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View Full Version : Sump for auxilary tank



smcnutt
08-10-2010, 02:22 PM
Our plane has an auxiliary tank installed under the rear seat. We've never actually used it but we did rebuild the pump and valve to make sure everything was in working order. However, I noticed that the tank does not have a sump drain on it and I'm not sure if it was supposed to. Sounds a little scary to pump 8 gal from it into your right tank and not be able to check ahead of time if you've got good fuel or not.

Should this tank have a sump and if so, where is it placed? Any pictures would be great.

Steve Pierce
08-10-2010, 04:42 PM
There is a place on the right rear where there is normally a plug. The problem with a sump on this tank is that there is a block of aluminum welded into the tank and the recess is not deep enough to allow the sump drain to actuate very far. I have a Safe-Air in mine and can barely get anything out of it. I thought there was something wrong with the tank until I looked at one I have on the shelf.

Steve Pierce
08-10-2010, 04:50 PM
I took some pictures, don't pay any attention to the scuff mark. :frown:

smcnutt
08-11-2010, 11:25 AM
Doesn't that place the sump on the high side of the tank in a tail dragger?

Steve Pierce
08-11-2010, 11:47 AM
You are correct.

smcnutt
08-11-2010, 12:13 PM
Maybe that's why the sump wasn't installed in my plane. Not sure I like the idea of pumping 8 gal of unknown contents up into the main tank. Like I said, we've never used the tank and quite frankly, don't think we would need it. I mean adding an extra hour flight time is way more than my butt or bladder could handle over the regular tanks.

However, since we've never used it, who knows what garbage would be in that tank. Maybe we will wait till the right tank is almost empty and fill and xfer fuel from the Aux tank (while on the ground) and see what it produces. I guess if you were to use it a lot then you would have less crap build up in the tank and would have less concerns of pumping the contents into your main.

jbert
08-12-2010, 12:42 AM
I used the aux tank for several years in my taildragger with the same concerns as expressed above. The tank was cleaned thoroughly when installed. In use to mitigate build up of moisture or crud I would fill both wing tanks and check for water/crud then fill the aux tank. The tank was filled and drained twice on trips between Colorado Springs and CA. I would leave it full to minimize moisture buildup due to diurnal temperature variation that is usually no real issue in CO anyway. I never experienced any problems with fuel from the aux tank.

During a recent cockpit rebuild I had a boss welded on the bottom near the right rear corner of the tank and installed a fuel drain. Works fine.

Steve Pierce
08-12-2010, 07:03 AM
The fuel pump has a screen in it and the fuel will have to go through the gascolator under the right seat and the main gascolator before making it to the carburetor. Probably a good idea to weld a bung in the rear of the tank on tail draggers.