Thanks to all who responded to my post. Now I've got a better understanding of how fuel-siphoning can affect the operation of the fuel system generally.
I've contacted John Wright, Jr., and will be sending my tank to him for repair. Keep Coupes flying! Bill T. --- In [email protected], Hartmut Beil <hb...@...> wrote: > > > Bill:" Is it because the suction affecting the right tank, through the > cracked flange, is more than the fuel pump's suction can overcome?" > > > > Hartmut: I think the suction of the pump was good enough as long as there was > something to suck. > > When your left tank showed empty, the tank and the tanks interconnecting fuel > lines where empty. The only remaining fuel was slowly pulled over into the > right tank and held there due to the suction. Now not much was left for the > pump to get. It received maybe a mix of air and fuel, thus showing only a > slow sinking float. > > > > However. Question now is ho are you going to repair this crack? > > > > In our wing tanks the fittings are riveted from inside as is the filler neck. > One needs to disassemble the whole tank to replace that neck. Maybe you can > get away with stop drilling the crack and then sealing it with pro-seal... > > > > Hartmut > > > > To: [email protected] > From: w...@... > Date: Mon, 14 Sep 2009 19:12:41 +0000 > Subject: [ercoupe-tech] Fuel Siphoning Issue > > > > > > First, the particulars about my plane: > 415-C, S/N 4313 > 9 gallon aluminum wing tanks, vented caps > Skyport Rain-pruf nose tank guage, vented > fuel pump is less than one year old, and has about 15 hours on it. > > Bear with me for the background. > > Went flying yesterday and my passenger noticed fuel siphoning around the cap > on the right wing tank, about 15 minutes after takeoff. (The wing tanks were > about 3/4 full, and the fuel level was the same on each side before takeoff.) > > I did a 180 to return to the airport and, as we were on our way there, I > noticed that the gauge in the left wing tank had dropped to "0". Then, a few > minutes later, the nose tank float gauge (a Skyport Rain-pruf version) > started dropping: not drastically, but definitely noticeable. Shortly before > we got back to the airport, the siphoning had stopped, but the left tank > gauge still read "0". After we landed and were taxiing in, the nose tank > float gauge gradually returned to the "Full" mark on the glass tube. > > We parked on the ramp and started investigating the problem. We noticed that > the fuel levels in the wing tanks had stabilized and were again equal (but > down to about 1/2 full after the flight and the fuel siphoning). > > I thought I had a cap-sealing problem on the right tank. Not so: the problem > was the tank filler neck flange, which was cracked about a third of the way > around its circumference. The fuel was siphoning in the small area between > the outer edge of the cap gasket and the upper skin of the tanks. In flight, > it looks like it's coming out from under the gasket. The crack isn't visible > from the top: you need a mirror in the fuel filler hole, and a flashlight. > > OK, so that's the story. But I'm puzzled. I understand that the fuel will > siphon because there is a pressure differential between the tanks, as a > result of the crack. Low-pressure area and all that. But what I don't > understand is, Why would the nose tank level drop? After all, there was still > plenty of fuel in the right tank ("pulled" over there from the left tank by > the pressure differential.) Is it because the suction affecting the right > tank, through the cracked flange, is more than the fuel pump's suction can > overcome? > > Thanks for listening! > > Bill T. > > > > > > > > > > _________________________________________________________________ > Share your memories online with anyone you want. > http://www.microsoft.com/middleeast/windows/windowslive/products/photos-share.aspx?tab=1 >
