Hello Pe,

After two flights on my Aeroworks Ultimate, all the prop bolts(6) broke off in the prop drive of my Evolution 58gx2. The center 10mm nut was tight. It has a Xoar 24x10 prop. I did use a small amount of blue locktite on the 6 propeller bolts. I have a three year old 45gx2 and never had this problem, although the bolts are larger. Could you tell me what could have caused this problem? Also, is the prop drive pressed on? I was thinking about replacing it myself.

Thanks,
George G. Royal

I have never used Locktite on prop bolts. Over tightening the bolts can surely break them so use small hex driver with short handle. Blue locktite can be removed with heat, but because of magnets in the hub that maybe not possible. If you have powerful soldering iron with large head, try to warm them up after drilling hole to the middle of the bolt. Replacing the prop driver certainly is a simpler solution than drilling all bolts out.

The prop bolts must be tightened with regular intervals because the prop hub relaxes, especially on wood props. For that reason, Loctite is not a good idea. I torque M5 bolts to 3Nm on wood props, 5Nm on carbon props.
The 58cc bolts (M4) can be torqued 2.5/4.0Nm (wood/carbon)
Failure to do so will cause the prop bolts to break sooner or later.

The central bolt keeps the hub on the crank, and should not be over-tightened. The thread is M10x1, and provides tons of clamping force if just tight. The prop assembly can be used to pull the taper loose from the crankshaft. If you do not feel confident, leave it to a qualified person.

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

If the bolts loosen (not back up) after each flight, check your prop properties as well. If the wood is not dense enough, it will do that. Choose dark colored wood when buying a prop. Carbon props are better and keep the initial torque quite long. Still need to be checked every now and then though.

The 58 will power my 40 lbs piper cub with ease and power to spare for towing. If you want to fly 3D, think 20 - 28 lbs. The prosport is about10% more powerful.
Tip:
MVVS currently has Limited Edition engine on sale, (prosport engines with special Black/red anodize)