Cub 500 ft was the absolute minimum. I would not attempt a real turn back with much less than twice those altitudes.
Careful there, performances with an engine at idle versus a stopped or windmilling prop are very different.