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Permalink Reply by Gary Welch on December 12, 2021 at 10:53am

No, it's not normal and it's not safe, IMO. First off you have no way to manage fuel flow in each tank. The argument that "since their connected together fuel will flow equally from each tank" is not true. There are a million posts on the internet about this subject in just about every type of aircraft. For all kinds of reasons, fuel will flow differently from the tanks. 

The whole concept of fuel redundancy is gone.

When one tank or the other reaches empty you can suck air from that tank that can result in an engine stoppage. You have no ability to isolate one tank should you have any kind of problem. There is a reason while almost every low wing aircraft, and most high wing aircraft have selectable right and left tanks. Even high wings that do have a "both" option, they also have a left or right selection as well.  

This is a case of the builder thinking he is smarter that what 100 years of aircraft building has taught us, and been paid for in blood.

Personally, I would be concerned what other decisions the builder made because he that he thought he was smarter than the rest of aviation. Don't mean to be alarmist, but I think it's a valid concern. I would try and get a professional review of the aircraft by either an experienced 601/650 builder, or an A&P. Preferably an A&P. 

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Permalink Reply by christopher fryatt on December 12, 2021 at 4:56pm

cessna  150   fuel selector on , or off.

but has venting overboard plus inter tank vent line 

Most all low wing aircraft have left or right since no interconnect vents. i have 4 tanks piped into a four port selector. , running one at a time allows for wing balancing via fuel

601xl

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Permalink Reply by Bob Pustell on December 12, 2021 at 9:40pm

Don't let the Cessna "both tank" settings make you feel good. It takes a lot of engineering work to let a Both setting work safely.. And even then almost all Cessnas (except that 150 the guy mentioned) have a left tank and right tank postiion in addition to the both position. My 73 year old Stinson 108 high wing plane has a left, right, off fuel selector. No both postion. 

Unless the person who built up your project has a lot of expertise I am in agreement with Gary - this person thinks they know a lot more than a century of avaiton has taught people. We do things the way we do them because people have died doing them differently. Don't go with this person's design unless you see a LOT of supporting reserarch and design data. Re-plumb it to allow feeding from only one tank at a time or else do a lot of engineering work to assure safe operation with multiple tanks feeding at the same time.

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Permalink Reply by Glenn Davis on December 12, 2021 at 10:48pm

I use the Viking mini header fuel system on my 650. Both tanks gravity feed to the vented header at the same time with no problem. I do have in line valves to isolate a tank if necessary.

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Permalink Reply by Guy Magnuson on January 28, 2023 at 2:23pm

How did you accomplish gravity feed to your header tank with a 650?

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Permalink Reply by Stephen M. Eastham on June 29, 2023 at 3:42pm

The "header' tank is on the floor in the center console lower than the tanks.

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Permalink Reply by Douglas Binder on December 13, 2021 at 7:42am

The Cessna 150 I fly does not have a selector valve and can get alarming when one tank shows almost empty and the other half full.  I fly in a slip for a while to try to balance them.

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Permalink Reply by David Walsh on December 14, 2021 at 12:08am

Thanks for all your comments on this one. Yes I will be fitting a four way selector to ensure fuel feed is controlled. I am surprised the kit instructions did not call for or supply this which was why I asked the question. Thanks again. 

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