Get a G10 mount from Bob Hunt and use Locktite.

Ty,i
  On my SV11, I used a double X mount. I put the second behind the firewall and put the screws through it creating a sandwich effect. I used locking nuts on the back.If your motor is front mounted(after re reading this ,I suspect that it is) the above does not apply,then I think the locktite trick mentioned above is your best bet.Another trick that I have used( when I did not have locktite is a little white glue(not excessive) on the threads. It holds well and breaks free when you need to get it off. It seems to hold up well enough to heat and vibrations for our purposes, at least it has for me.

It seems a tad excessive to do maintence after only one flight. I use star washers instead of the split ring type.  I still find it hard to understand how they all came loose after only one flight. There was no vibration or very little while on the ground. But who knows, once it got in the air, no one holding it to dampen any vibs, it just let loose.
As to the Bob Hunt mount, I have 6 of them and have applied one to my Magnum plus. Hope to get it back in the air soon. 
Meanwhile I have taken a break from building planes  and am doing a solid scale model of a Gearing class tin can, the USS Newman K. Perry, DD883. My first tin can, not counting the two I was TDY on. . No weight worries here, no fuel, no batteries, just paint it, glue it, put it on the mantle. USS Iowa next. Only this one floats.

The way things are going, you better have some way of raising that Iowa model after it sinks.....

Screw crush could have been the culprit.

Sounds like a form of infatuation with base motives.