Hello Pe,
Good news, I was able to remove the broken ends of the broken bolts with a dental probe(pick). I had a spare set of prop bolts and was back up in the air the next day. You are correct, they start backing out after each flight. The 58cc engine is much more powerful than a 50cc. I am so glad I went with the 58cc, it really performs, it just pulls the plane along with ease. I have never seen a 50cc engine do that. I guess the MVVS 58 pro sport is even better. I will seriously think about purchasing the pro sport for my next 50cc size plane. What is the largest size plane the pro sport can handle?
Thanks again for the fast response,

George G. Royal