Spinner Assembly Came Apart While Engine On!
 

I'm wondering if any of you have experience with the OS prop nuts being crappy. I had the engine finally running well enough to start to break it in, when the entire freaking spinner assembly, prop washer, prop nut, and propeller separated from the engine as I increased the throttle. As you can imagine, it scared the hell out of me. Of course the engine over sped, so the engine stopped. The engine is a 40LA and am running a 11 X 5 prop.

The only thing I can guess happened was that the prop nut became loose or stripped. How tight should the nut be? I thought it was pretty tight, but you never know. Should I use a torque wrench? I really don't know. Any help you could give me, I would appreciate.

Thanks,
Jake

Spinner Assembly Came Apart While Engine On!
 

You don't need a torque wrench to tight prop-nut. But it should should be torque hard enough where you need to to use a towel between your hand and the prop to hang on to it. Does the prop backwasher still have swirling grooves on them? The only other way where the prop-nut come loose is when your engine is running backward. You may have started the engine in the right direction, but at low idle it ignited before top-dead-center and send the crankshaft turning in reverse. I have seen this problem before when non-bearing engine such as the OS LA being run with high nitro and standard long plug. Try shorter plug. Try 10% or 15% nitro fuel.

Spinner Assembly Came Apart While Engine On!
 

On my .46LA I added a lockwasher under the nut and have not had a problem since. My spinner would also loosen especially when using one of the nose weights. A little loctite may also be helpful. You could also use a second nut if the shaft is long enough.

Spinner Assembly Came Apart While Engine On!
 

If you run too lean, you will cause preignition, and you will loosen the prop nut.

Les

Spinner Assembly Came Apart While Engine On!
 

beginners usually do not tighten the prop nut enough. You really have to crank it down. The little hobby wrench usually doesn't give enough leverage.

Spinner Assembly Came Apart While Engine On!
 

I will presume that you are using a non- wood prop

I don't use a torque wrench , but I really crank the
nut fairly hard.

If you use a wood prop , (I prefer them)you MUST
check it before every flying session ,it will be loose
because the wood compresses.

What you experienced is why you shouldn't be in the
prop arc.

Regards
Roby

Spinner Assembly Came Apart While Engine On!
 

i've not had it happen, but spinners, newbies and starters are not a good combo. also the engine flodding can do this. rare while running.
however, if you look at.. erm.... crash pics on www.rcflyer.fsnet.co.uk you can see what happens when a spinner explodes