Fuel guardian sensor leaking ! (with pictures)

[Pilottonny]

Hi all,

I am coming across a very strange problem. I will be painting the wings in a week or so. Because I will paint with the tanks on the wings, I removed them one at a time and put 20 ltr. of Avgas in, just to be absolutely sure that they are tight and there is no ?weeping rivets?. I left the Avgas in for over a week and rotated the tank every day or so, to make sure all sides were immersed for a couple of days. Because I closed off all the connections, pressure built up inside the tanks (like what you get in jerry can). The left tank was fine.

Today I put the right tank back on the wing and noticed that fuel was leaking from the ?Fuel Guardian?-sensor. In the first picture you see the left sensor covered in Pro-seal and on the wires. (Tanks primed after assembly).

In the second picture you see the right sensor with the pro-seal removed. The fuel was actually leaking from the sensor itself!! There is no cracks, but the fuel is leaking from where the wires exit the sensor, not from between the sensor and the tankrib. How strange is that??

After I released the pressure by opening the fuel cap, it stopped leaking. Obviously, during normal operation there will be no pressure on the tanks, just the head of the volume of the tank and any additional G?s from maneuvering. But I do need to make sure the sensor is absolutely fuel-tight.

I checked the sensor with an extension lead and it works perfect. Anybody any idea how to seal it? The pro-seal obviously does not ?attach? to the wires enough to seal them. Maybe Epoxy around the wires? And than seal in with RTV? Any other thoughts?

Thanks in advance for your replies.

Regards, Tonny.

 

[Pilottonny]

Never happened before!!??

Just received an Email from Rich, from Aircarftextra's: guess what?: "Never seen this before"

Any of you had this problem? Or anyone know how to seal the Tefzel/PVC wires? (tank sealant does not stick to it!)

Regards, Tonny.

 

[Bubblehead]

Seems like a bad idea not keep a vent open on each tank. Could pressure/temperature changes cause damage?

 

[LoneStar]

Leaking Sensor

Every airplane I've ever flown or worked on has vented fuel tanks to include small general aviation aircraft up to transport catagory aircraft. They were all vented and checking the vents to ensure they were not plugged was part of the preflight. Fuel tanks are "sealed" to not leak, they nor there componets are designed to hold pressure. Once you have leak checked that tank it should remain so unless you damage the seal. Remember the majority of Boeings and Busses never or rarelly if ever fill there fuel tanks and there tanks don't leak, and they used the same fuel tank sealant you used. Good Luck.

 

[Pilottonny]

Hey guys, Euhhhhh, sorry but ......... I blocked the connections just to check the tanks for leaks! I do know these vents need to be open during normal operation! Everybody will have put a slight pressure on the tanks to check them for leaks, at one time. I just left the fuel in for a longer period, to make sure it was going to be OK, since a lot of people complain about wheeping rivets after they fill the tanks for the first time.

And no, the temperature in my shop is constant, no problem with building up a to high pressure from that. As a matter of fact, the pressure was not high, I could just hear the fumes escape when I opened the cap, just like with your car on a hot day.

In the meantime I understand from Rich Meske, that sealing the wires is not a good idea, because the electronics inside the sensor will always be immerged in the fuel. Although the sensor still works fine, I can understand that it is not the way it should be, so I am replacing it.

Regards, Tonny.

 

[Pilottonny]

Sensor split in two !

Today I took the cover off the tank and removed the sensor, guess what? Split in two! Maybe I overtighthened it, I don't know. It is good thing I checked, it, it was only the pro-seal holding it in place (and doing a good job at it).

I'l order a new one and will be more carefull thigthening it. One more lesson learned!

Regards, Tonny.