Switching Tanks Technique. How do you do it?

[Far North Texan]

We put a vapor return line on ours which returns some fuel to the left tank.

So when using the right tank, some fuel is going back to the left. With full tanks I always plan to start on the left.

To switch the fewest times, 45 minutes or an hour on the left, depending on my trip length of course. Then one hour, or even 1:15 on the right. Then back to the left for landing. I always switch at altitude over safe as possible terrain. I do not feel that it gets too badly out of balance. Fuel pump always on to switch.

Land on the fullest tank. I always take off on the same tank I last landed on unless I am doing an extended run up or taxi. I would never make a habit of changing tanks on the ground right before takeoff. Every time I even have the thought I slap my hand a couple of times. If it doesn't switch right for some reason then you get to find out at low altitude.

I do not have glass, or digital fuel flow, so I use a kitchen timer, pen, and paper

[Mel]

I've had fuel flow in my -6 since it was first built in 1993. Back then, virtually no one had fuel flow except the "big boys".

I have always switched tanks every 5 gallons. I start on the left tank after fill-up. My EI fuel flow reminds me when to switch.

In addition, I have the H-W Aviation ER tanks. When using them, I start out on left tank for 5 gallons, switch to right tank for 5 gallons, switch to left tank and turn on transfer pumps for 18 minutes (by D10A timer). This does not alter my 5 gallon per side rule.

[dlloyd3]

Since there are many variations in our fuel systems, what works for one may not be good for another. For any longer trips, you should have planned out what works in your airplane while on the ground. Then do that every long trip. Be consistent. Write down gallons used or time and update next switch. Doing the same thing over and over will help eliminate confusion as to where your fuel is and if there is enough.
Short trips, depart on the most full tank, arrive on the most full tank.
Switch tanks with the fuel pump on because that's what the instructions say

[uk_figs]

In the summer I tend to run autogas (no ethanol) in the left tank and 100LL in the right, I take off and land on the right tank to use the 100LL and cruise on the left. Landing on the right clears all the autogas out of the lines etc so no gumming up issues if the RV sits parked for a while. Use 100LL in the winter but generally fewer long distance flights.

I switch to the left when at cruise altitude and switch back to the right when entering the pattern at the destination airport (can make the runway if there is a problem).

Tanks do get somewhat unbalanced on a long X country but nothing that the trim or A/P cannot handle.

I chose the right tank for the 100LL as most patterns are left so no chance to unport the pickup even on low fuel.

Interested in what other people do who use a mix of mogas and 100LL do.

[Snowflake]

My procedure is to start and taxi on the lowest tank, and switch to fullest for run-up and takeoff. After that, switch every half hour.

[pvalovich]

I have a somewhat different procedure for switching tanks, especially on long cross country flights.

1. Generally try to minimize number of times I activate the fuel selector . Admittedly somewhat paranoid, but stuff wears out eventually.
2. Know - really know - how much fuel I have left. Err on having slightly more in the tanks than indicated. My red cube is calibrated tightly - 36 gallons pumped into the tanks usually shows 36.5 gal used on my AFS 4500. My float indicators aren't that accurate - but I know and understand those inaccuracies.
3. If I'm going to arrive at a destination with less than one hour of fuel remaining, I'll burn 20 gallons out of one of the tanks, then switch to the other. Don't want to worry about fuel management if I end up in an unplanned divert / holding situation.
4. For "normal" FACIT ("Fool" Around And Call It Training) flights I switch at 10 gallons used.

[RV7ator]

Couple of posters say they switch just before take off.

That's a very bad idea. Particularly if you've just added fuel.

I discovered two MINUTES at cruise power settings is required to consume fuel downstream of the valve in a -7 before fuel from a newly selected tank reaches the engine. At the trickle rate of consumption prior to take-off you may choose a tank with problem fuel that won't show up until you're a few feet off the ground.

Before start-up, select the tank you're going to use for the first 30 minutes of flight then don't mess with it until you're within a short distance of a suitable landing area. Thereafter, I keep a simple log on a scrap of paper showing the time and which tank when I switch on the quarter hours.

John Siebold

[F1R]

Originally Posted by RV7ator

Couple of posters say they switch just before take off.

That's a very bad idea. Particularly if you've just added fuel.

I discovered two MINUTES at cruise power settings is required to consume fuel downstream of the valve in a -7 before fuel from a newly selected tank reaches the engine. At the trickle rate of consumption prior to take-off you may choose a tank with problem fuel that won't show up until you're a few feet off the ground.

Before start-up, select the tank you're going to use for the first 30 minutes of flight then don't mess with it until you're within a short distance of a suitable landing area. Thereafter, I keep a simple log on a scrap of paper showing the time and which tank when I switch on the quarter hours.

John Siebold

It is also bad if the off position is selected by accident.

Some selector valves are quite easy to select off by accident. Especially if you fly multiple aircraft on the same day. Ask me how I know. Use a timer to see how long you can taxi around after the fuel valve is selected off. Just enough time for a run up and take off.

I personally do not touch any fuel valve before take off. Other than to make sure it is ON. I just make certain the tank selected has adequate fuel for the flight, with no water in the fuel.

[akarmy]

Originally Posted by uk_figs

In the summer I tend to run autogas (no ethanol) in the left tank and 100LL in the right, I take off and land on the right tank to use the 100LL and cruise on the left. Landing on the right clears all the autogas out of the lines etc so no gumming up issues if the RV sits parked for a while. Use 100LL in the winter but generally fewer long distance flights.

I switch to the left when at cruise altitude and switch back to the right when entering the pattern at the destination airport (can make the runway if there is a problem).

This is exactly what I do when on local flights. On XC I have the Skyview set at 8 gallons to notify me to switch tanks (5 was too frequent) and use 100LL in both tanks.

[BobTurner]

Originally Posted by uk_figs

I chose the right tank for the 100LL as most patterns are left so no chance to unport the pickup even on low fuel.

If you fly coordinated turns the fuel will not unport on right turns, either. However, you might consider slips - like in a crosswind landing - in choosing which tank to use.