Fuel selector

Dave Oakes · #1 01-31-2005, 05:18 AM

I have not heard of anyone using the Cessna type selector. The fuel would feed from both fuel tanks at the same time.
Why is that?
I can see many advantages.
Thanks
Dave

N916K · #2 01-31-2005, 07:43 AM

I've always been told it's because RV's don't have a header tank so if one tank runs dry you could start sucking air. I haven't really looked into it but that sounds possible to me. Another reason is that it would be easy for fuel to flow from one tank to the other unchecked, resulting in a very heavy wing. High wing planes don't have this problem because of the whole gravity thing.

penguin · #3 01-31-2005, 12:02 PM

In a low wing aircraft with 2 wing tanks you should (must?) be able to select each tank in turn. As the previous post mentioned, if both are selected and one empties, the engine will suck air until you select only the tank with fuel in it. It doesn't matter how you uncover the fuel pick up in one tank (slipping, flying upside down, etc) the engine won't start drawing fuel again until both pick-ups are covered. IMHO poorly thought out fuel system modifications result in many engine stoppages. Why not stay with the simple, tried & tested system Van's recommend? Changing tanks every hour is not really a hardship. The only change I have made is an Andair fuel selector.

Pete

Dave Oakes · #4 01-31-2005, 12:51 PM

Having had only experience in a Cessna with the single fuel selector I did not know of the fact of the engine sucking air with one tank empty. It is no wonder that I had not heard of anyone using the "both" selectors. Thats the reason I ask.

Thanks for the information
Dave

Mustang · #5 02-04-2005, 05:25 PM

Dave,

Yes, if you do some research, you will find that no production low wing aircraft has a "both" selection on the fuel valve. For the reasons stated above. On the other hand, people that have attempted to re-invent the wheel and have installed a fuel selector with a "both" selection on their new RV, have had engine flameouts.

If you must modify your fuel system, the Andair valve is the way to go. Read about this and other fuel system problems in the latest issue, "21 YEARS of the RV-ATOR" distributed by the Builders Bookstore info@buildersbooks.com

Cheers, Pete