freakingfast

My Feedback: (3)

BLUE locktite is a godsend and I use it all the time. Engine mount screws, carb screws, fire wall blind nut threads and metal wing screws to name a few.
Just remember to avoid letting red, blue or green locktite having contact with plastic because it can cause plastic to get brittle and crack. If there is plastic like a engine mount, limit the locktite to metal to metal areas such as the head of the screw and engine mount flange or blind nut in the fire wall and screw threads.

It is my opinion that the carb screws should have been loctite-ed from factory, it's a common problem with other brand engines too.
Doing a pre-flight on a cowled engine is not easy, so you learn ways to extend inspection intervals under the hood by making sure things don't shake loose.
The more things that go wrong, the more you (hopefully) learn to how to prevent it happening in the future.

Gray Beard

My Feedback: (-1)

I have seen screws loosen up on a number of engines, several of them the OS carb screws. It doesn't happen very often but it happens. Ken pointed out the need to check and tighten screws after break end and maidens, it's a pretty normal thing to do. About 10 years ago I found the two carb screws for the OS two strokes hanging on a LHS wall and bought the pack, 10 years later I gave them to a friend after both his fell out of an OS .55AX. He never tightened anything after break in and his engine was so cowled you couldn't check anything anyway.
For myself, I haven't ever lost one. I run in the engine then just tighten the screws up while the engine is still warm. I never use any locking compounds because I have had problems in the past removing screws when needed. I don't check for loose screws often but every once in a while when I think of it I go through them.
New engines expand when they warm up and the screws loosen when the engine cools off. It's an operators problem if these screws loosen up, not the manufacture. I will be breaking in a new engine this week, after it is run a time or two I will tighten every screw on the engine. It's a must!!
In this case it will be an SK engine but the make doesn't mater at all.

freakingfast

My Feedback: (3)

A lucky man.

I've had some applications if loctite wasn't used, you could tighten as much as you dare and it would be loose before your out of fuel. Yes things were in balance. This is usually on higher than normal rpm situations. K&B outboard engines where the engine wants get off the lower unit, pylon racing engines, Viper Quickie 500 wing screws to name a few.

Never had a problem with removing a fastener using blue (removable) loctite if the fasteners or tools weren't rounded off to start with. Red loctite is a different story!

Where needed, blue loctite is just standard operating procedure for me on all my planes, trainers to 180 mph deltas.

Just one less thing I need to worry about...you see, I'm not a lucky man...I know Murphy's Law quite well.

Gray Beard

My Feedback: (-1)

I started using Never Seize on my engines again, I think tightening the screws when the engine is still hot is the key for me, not just luck. I use nothing on my mufflers either and haven't had one come loose. I do use the Blue LT on my motor mounts though.

exracer

My Feedback: (1)

I'm pretty new to flying and just after my trainer and I flew 6 flights together we landed. This too was a NexStar with a OS 46 and when I went to do my solo flight we could not get it to stay fired up. I had a few guys look at it and made many adjustments to the neddle valve, but still would not stay running. Well I went home with out the solo flight. When I got back to my shop I went to check the fuel tank and clunk and replaced the fuel lines. As soon as I pulled one of the fuel line thats when I found that both screws were missing from the carb. I was luckey I did not get off the ground. Sorry to here you lost yours in flight. I check all the screws now before flight. No never seize or Loctite just righty tighty.

opjose

It's the Pilot's ( not the manufacturer's ) responsiblity to make sure the plane is flight worthy.

Sad to hear of the problem, but this will not be the last time something like this will come up if you keep flying.

Not only should you check the carb screws but you should check the engine mounting screws, muffler screws, servo screws, piston head cap screws, engine back cover screws, etc.

All of these components are being subject to vibration, heating and cooling cycles which will cause the screws and fastners to loosen over time.

If you go back and check the engine's cap screws I'm SURE you'll find that they are loose now! A good 1/2 turn or so!!! Go ahead and check.


You should remove them one at a time, apply a bit of locktite to the screw, then warm the engine with a heat gun before re-inserting the screw.

Every dozen or so flights you should recheck tightness again.

bruce88123

And when Opjose says "you should check the engine mounting screws" he means the screws that hold the engine to the mount and the screws that hold the mount to the plane if applicable. Some planes just use hardwood beams or other means permanently attached to the plane. There you would check for deterioration of the material.