Drats, so many requirements, so many requirements. Putting something back where it belongs is just too tough a requirement. Where do I appeal?

For engines .45 and smaller I sometimes use 6-32 machine screws tapped into the nylon mounts. I check them before every flying day and after a couple flights.
In metal mounts I tap and use large machine screws. 632 thru .60 8-32 through .90. Larger gets 10-24 or 32 whichever I pick up in the box of screws, nuts etc.

In all cases where screws are tapped into a mount at least ONE long screw goes through and has a self locking nut and washer tightened up on the bottom of the mount. No engine has ever departed the flying machine since I started that procedure, but a few screws have, especially when I was an ardent pylon racer.

I have a number of the old Fox Alum. engine mounts and use them whenever I can. They were and are the best ever produced.