Fuel Tank Leaks

[eppre]

Better than that would be to have them sell the tank with the oops fittings installed instead of the present fittings.

[daleandee]

*

[Waiex 49]

I thought I would post my experiences today attempting to install the Sonex "oops" fitting in my fuel tank.

I was removing the 1/8" npt fittings for the fuel sight tube. I am installing a Dynon system and no longer want a plastic sight tube on my panel. I was going easy but the molded-in insert spun on me. This is on the passenger side of the tank.

The oops fitting looks pretty nice and the instructions look pretty good. What could go wrong?

Step 2 of the instructions has you drill out the magority of the damaged fitting with a step drill. I got about halfway through this process when the fitting stuck onto my step drill and pulled loose from the tank. The fitting had previously spun loose so I'm not totally surprised by this.

Step 3 has you cleaning up the hole with a 9/16" drill. I got lucky and all the buggered up areas of the tank were cleaned up with one pass of the drill.

Step 4 instructs you to smooth out the hole you just cut. This might be possible on the 3/8" fitting but there wa no way I could even get to the inside surface to dress it down.

Step 1 on the second page of instructions calls for you to thoroughly clean the inside of the tank. Good idea, we don't want bits and pieces of fuel tank plastic swimming around in our fuel system. Easier said than done. The best I could do was to duct tape a thin tube to my shop vac and try to suck out any debris through the 9/16" hole.

Step 2 (second page) has you running a piece of wire through the tank. The oops fitting will slide down this wire to begin its new life in your fuel tank. Think about tying in a second wire to the washer so you can pull the first wire and washer back out of the tank. Routing the wire through the tank was a challenge. I finally pushed about 10 feet of wire up into the tank from the bottom. This gave me a spiders web of wire to catch with a long piece of hinge wire with a hook bent at the end.

I could never finish step 3. No matter how I tried I could not get the new fitting to align with the 9/16" hole and pull through.

The fuel probe happens to be in the same area and I thought things would go better if I removed the probe. The fitting might have more room to maneuver and then I could coax it through the hole.


Well......despite all my best and cautionary efforts the 1/8" npt fitting spun out on me. Not very happy about that. Pretty much the best thing to do at this point is to remove the fuel tank and do this repair on a workbench. I haven't looked into this yet for the exact sequence, but it looks like the course of action is to remove the windscreen and glare shield/instrument panel. Not a fun job but it looks entirely doable.

Good thing my plane is in my t hangar and I have all my shop stuff at hand. I'm finishing up a new engine installation and am also re-wiring the plane so having expanded access to this area is not entirely unwelcome. Working underneath the panel of a Sonex for any extended time is for me a really painful experience and I have a lot of wiring to do.

Looking at the Sonex instructions I notice they are doing this fitting replacement on a workbench. I wonder if they have ever done this job on an in service aircraft.

I would advise anyone in the building of a Sonex to consider installing the oops fittings on all positions before installing the fuel tank into their aircraft.

If you are installing an oops fitting in your flying Sonex my advice would be for you to go slow and be very patient and carefull.

I wish Sonex would either sell an upgraded fuel tank with improved fittings or sell the tank with the oops fittings already installed. Selling an "oops" fitting to fix a damaged fitting is not solving the root cause of this problem. The standard fuel tank fittings are, in my humble opinion, much less than they should be. Builders and owners should not have to deal with sub-standard fuel fittings.

So that's my real world experience with the oops fitting. Time to start on the fun job of tearing my plane apart so I can fix my fuel tank.

Don Bowen
N49YX
LHM

[Waiex 49]

If anyone has removed a fuel tank from an in-service Sonex or Waiex could you please share your thoughts on the best way to do this?

I didn't build my Waiex so I have no knowledge of how the tank goes into the plane, much less any clear idea as to how it comes out.

I am wondering if it is best to remove the windscreen and glare shied / instrument panel and get at it from the top or if it better to remove the tank from below.

Haven't looked at the plans yet but would appreciate any thoughts on the topic.

[rizzz]

I've always wondered how realistic it is to install the Oops fittings without removing the tank.
Anybody ever succeeded doing this?

As for removal of the tank, It should go out the way it went in, i.e. with the glareshield installed but instrument panel removed.
Instructions (to install, not remove) are on the Sonex website:
http://www.sonexaircraft.com/documents/ ... nstall.pdf

[SonexN76ET]

You do not have to remove the windscreen or the glare shield. You will need to remove most of the things in the instrument panel that protrude forward. Disconnect the fuel lines and anything hanging below or to the sides of fuel tank. Then remove the two straps holding the fuel tank in place. Then you will likely have to struggle with the tank for it to come loose and slide down and aft.

If you can figure out a way to fix your tank in place, that would be preferred I believe. People have come up with innovative repairs. Search this site. Dale Williams had a leak he fixed that seemed to work good for him.

Good luck!

Jake

[Major4567]

Possible solution:

I have a set of fiberglass rods that are used for fishing electrical wire in walls and floors called "Fish Sticks". They are flexible and strong.

1. Thread fish stick up from the bottom to fuel cap.

2. Insert top of oops fitting and let it slide down to the bottom

Either:

3. Use the supplied hook with fish sticks OR

3. Get a nut and washer the diameter or little smaller of the fish stick and thread onto the end

4. Pull down on the fish stick until end contacts oops fitting

5. Line up threads and gently pull down until engaged

6. Tighten while applying downward pressure

Possibly a wooden dowel will work also. Fish sticks can be purchased at Home Depot or Lowes in the electrical department. I think the key here is applying downward pressure.

This is only in theory though.

Steve

[rizzz]

You do not have to remove the windscreen or the glare shield.
...

I think though that the windscreen is one of the easiest things to remove. It is a 2 man job but nevertheless, just some screws and nuts.
The thing is that if your panel is riveted in place, you will need to drill those rivets out and that might be hard with the windscreen in place for the rivets on the far left and right. Installing them again afterwards would be just as painful.
For what little extra effort it takes to remove the windscreen it might not be worth fiddling around like that.
Glare shield however is indeed in place when installing the tank so I would imagine the same is true when removing it.

[kmacht]

I'm not sure you have to remove the panel to get the tank out. I had to pull mine and the only thing I remember having to remove other than the tank straps were the control sticks. There was enough room to sneak it between the bottom of the panel and the spar tunnel with the control sticks removed.

Keith
#554

[fastj22]

I've done both, installed the ops in my plane and replaced a tank in anothe Sonex.
The in plane fix is a pain, use a dremel to dress the new hole and a long hinge pin to fish the fitting to the hole from the filler.

To replace a tank, you must remove the rudder peddles, the panel and the tank straps. Lots of work hanging upside down in the foot well either way.

I agree the stock tank fitting design is bad. Sonex should mold in fittings with much larger surface areas to prevent spinning.