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Leaky fuel vent
Posted: Tue Sep 14, 2004 2:44 pm
by dkalwishky
I've noticed that when I park my plane and it's not level the fuel tank vent will drip fuel. The obvious fix is to park the plane level, but thats not always possible.
Does anyone have any suggestiones to help fix this problem? One thing that comes to mind is fabricate something to plug the hole while on the ground and mount a red flag to it so it doesn't get forgotten.
I wonder what effect turning the fuel selector to OFF would have on this.
Dave
Posted: Tue Sep 14, 2004 2:53 pm
by n3833v
When I park and know that I will overrun one tank, I turn the selector to the low tank to isolate from the other tank.
Posted: Tue Sep 14, 2004 3:02 pm
by GAHorn
Dave, what model airplane do you have? A 172? The 170 vent is on top of the cabin and will not normally drip such as you've described.
Plugging your vent will likely pressurize your fuel system and may cause harm (especially if you have rubber bladders such as in a 182/206/etc.)
The easiest solution is probably not to fill your tanks quite so full. Switching the fuel selector OFF will not have any effect. (Except to embarrass you when you taxi away from the chocks in full view of everyone and the engine dies.)

Posted: Wed Sep 15, 2004 2:25 am
by dkalwishky
I have a '56 C172.
Dave
Posted: Wed Sep 15, 2004 7:49 am
by ak2711c
Turnning the selector off to stop the tanks from cross feeding and overflowing the low wing tank is common practice while parking on a sloped beach or any surface that leaves the plane sitting at a pretty good angle. Sometimes the fuel will overflow out the vent or sometimes the cap if you don't.
Shawn
Posted: Wed Sep 15, 2004 7:55 pm
by GAHorn
(My comment regarding turning the fuel selector OFf having no effect was only in reference to a 170 with the over-cabin fuel vent.)
Fuel selector setting
Posted: Thu Sep 16, 2004 5:36 am
by n1410d
Just a quick note. Turning the fuel selector to the off positon will NOT prevent fuel from transferring from the high tank to the low tank when parked on a slope. If you look at the construction of the shaft on the fuel selector valve you will see three holes drilled at 90 degree angles, with the fourth side solid. When the selector is on both the holes line up with the left and right tank fuel lines and the outlet to the gascolator. If you turn the valve to off the hole lining up with the outlet to the gascolator is turned 180 degrees and the side with no hole drilled in it is positioned facing the outlet to the Gascolator. BUT the two holes on either side are STILL lined up with the fuel lines from the left and right tanks. Fuel will seek the lowest tank in the off position. Turning the selector to the lower tank is the procedure to preventing uneven fuel loading.
By the way when was the last time you switched tanks or shut the engine off using the fuel selector valve???? Might be a good idea to make sure it is working properly.
I test flew a friends Cessna 140 that just came out of the shop for some radio work. The 140 does not have a both setting, just a left, right, off. Well about 45 minutes into the flight I decieded to switch tanks and was rewarded with silence about 5 seconds later. Of course I switched back to the tank I was using and got the sweet sound of combustion back. Well upon further trouble shooting I noticed that although the selector was on the left tank. the right tank reading lower than the left. YOU GUESSED IT!!!!!!!!!!! THE AVIONICS TECH SICK OF HAVE THE FUEL SELECTOR HANDLE STICKING HIM IN PLACES HE DIDN'T ENJOY REMOVED THE HANDLE. Upon replacing it he put it on 90 degrees out.

So Left was right and right was off. Just one more example of why you need to really really check your plane after you get it back from a shop. Just because they are working on an encoding altimeter doesn't mean they aren't going to screw up your fuel selector valve.
Pat n1410d Grand Prairie TX
across from Joe, Not too far from Chuck.
Posted: Sat Sep 18, 2004 3:33 am
by dkalwishky
Thanks for the posts guys!
I rotate my fuel selector between tanks on EVERY flight. I saw a post a long time ago from George on why to do this and I've done it ever since.
Dave