No "BOTH" positions allowed on RV's

[Captain Avgas]

Originally Posted by vic syracuse

An "AUX" input port is different than a "BOTH" position on the selector. The BOTH position is an internal configuration that allows the tanks to feed simultaneously.

Vic

I just checked with the Andair site and you are correct. The "BOTH" selector is in fact an Andair FS20 Type 4. Porting for the "BOTH" position is done internally. In my plane I have an Andair FS20 Type 5 with the "MAIN" port capped and relabelled "AUX".

This has been an excellent thread. Very informative.

[pierre smith]

All Air Tractor models have an "On" and "Off" position....both tanks always feed. The fix is a header tank in the belly of the airplanes, which is where the fuel is fed from, whether one tank is empty or not and has been this way since the '70's.

The Cessna Agwagon series also had a belly header tank and they, to this day, run both tanks always. Neither airplane has 'left' or 'right' positions on the fuel selector.

We have too much else going on to worry about fuel management

Best,

[kbelue]

I certainly prefer a fuel tank selector that selects one tank or the other without a "Both" selection, but there are planes manufactured with a "Both" setting that work well. The Commander has a "Both" setting, but uses check valves to prevent one tank from feeding into the other tank. This requires that the check valves work and don't get stuck. I'd rather not have check valves because one may get stuck and not allow access to the fuel in that tank. The Air tractor tank design sounds like a good design. As always, the details are important....

Kevin Belue
RV-10
RV-6A

[jliltd]

The Aviat Husky has only "On" and "Off" selector for both wing tanks (or "both" and "off" as it were). It has the overhead vent interconnect line per the ease of high wing installation. It has no header tank. It is a Part 23 aircraft and Part 23 certification standards lean toward grandma-proofing everything on the aircraft. Not that grandma-proofing an aicraft is always a good thing.

Jim

[vic syracuse]

The bottom line is that IF the airplane is designed for a BOTH position on the selector it will probably work OK (Varga Kachina and some others are exceptions). But IF it wasn't designed for a BOTH, and it's already working well on approximately 10,000 flying airplanes, then we probably shouldn't mess with it. Just a thought.

However, I do wish we would standardize the way the fuel valve is installed in our RV's. Just today I performed a prebuy on an RV-8A that had the fuel valve installed such that the LONG arm of the selector points to the chosen tank. The little point on the small side of the selector handle had been ground off.




In my hangar currently undergoing a CI, I have an RV-10 that has the same valve installed such that the little pointer on the small end denotes the selected tank.




Perhaps we could all begin to paint the proper end with some bright red paint or something?

Vic

[JonJay]

As you know, but others may not, in "legacy" RV''s like my 6, the fuel valve is plumbed in a "cross over" configuration. In order for the fuel selector to be correct, the long side of the handle becomes the pointer. Hence, the pointer was ground off to avoid confusion. Painting it red would be a good idea.

[Sam Buchanan]

Originally Posted by vic syracuse

Perhaps we could all begin to paint the proper end with some bright red paint or something?

Vic

I agree. Guess my 1999 RV-6 is legacy but it is plumbed so the little pointer indicates the tank in use. The little pointer was painted red while the plane was still under construction.

I've done EAA inspections on RVs where I couldn't tell how the valve worked due to the lack of a clearly marked indicator. This became a point of discussion...maybe a dot of red paint will prevent a tragic accident by a future owner.

[Ironflight]

Ahhh...but does the red dot mean "danger, this end isn't the correct end!", or does the red dot mean "this is the important end!"

Mikey was built in the days when the handle was used as the indicator, and the little pointy end was ground off. I never liked that - just seemed backwards. We changed that valve handle during one of the upgrades, and it is much more intuitive.

[airtractor8]

Originally Posted by Sam Buchanan

The little pointer was painted red while the plane was still under construction.

I did the same thing. Here is a pic of the "Imperial" valve that came in my 1993 kit. It has a slightly different handle to the others shown in this thread and doesn't have the little pointer as such. Red pointed to the tank in use.
I removed it when it became so difficult to turn I was frightened the handle would break off halfway in between switching tanks It has a brass on brass type cone arrangement and despite several attempts to fix it nothing seemed to work. Could not stop the gland from seeping fuel either. Changed it out with an Andair. Problem solved

[vic syracuse]

Originally Posted by Ironflight

Ahhh...but does the red dot mean "danger, this end isn't the correct end!", or does the red dot mean "this is the important end!"

Mikey was built in the days when the handle was used as the indicator, and the little pointy end was ground off. I never liked that - just seemed backwards. We changed that valve handle during one of the upgrades, and it is much more intuitive.

One could paint the correct end of the valve a color (red) and paint the same color on the selector cover plate so they line up.

Vic