When I purchased my trainer I ordered a whole list of things to put it together, one of those things being [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXK306]thread locker.[/link]

Well, for some reason, when I was assembling the ARF, either because I forgot or felt it really wasn't necessary I skipped using the stuff.

Boy am I sorry now. My nose gear bearing bolts came loose a few weeks ago, and even though I have the thread locker in the flight box, I figured I'd be okay replacing the steel cheapy screws that came with the nose gear with black cap screws someone had at the field, tightened down securely.

Guess what? Yesterday after I was done flying and was cleaning the plane, I see one of the four caps crews almost completely unscrewed and another one loose! I tightened them down, again, forgetting to use the thread locker.

Prior to that, when pulling the wing off, I noticed one of the servos had two screws missing, both on the same side! Boy was I lucky nothing happened during the flight! I found one of the screws loose in the bottom of the fuse but have no idea where the second one went. I just came back from the LHS and have a bag of servo screws and brass grommets. This weekend I'm going to take the plane down to the shop and remove all the screws in the plane and apply thread locker before I screw them back in place.

Just a friendly reminder to all to not make my mistakes and use the stuff! It's still amazing to me how the vibration from the engine can actually unscrew a long screw over a relatively short amount of time!

Thread lock is good for most of our metal to metal connections. I should not however be used on work or plastic connections, so I'm a bit curious about the servo screws you said were missing. Is the servo screwed into wood/plastic, or a metal block?

Wooden servo trays that came installed in the Sig Kadet LT-40.

cap,

thats really strange i have never had any servo screw come loose before let alone back all the way out did you CA the screw holes after you put the servo screw through then pulled them out ?

it hardens the wood around the screw and makes them hold better.





bassman

Don't use theadlock on the wood, it won't work in that application. Any metal to metal connection however could benifit from the locker with a few expections. If the servo hold down screws are backing out of the wood try to harden the holes with some CA then see if the threads grab better. If that doesn't help and the holes are really wallowed out you might be able to find different screws that work better or you can also glue a toothpic in the hole and then redrill, etc.

Obviously be sure to let the THIN CA dry completely before putting in the screws or they will never come out. Like the others said, do not use thread lock on plastic. It attacks some plastics and makes it brittle.

And don't use threadlock on tapped holes in the fiber type of engine mounts. It softens the material and allows the screw threads to simply pull out. And yes, this is personal experience.

Ken

And do inspect you planes every now and again before you fly them. We all tend to forget to do this, {{Well, Not Me}} It can make ones face turn colors when you are at A fly in and your engine falls off when starting!! No, it wasn't me but I was the one that inspected the plane the day before, did I miss something or did the screws fall out in A day of flying??? Sweet Mystery of Life!!!

Thanks for the tips. I really learn a lot from you guys.

As I don't think the servo screws are holding that tight, I'll CA some toothpicks as suggested and drill the holes smaller, then ca the new holes, let it dry and mount the screws again.

It is always a good idea to glue some ply from scrap under the servos bay just where the servo screws are placed, the extra wood will give a good bite to the screws.

I personally don't think i've ever had bolts or screws come loose during normal flights on glow planes from .07 to .46, but i do make sure my props are very well balanced and always use spinner prop nuts ( never plastic spinners ) which might be attributed to the lack of vibration ( which loosens screws and bolts quite well ).

I think you need to look very closely at what microsprint9 is referring to. Do not just tighten the screws/bolts that you find loose, but find out why they are coming loose in the first place! They should not be doing that.

Good luck

Earlier this week I was helping a friend peak the engine on an Ultra Sport 1000 and the plastic spinner actually exploded at the max rpm !! That was a first for me.


Buy a quality aluminum spinner!

PhatBob that actually happened to me just a week or so ago. Thing just exploded. May have been not balanced just right but dang that was dangerous. Also was working on a 125 when i guess it backfired or something and the prop shot 50ft. across the yard. I suppose that is why you check them there bolts and nuts. Used a metal detector and acutally found the prop nuts. Just glad i was behind the prop at the time.