Prop bolts install

[Murray Parr]

Does anyone know how to correctly secure the prop bolts. There doesn't seem to be a way to safety wire the bolts to the Sonex spinner and the bolt grip bottoms out on the threaded Rotax bushings if you use a bolt long enough to protrude the bushing to install a locking type nut on the back of the propeller hub.
I could use fully threaded bolts and a lock nut on the back of the hub but I am not sure if the fully threaded bolts are as strong as a bolt with an unthreaded grip/shank.

Another method I am thinking of is to use Nord lock washers but I am not sure if they would be a positive lock for the bolt

Any suggestion are much appreciated

[GordonTurner]

I am no expert on this, but i am quite sure you should not use fully threaded bolts for this. Get good advice from a reliable source. Sonex or your Rotax dealer preferred.

[Murray Parr]

Thanks Gordon,

Rotax doesn't seem to be very helpful, they seem to just refer you to their installation manual that is vague on this and Sonex has said fully threaded bolts are unsuitable and they haven't come back with a solution other that using Nyloc nuts to lock the bolts but as mentioned above, that won't work with the Rotax bushings being too long for the threads to protrude. I am hoping someone has successfully installed a prop with a Sonex spinner before and can share their methods. I am using the Sensenich prop sold by Sonex so it would be good if they came up with a suitable install method for it.

[garyb]

I used longer bolts on my Rotax powered Sonex and cut some extra threads on the bolts then used Nylock nuts, probably not ideal but it works. Your other option would be to drill out the threads in the bushings and use longer bolts with lock nuts or split pins.

[petep]

Cutting additional threads on an AN bolt is normally considered to be a NONO due to bolt weakening and potential corrosion issues. Suggest you use an adequate length AN bolt and add washers if needed to get the nut seated to the correct depth. As always your mileage may vary!

[Jgibson]

NEVER cut threads on an AN bolt! Cutting produces tiny stress fracture points and all AN bolts have ROLLED threads.
And ABSOLUTELY never use a fully threaded bolt in this application.
For questions such as these, consult 43:13B Accepted Methods and Practices to find out how to do things the 'Aviation' way.

[Murray Parr]

At this stage I am thinking my only option is to drill out the threads in the Rotax bushings and install AN bolts with Nord Lock washers under a Nyloc nut unless anyone has reasons not to do this or has a more successful way to do this. Keep the ideas coming as I am sure others will need this info too

[Brett]

I used the standard metric hardware. I recently installed an engine into my Sonex that had 1000 hours on it that had no issues with prop bolts so I just used new bolts of the same quality.

[Murray Parr]

Brett,
Just wondering how you safety tied the bolts using the standard hardware?

[stroudj002]

Sensenich sells hardware kits that contains the correct hardware and NordLocks. I use a Sensenich 3 blade prop on my Tecnam P2008. It uses Nordlocks and Nyloc washers.

Thanks,

Jim Stroud