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

Jake,
I have a tendency to really tighten the nut on glow engines. I have never had a problem with a bad one. I don't think the prop nut was the problem. Most often a beginner will flood an engine which will make it backfire and loosen the prop nut. As you continue to try starting the engine it becomes looser. Make sure it is tight and continue to check. Electric starters sometimes make things worse. Get help from an experienced modeler.
Good luck,
EXCAP232

It happens.

happens to me once in awhile. I got a .46FX and if I dont tighten that sucker up, its sure to happen. Use a socket wrench, usually works for me.

Luis

the installer didn't do a very good job,guess if the plane crashes it,s gonna be crappy too.

It's often an out of sight, out of mind problem. If you've got a wooden prop, it'll compress ever so slightly over time. Even if it's something other than wood, it's worth checking now and then. I check mine before every flying session. It only takes a moment, and can prevent an accident.

Yes, I check mine each time before every outing. I'm glad your OK Jake. Ask any of the old timers around you for help.

HTH

Joe

UA,

Sometimes the propnut will come off if the engine backfires, or spits. (a little to rich) This is more true with engines that are new, or newer. no big deal, run in the engine awhile without the spinner, and when it is broken in and you are more used to it, put the spinner back on. I've only had one come off in the air, a Veco .19 (oldie), but had a lot of my engines spit off the propnut when new. More than likely it didn't hurt the engine if you stopped it quick.

Jetts

I guess I don't check my propnut as often as I should.
I have not had one come off since I was training with a OS 40 LA, that was a couple of years ago.
I do put them on tight.
I guess you could put on an extra nut to try to lock it down.

Bill

had that happen to me once when flying my oldtimer. was going to check its dead stick and when i was getting to altitude i here a "plink whaaaaaaaaa" as the prop launched well i got to check the dead stick a bit sooner than i expected.

I acually found the prop later but didnt find the spinner nut (one of those big weighted ones)

I put a new one on a made sure that sucker was tight this time

BTW this plane was sitting around for a few years before I got it and I should have retightened the nut.. oh well lesson learned.

Your prop loosening may be due to the spinner backplate sliping against the base washer. This can be solved by drilling a small hole thru the spinner back plate and the base plate and inserting
a pin thru both of the appropriate size. This stops the "clutch effect" of so many surfaces relighing on friction to hold things together. Some blue locktite on the prop shaft helps too.

This kind of problem is frequently caused by the use of a plastic spinner. If the spinner backplate is plastic, it is more likely to result in the prop-nut coming loose than if you use a spinner that is either (a) all aluminum, or (b) is plastic at the front, but has a metal backplate.

Additionally, make sure you snug the prop-nut sufficiently, and always re-check it after any landing in which you nick the prop.

Gordon