Switching Tanks Technique. How do you do it?

Vlad · #1 10-04-2015, 05:32 PM

It looks like a very simple operation to switch fuel tanks in flight. But since Paul Dye landed his RV-3 on a road I am always thinking twice before touching that selector knob. Especially when I am flying over inhospitable terrain or on top of a layer. Would be interesting to learn how others are performing this simple operation. RVs or not, VFR or IMC, please share your technique. What's your methodology long haulers? How would you manage your fuel for 5+ hours non stop?

N941WR · #2 10-04-2015, 05:46 PM

First off, I have an Andair valve, so I have very little to no worries about my valve sticking.

To answer your question, I switch them every half hour by first turning on the electric fuel pump, switching tanks, and turning the pump off.

Auburntsts · #3 10-04-2015, 05:51 PM

I switch every 30 min without the boost pump regardless of whether I'm VFR or IFR using the tank alarm function on my EFIS. I have a fuel data log I print up for my kneeborad that fill out enroute so immediately after I switch tanks I dial my fuel totalizer page on my MFD and copy down the consumption figures and manually do the math on the total remaining. I have absolute faith in my red cube which has been dead on accurate to the tenth of a gallon.

Greg Arehart · #4 10-04-2015, 06:18 PM

I just switch them (approximately) every half hour based on the timer on my Dynon. I also have the Andair valve. I then monitor the tank float gauges to make sure fuel is actually coming out of the other tank (so far has worked every time

). I try to do the swap over some sort of reasonable landing area if possible, but don't really worry about it too much. I don't bother turning on the second fuel pump.

Greg

rolivi · #5 10-04-2015, 06:24 PM

I use the minute hand of my watch. From 00-29 minutes I'm on the right tank and from 30-59 I'm on the left.

When I get distracted it's easy to look at the watch and confirm I'm on the correct tank. Much easier than writing it down and logging the changes.

Steve Melton · #6 10-04-2015, 06:32 PM

I switch tanks each hour and always land with at least one hour of fuel in the tanks.

erikpmort · #7 10-04-2015, 06:38 PM

I don't switch my tanks that regularly and don't see a big problem with med size fuel differences in my tanks. I never switch tanks unless I'm somewhere I'm ok with loosing a motor. It's a risk. Everytime.

Toobuilder · #8 10-04-2015, 06:40 PM

30 minutes at the first switch; every hour after that. If I'm looking to land at VFR minimums I'll run one tank dry, then land with all remaining fuel in one tank.

I try to make sure the switch happens near an airport or at least a safe place to land. Because I generally expect the handle to come off in my hand every time, I'll really avoid making ANY configuration changes over hostile territory.

rvbuilder2002 · #9 10-04-2015, 06:51 PM

I believe that switch tanks as few times as necessary reduces risk....

So I fly the first 30 minutes (including takeoff and climb) on one tank (doesn't matter which).
After switching to the second tank, I use it for one hour (the first 30 minutes on the second tank brings them back to being approx even in fuel level... the second 30 minutes makes the second tank go lower by 30 minutes).

I then make each tank switch at 1 hr intervals after that....
The fuel imbalance is then never more than 4-5 gallons (30 minutes of fuel burn), and a typical cross country leg will usually only require three switches at the most... sometimes only two.

I make exceptions to this based on the availability of suitable forced landing sites... I only switch if a have a decent forced landing site available (preferably a runway, paved road, dry lake bed, etc.)
Not following an exact time pattern doesn't matter to me because I keep notes of how many minutes I burn on each tank.

BTW I think there is some level of inherent risk regardless of what brand fuel valve you have..... anything can break.... and it will always happen at the most inopportune time.

Pat Stewart · #10 10-04-2015, 06:59 PM

Quote:

Originally Posted by rvbuilder2002

I believe that switch tanks as few times as necessary reduces risk....

So I fly the first 30 minutes (including takeoff and climb) on one tank (doesn't matter which).
After switching to the second tank, I use it for one hour (the first 30 minutes on the second tank brings them back to being approx even in fuel level... the second 30 minutes makes the second tank go lower by 30 minutes).

I then make each tank switch at 1 hr intervals after that....
The fuel imbalance is then never more than 4-5 gallons (30 minutes of fuel burn), and a typical cross country leg will usually only require three switches at the most... sometimes only two.

I make exceptions to this based on the availability of suitable forced landing sites... I only switch if a have a decent forced landing site available (preferably a runway, paved road, dry lake bed, etc.)
Not following an exact time pattern doesn't matter to me because I keep notes of how many minutes I burn on each tank.

BTW I think there is some level of inherent risk regardless of what brand fuel valve you have..... anything can break.... and it will always happen at the most inopportune time.

When flying an RV other than the 12 I use this same procedure.