DeferredDefect

I remember reading a "Safety First" column in a 1980's "Model Aviation", which was about a club that flew model aircraft behind a movie theatre. No, these were no 1/2 A single channel models, but 60 sized sport models that they were flying above a mall!
I think there was also something about one of them balancing propellers by firing up the engine an grinding the prop on the sidewalk.
Oh boy. What could possibly go wrong?