Folks,
I bought and assembled the Tower Trainer 40. It came with a regular fuel bottle and attachments. I attached the clunk, inserted the bottle into the fuselage and assembled the rest of the plane. After running the engine to adjust the needle valve I noticed a loud rattle inside the plane. The clunk had come loose!!

This is with only running the plane statically on the ground with no flight!!

I had to remove the engine and many parts to get the tank out and sure enough, it was loose. As I examined the clunk, I found that it would pull loose easily from the fuel tubing. I went to my stash of bits and got an alternate clunk and attached it. As I pulled this clunk, it wouldn't come loose and started to stretch the tubing. This one was on solidly and I re-assembled my plane.

So ... when attaching clunks, make sure that they stretch the tubing when you give them a pull or they may come loose. I guess I was lucky to catch it before a flight.

Neil

The replaced clunk was the Dubro Fuel clunk ... see:

http://www2.towerhobbies.com/cgi-bin...?&I=LXAHE9&P=7

This has two 'ridges' and not just the single one that came with the basic bottle.

Is that what all the teens you see with their hand on their crotch are doing, pulling on their clunk to see if it will fall off?

I always change the supplied fuel tubing that comes with most tanks to go from the clunk to the tank plug. It's thinner stuff, and usually tears, even if the clunk stays on. I use regular fuel tubing, and also use a small plastic zip-tie to hold it in place. Haven't had my clunk fall off yet.

But you might go blind

And the zip-tie hurts like hell, but the gals seem to like it.

Unbelievable ... I maidened my new plane yesterday and ... once again ... my clunk had fallen off. I had assembled the fuel tank a few days ago and, trying to ensure that the clunk would not just fall off again, I had wrapped some fuse wire over the hosing and barb to be certain it wouldn't come loose. What I appear to have done this time is to tighten the wire too much and the result was that it partially cut through the tubing. During flight, the tubing separated from the clunk at the wire portion ... basically I garrotted my clunk.

The dumb thing was that the clunk had already passed my 'pull test' but I wanted to be safer than sorry. The fuel bottle mouth is only 'just' wide enough to get the clunk through ... and now that it is loose inside the bottle, there will be no way to get it out short of cutting the bottle open. I now use a new bottle.

Neil

Use a small plastic zip tie as mentioned above to secure next time. It will not cut the tube, and you can tighten it right up.

I have never needed a nylon tie . Just make sure you are using the right sized clunk and tubing ..If you use large tubing and a small clunk it will fit loose and fall off . I do use barbs and ties with tygon lines on gassers ..

A zip tie works well. You can also cut a short piece of tubing as a doubler.

David