I installed a single bolt prop adapter on my DL 50 this last summer. Since the bolt heads are tapered, there is no way to get a lock washer behind them.

I think there are only 2 things that could cause this. The bolts getting loose, or the bolts used to fasten the adapter are not of the right grade/hardness. I know Hobby King sells these, very cheap. The bolts probably are too!

The instructions that come with the Valley view unit are very specific about type of thread lock and torque. I wonder how many that have broken were either the Hobby King variety or the directions were not followed properly?

It is imperative to get the original prop stud below the thrust washer on the engine. If the new prop adapter makes contact, it will not seat properly and break.

Jodi, from Valley view commented that he had only seen one failure and this was the reason why.

Great service by Valley View is they will install this for you when you buy the engine. That is a great deal as it is not the easiest thing to do. I think it took me around an hour to convert mine.