I can remember way back about forty or more years ago, the AMA mandated that all engines must have a safety nut of some fashion to cover exposed threads. I am not dreaming this - it was fact at the time. That rule was so ingrained into my brain that I never fly an airplane without a round spinner of some type on it, and have been doing so for many years. I gave up competition flying years ago also, and haven't read the rule book since, but you won't see me flying without a spinner regardless of what the rule book says today.

It just makes good sense to cover those exposed threads with a spinner of some sort, and so I agree with Mr. & Mrs Education. It's the right thing to do.

Since safety is always our number one concern - what's the use of arguing? Just do it! It's that simple. When you hit somebody with your plane, you can argue in court that you were really safety concious all you could be - "See - my plane had a spinner on it, and it's not even in the rule book as being required. If I wasn't safety concious, it wouldn't have been there."