Sight tube

[Guest Redair]

Greetings each, I am seeking help regarding the installation of the fuel level sight tubes. I have heard of an incident where the sight tube has leaked severely at the point which it connects to the brass fitting in the tank, (that is to say, between the tube and fitting, not between the fitting and the tank) this was a new installation, not an old tube which had just failed, and resulted in a lot of mess and some damage.

 

Has anyone else experienced the same problem? And what is the correct method for attaching the sight tube to the fitting. The manual is not very clear at this point, and has resulted in several different interpretations of how it should be done, some by using bigger clamps, some by fitting rubber tube over the sight tube and even by reshaping the brass fittings.

 

Any advice would be most welcome.

 

Thanks, Redair.

 

 

[markendee]

I fitted mine as per the manual and have had no leaks in 145 hrs flying (seventeen months)

 

BTW I left the carpet covers off the wing roots (they were pre cut for slatted leading edge not the VG model) and am glad I did. It is easy to look in and see the fuel level in the opaque tanks from the pilot seat.

 

Only problem I have experienced is the O ring on the fuel check valve letting go and dumping full tanks onto the ground while hangared. Perhaps replace this with a better quality one from the off. ($1.50)

 

If I were to build another I would fit the fuel tank cover skins with good quality rivnuts so I could easily get in there and inspect/tighten everything each 50 hour service.

 

Mark D

 

PS Come to think of it maybe I did use two differing diameters of tubing. I will check it out and get back to you Redair.

 

 

[Guest Redair]

PS Come to think of it maybe I did use two differing diameters of tubing. I will check it out and get back to you Redair.

 

Hi Mark, thanks for the reply. I had already closed up one wing before I heard about the problem, and I had installed the sight tube straight onto the brass fitting with only a hose clamp. However, I don't want to go ahead and try to fit the other one the same way, in case it leaks. If a length of rubber tube has to be fitted over the end of the sight tube before attaching to the brass fitting, then I can do it before closing up the second wing. I'll have to drill out the inspection panel of the first wing to correct that tube, but at least it isn't painted yet. Sadly I have very little room to work in, so the first wing is hanging on the shed wall, like a big aluminium picture, and I don't have enough space at the moment to be able to get it down and try filling the tank with fuel to see if it leaks.

 

Also, thanks for the tip about the fuel drain "O" ring, I'll get on to that too.

 

Regards, Redair.

 

 

[markendee]

Red,

 

Shot out to the Tonny Aviation and Aircraft Service Centre Complex to check out my set up. It is amazing how the memory suffers as we get on. Looking at my fittings didn't bring the memories flooding back as I hoped.

 

It appears I fitted oversize tubing over the sight tube, enlarged the holes through the rib and clamped both to the fuel tank fitting. The larger tubing protects the sight tube and gives the whole shooting match much more bearing surface for the clamp to do it's thing.

 

Don't recall the thinking process behind all this but it is as tight as a drum and I suppose the proof of the pudding............

 

Maybe I'm cleverer than I thought! (doubt it though)

 

Hope this helps.

 

Mark D

 

 

[Guest Redair]

Mark, to quote Mr. Burns.... Excellent! That sounds like a plan, looks like I will be ripping the first wing apart, (when I get some room to move) to do the mod. The second wing will get it first.

 

Thanks again, Redair.

 

 

[Guest milton56]

Hi Redair

 

I had a problem at first with my sight tube at first, so I used a bit of Stag sealant and this has solved the problem. Also I used ruvnuts on the tank access panels and and by doing so will help later on in inspecting and changing tubes etc.

 

Regards

 

Milton56:thumb_up:

 

 

[Guest Redair]

I used ruvnuts on the tank access panels and and by doing so will help later on in inspecting and changing tubes etc.

 

Regards

 

Milton56:thumb_up:

 

Thanks for that, I might go with the rivnut idea, as I am going to have to drill out the rivets to remove the panel on the first wing. Does seem like a lot of rivnuts though.

 

Redair.

 

 

[Guest milton56]

Hi Redair

 

Just a little more on the rivnuts. I bought 100's + as I used them on the roof panel to wing so I could take the wings off without drilling out rivets. I did this mainly because my runway at home has not been finished and had to trailer the plane to Rods Bay and reassembled it at the airfield.

 

Regards Milton:thumb_up:

 

ps Don't rivnut the main spar area on the tank cover, use the large rivets.

 

 

[Guest Redair]

Thanks Milton.

 

Redair.

 

 

[Ron Hoey]

Fuel tanks inspection

 

Hi Redair,

 

I went a different way with the fuel tank inspection problem.

 

I bought 6 round inspection plates (I think from Aircraft Spruce) and installed them on the fuel tank access covers (2 each on inner and 1 on outer tanks) immediately below where the potential problems are, namely the inlet/outlets. Hopefully this will give me enough room to fix any problem which may arise.

 

Good thinking un-tacking that first wing if you think it may be a problem- it will save you many sleepless nights.

 

Regards,

 

Ron.

 

 

[Ron Hoey]

Fuel leak

 

Hi all,

 

Well, if ever there was proof that these forums are gold, this is it.

 

After my first test flight I noticed a fuel leak from my left tank.

 

Having installed the inspection plates as described previously I accessed the problem.

 

It was exactly as Redair's original post. I had connected the sight tube directly to the brass fitting and it was leaking.

 

However, having read Mark's solution I was able to fit a piece of rubber hose over the tube and on to the fitting, with a dry result.

 

Thanks guys.

 

Ron.

 

 

[markendee]

That'll be one cold beer at Natfly Ron.

 

Just kidding, (two beers) glad it fixed the problem.

 

Mark D