XT 912 tundra fuel valve

[Guest rohayes]

Hello all,

 

We have an Airborne XT 912 Tundra. Great aircraft with a small annoying problem. The fuel drain valve leaks if you don't pry it down with a screwdriver or something. The valve can also leak when it comes into contact with the fabric shroud around the base.

 

Does anyone know what size and thread this valve is?

 

I have seen better valves available, and I'd like to know the correct size.

 

I don't want to drain the tank and have it sitting empty for a week or more waiting for a replacement to turn up. Any suggestions as to replacements is also gratefully received.

 

Cheers,

 

Bob

 

 

[BLA82]

http://www.airborne.com.au/images/manuals/XT912IPC1_2.PDF

 

you might be able to find it here

 

 

[Guest rohayes]

Thanks for the reply.

 

The parts manual has a drawing of the valve, but not the thread size and specs.

 

I'll keep looking!

 

Bob

 

 

[Tracktop]

Hi Bob

 

My advice - Don't keep doing what you are doing.

 

Mine also was the same and I have been pulling and twisting for some time now after checking the fuel, to stop the dripping.

 

Today while getting ready to fly I refueled and did a fuel drain check then I decided to tie the back of the fabric shroud back to the tiedown loop and rear strut in an effort to keep it clear of the drain valve. While doing this the drain valve was still dripping from the test so I did my usual twist and pull and the plunger came completely out.

 

Of cause Murphy was helping me and I dropped the part in surprise, so there I was little (really old Fella) boy with his finger in the dyke stopping the flow and unable to reach the loose part on the ground. Did the dash and grab and pushed the plunger back in the hole and it mostly stopped the flow without too much loss of fuel.

 

Really pleased it happened then and not in flight as it most certainly would have dumped the fuel without notice and resulted in an engine out - I would much prefer to just practice them with a running engine.

 

Drained the fuel ( an easy job with the faulty valve) and then removed the valve.

 

The top O ring had suffered under my attempts to stop drips in the past and the spring retainer was gone. SO ENDED MY MORNING FLYING LESSON bugger!

 

Lucky Airborne is not to far away so headed off an got a new one, then back and reinstalled in time for a rescheduled afternoon lesson.

 

Airborne's suggestion for stopping a drip is to continually operated the drain valve as it is usually caused by piece of foreign material from the fuel lodging in one of the small holes or under the O ring. Repetitive operation usually dislodges or shears the foriegn body and flushes it free

 

So in summary from my experience I would suggest it's a cheap and easy fix but requires draining the tank.- Just replace the 2 small O rings that are probably now damaged, But do it before you loose the retaining spring an need to buy a new valve either similar or different.

 

Took some pics of the valve if that helps. Checked the thread size but couldn't ID in the limited time I had available ( though I did check it against a few different threads I had at hand)

 

Hope this is of some help

 

Ray

 

 

 

 

 

[Guest rohayes]

Thanks Ray, that's been very useful! I must admit it did not occur to me that the valve could come out completely. I have been ginger with it but will be even more so now. Some of the other trikes up here have modified their valves to drain away from the original place, mostly via a piece of plastic hose and a valve that locks open.

 

I will ring Airborne tomorrow and order a new valve!

 

Thanks again

 

Bob

 

 

[Tracktop]

Hi Bob

 

By all means order a new valve, but it is most likely you just need 1 or 2 new small O rings.

 

I needed a new valve because the small steel retaining C ring at the top was missing.

 

Just be careful when dis-assembling that you don't loose any parts.

 

Thinking about it now I know what it looks like and how it operates I think when you pull the plunger down in an effort to make it seal you (me) shear the outer edge of the O ring off. The plunger then drops a little lower with the remaining part of the O ring sealing inside the hole rather than on top as pictured. In this situation the steel C ring probably stops the plunger coming out by seating where the O ring should seat.

 

To make matters worse the loose sheared off bits of O ring probably cause more problems with poor sealing compounding the problem.

 

After writing this I think I might measure the distance the plunger travels ( or hangs out) as a means of condition monitoring the valve as I would expect the valve to protrude further out ( have more travel ) if the top O ring is faulty.

 

If you purchase a new one you could still recondition the old one as a spare.

 

By the way the string seems to be keeping the soft shell away from the valve nicely, and its really nice to have a valve that seals easily again.

 

Ray

 

 

[skeptic36]

Hi guys,

 

I wonder if the O rings in the valve are rubber i_dunno. If so it may be worth while replacing them with Viton O rings. I have a pressure relief bypass valve in a hydraulic system which had to have the O rings replaced regularly, somebody put me onto the Viton ones and I haven't touched them since.:thumb_up:

 

Regards Bill

 

 

[cscotthendry]

Hi All:

 

I've just re-read this thread and something occured to me. When I check my fuel I always wipe my finger gently across the bottom of this valve and it always comes away wet with a little bit of fuel. However, after a couple of seconds and a couple more wipes I don't get any more fuel on my finger. Looking at the design of the valve, I think it may be possible that what we're taking for a leaky valve is just a bit of fuel that has remained in the valve due to capilary action between the centre part of the valve and the body.

 

My suggestion is that instead of continuing to fiddle with the valve by twisting and plunging, that you just wipe your finger gently under it a few times to coax the remaining fuel out of the valve, then leave it for a minute or so. Then wipe your finger under the valve again (without pushing it in) to see if there's still fuel coming out.

 

I'd be very interested to get some feedback on this suggestion.

 

 

[Tracktop]

Agree with what you say about the little bit of wet.

 

But when they get a bit of foreign stuff in them they drip and drip and drip until cleared.

 

And as a feedback, since draining / flushing my tank and replacing the valve, all has been 100%.

 

Do the drain check, inspect sample, put the tester away, come back and check for leaks. ALWAYS DRY - one happy camper.

 

 

[cscotthendry]

I assumed everyone is always doing this, but the comments about contaminants in the tank suggests otherwise.

 

Whenever I refuel, I always use one of those funnels with the really fine strainer in it. There are some that have what looks like flywire for a strainer and they're not the kind I'm talking about. The one I use has a strainer that looks about the same pitch as my wife's coffee filter (not the plunger type but the 2 piece cup shaped strainer). I feel that anything that gets past that strainer in my funnell, is probably not going to be big enough to jam the drain valve.

 

Even my instructor fusses over the valve. I'm beginning to believe a lot of the problems come from fiddling with the valve rather than the valve leaking.

 

 

[Tracktop]

Even though airborne clean and flush the tanks out thoroughly before fitting them. I believe after a month or 2, small bits come off the tank side from manufacture. The cause of our grief. When brand new, and other I have looked at, had clean fuel checks. As time goes by stringy type clearish small particles begin to appear.

 

During my drain valve replacement, I completely drained the tank and then ran a bit of extra fuel through as well. After doing this I no longer get particles in my fuel drain check, and my valve doesn't leak at all.

 

Other than the small amount of fuel that was in the tank when I picked up my trike, every single drop of fuel that has gone into the tank has gone through a Mr Funnel.

 

This funnel has to be the ultimate in funnel filters, it even has a water trap though being careful where I buy my fuel from I have not found any water to date.

 

I do also use another one at home for diesel refueling if I use a drum for refueling. I often get water filtered out of that one.

 

Tools & Equipment :: Mr Funnel 8" Fuel/Water Funnel - Aviation Pilot Supplies Shop | Flight Gear | Aircraft Instruments

 

Yes my instructor used to fiddle with the valve as well. They are usually in a worse situation as their trikes are regularly replaced and usually always new.

 

My recommendation is after a couple of months - Dump the fuel out and replace with new. You don't need to waste it - put it through a Mr Funnel into you car / mower etc

 

The other thing I have done at others suggestion, rightly or wrongly ( there are varying opinions on this ) is to only use BP Ultimate.

 

There are some other posts on this but in a nut shell the theory is.

 

Ultimate is a better quality fuel and will not have any ethanol traces in it so water in the fuel is less of a problem.It is claimed that the octane rating of fuel quickly diminishes with time so starting high means by the time it is used is has a better chance of being in the correct octane spec. Start with a fuel with an octane rating close to spec and you can only go down and out of motor recommendations. Be careful if you use Shell 98 ( or their resellers) brand fuel as it has compounds in it may cause an interaction with plastic clear tanks where exposure to UV exists. With non clear tanks or no UV exposure Shell is fine - according to what I have read elswhere .

 

 

[cscotthendry]

Ray:

 

Thanks for the heads up about Shell fuel. Can you point us to the research you did about the additives in the Shell fuel? Up until now, I had been using Shell, as it's the nearest station to my flying field and I had a bad experience with a BP fuel many years ago, BP Zoom.

 

If the Shell fuel is going to deteriorate my tank, I'll not use it again.

 

edit:

 

I did find this about adding acetone to fuel.

 

http://www.pureenergysystems.com/news/2005/03/17/6900069_Acetone/

 

 

[Tracktop]

Had a quick look around

 

http://www.recreationalflying.com/forum/trikes/44860-regular-unleaded-912-a.html

 

this was one thread that was happening at the time but there were others with more detail.

 

interesting article about acetone :thumb_up: