Tank switching

DrPappy

DrPappy

Pre-takeoff checklist
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DrPappy
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I was trained exclusively in high-winged aircraft (Cessna 150/152/172), where fuel tank selection was a part of the pre-flight (set to "both") and not routinely thought about afterwards. I was recently checked out in a Warrior (low-winged), and had this question: What do you do to remind yourself to switch tanks?

I have heard that some people like to switch after 30 minutes which certainly sounds reasonable. Is there a way you remind yourself? I use Foreflight on the iPad, so maybe some sort of reminder app? Or do you just wing-it, so to speak?
 
Does your watch or the panel mounted clock have a minute hand?

01-30, fly on the right tank
31-60, fly on the left tank.

Lemon Sqeezy.
 
Timer in the panel. Handheld timer also works. In a real pinch a smartphone stopwatch will do but I prefer a standalone timer.
 
DrPappy said:
I was trained exclusively in high-winged aircraft (Cessna 150/152/172), where fuel tank selection was a part of the pre-flight (set to "both") and not routinely thought about afterwards.
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You might want to check your aircraft documentation on the 172. Some of them require you to run on LEFT or RIGHT in cruise above a given altitude to avoid vapor lock.

Don't fly a warrior, but I use a timer. Fuel management in my plane is a bit more involved than the left-side/right-side watch half method would provide.
 
I write down the times I switch tanks with some special syntax that makes it easy to calculate total duration for each side. This way I make sure that I draw the equal amounts from them.

As far as reminding myself, I never felt a particular need. Flying VFR is usually so boring that anything to break it up is welcome.

Also, with my method, it's not important when to switch: a little earlier or a little later. I can easily even it out at the next cycle.
 
I do every thirty minutes, but I start with the left tank. I only mention which tank, because if you have strict habits, it helps you double check yourself on longer flights. For instance, if you took off at 10:00 and it is 11:40, you should be on the right tank.
 
I started out in the C152 and C172 world as well before moving on to Warriors and now an Arrow. In the Cessna it was Both from start to finish but the Piper line is a little different. i don't remember what the Warrior POH said off the top of my head but switching every 30 minutes seems about right. I used the digital timer on the dash or a check point on my flight plan that was close to 30 minutes as a signal to switch.

The arrow is different though. The POH and the checklist suggest taking off and climbing to your cruise altitude and then switching tanks. Fly on the second tank for 60 minutes and then switch every 30 minutes after that. This would help keep the weight of fuel in the wings somewhat even by accounting for the higher fuel burn during the climb.

As with everything, read the POH for your airplane and YMMV.

Also, you might download an egg timer for your iPad. I forget what one I started using but it would pop over ForeFlight and give a visual when the timer ran out. Download some free ones and see if they suit your needs.
 
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I used the timer on the 430/530. If I don't have one of those I just hack the clock on the panel.
 
Gucci Pilot said:
I used the timer on the 430/530. If I don't have one of those I just hack the clock on the panel.
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That's what I do too. Also, if you're familiar with the plane and the fuel gauges are accurate you ought to be able to predict when the Garmin alarm will pop up by how full the tank is.
 
If I'm flying a cross country and I'm using a paper nav log then I associate tank switching to waypoints and note it in the log. If I'm using my Nexus then I use the tank reminder feature in Avare. I'm often using both (I'm a belt & suspenders type of person) so the waypoint becomes the primary reminder and the timer is the backup.
 
pigpenracing said:
I know many people that just run till the engine quits, then switch.
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Brings up an interesting point. Someone in another forum brought up the topic of timing saying they wished more options, pointing out that some aircraft manuals call for such things as an hour on one tank, 2 hours on the other tank, etc, with some ultimately calling for running until empty on a tank before switching again.

I'll repeat what I wondered aloud there. Do many pilots still do that rather than do the half hour switching that seems to be so common?
 
Like Aggie Mike I use the minute hand method.

For your high wings.... you said set in on both during preflight and forget it....

I set it to LEFT for startup, switch to RIGHT for taxi, and then go to BOTH at the run-up pad before I do the mag check. This is to assure both tanks are feeding. Also because I know our Cardinal always drinks more from one wing I'll switch it the other one in flight for a while to 'balance her out'
 
midlifeflyer said:
If I don't have the GPS based timer, I run an app that anunciates my switch time.
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That's pretty OCD Mark. :D Afterall, when you suddenly find yerself in a glider you'll 'member to switch the tank! :hairraise:
 
rolivi said:
Like Aggie Mike I use the minute hand method.

For your high wings.... you said set in on both during preflight and forget it....

I set it to LEFT for startup, switch to RIGHT for taxi, and then go to BOTH at the run-up pad before I do the mag check. This is to assure both tanks are feeding. Also because I know our Cardinal always drinks more from one wing I'll switch it the other one in flight for a while to 'balance her out'
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Have you ever shut the fuel off to see how long it runs during taxi? Most of the airplanes I've tried it with have enough fuel in the lines to get me through taxi and runup with the fuel in OFF.

In other words, your technique might not be giving you the information that you think it is.
 
Funny you ask... I did accidentally switch a Cherokee to off instead of left it ran out about 500ft short of the run-up pad.

I'm going to find a nice IFR day to taxi around a lot and test out how long OFF lasts.

Thanks for the observation.
 
I switch when I'm over an airport is my only rule, otherwise I just check fuel levels and switch when one is significantly less than the other
 
rolivi said:
Funny you ask... I did accidentally switch a Cherokee to off instead of left it ran out about 500ft short of the run-up pad.

I'm going to find a nice IFR day to taxi around a lot and test out how long OFF lasts.

Thanks for the observation.
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Testing on a VFR day would be better, as long as the airport isn't really busy. That way if you have problems restarting, you won't hold up anyone's departure clearance. And you'll have an easier time pushing her out of the way if necessary.

I change tanks every hour. The clock in my yoke has a second set of [red] hands that I set at startup, and every time the minute hands overlap, I move the selector. Each tank is good for a little over 2½ hours; you guys with the thirsty Pipers may want to switch a little more often. :)
 
I used to have a 172 too and when people would ask me what my fuel management system was, I just said that when I am low on fuel, I fuel up. Now that I have a low wing with no "both" setting, I had to adapt.

I keep an eye on the fuel totalizer. I switch after 5 gallons is used, then when the amount of "fuel used" is a multiple of 10 more (ie, 15, 25, 35 etc) I switch. The totalizer is one of the items on my frequent scan list. On my note pad I have two columns, "Left" and"right". I note the amount used from each tank when I switch tanks. When I refuel, I am usually within about one or two tenths of gallon of what the totalizer said I would need.
 
teejayevans said:
I switch when I'm over an airport is my only rule, otherwise I just check fuel levels and switch when one is significantly less than the other
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I had to ferry a damaged cropduster back from Nassau to Opa Locka.

The previous ferry pilot had switched tanks over Nassau, causing the engine to fail - working theory was blocked injectors due to detritus in the jury-rigged hopper fuel installation. That issue came back to haunt me - twice - getting that cursed plane back to Opa Locka, causing a couple real "pucker moments".

In any case, he still came up short of the runway, damaging the gear in the process.

So, switching tanks over airports is a good idea and one I follow. But an equally good idea is to realistically practice engine-outs from over airports!
 
rolivi said:
Funny you ask... I did accidentally switch a Cherokee to off instead of left it ran out about 500ft short of the run-up pad.

I'm going to find a nice IFR day to taxi around a lot and test out how long OFF lasts.

Thanks for the observation.
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Maybe I just taxi and do my runups faster than most.

Whether that's good or bad...?:dunno:
 
JOhnH said:
I keep an eye on the fuel totalizer. I switch after 5 gallons is used, then when the amount of "fuel used" is a multiple of 10 more (ie, 15, 25, 35 etc) I switch. The totalizer is one of the items on my frequent scan list. On my note pad I have two columns, "Left" and"right". I note the amount used from each tank when I switch tanks. When I refuel, I am usually within about one or two tenths of gallon of what the totalizer said I would need.
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This is what I do. Obviously not everyone has a totalizer, but ours is quite accurate and a great tool. I switch approximately every five gallons and keep a log of exactly how much was burned from each tank with L and R columns on my kneeboard. If I'm behind and burn six from one side I'll try to get four the next cycle.
 
My 2003 Cirrus SR22 had a "Limitation" of no more than 10 gal imbalance side-to-side.

16624821373_e9a274a658.jpg


Speculation was that it was related to the autopilot's demonstrated ability to deal with the imbalance, but otherwise not a big deal.

Most in the Cirrus world back then would program their 430's to message "SWITCH TANKS" every 20 or 30 minutes. As I said, when I got the message I would, out of habit, wait until within gliding range of an airport to switch.
 
I switch tanks every 10 gallons in the Arrow. In the Maule I'll only switch off of both when the fuel gets about 1/4-1/2 of a tank difference.

The Maule really depends on which tail number I'm flying. The tanks are hand made and installed in a mostly hand made wing. This leads to each plane having a different personality in fuel burns.
 
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FastEddieB said:
My 2003 Cirrus SR22 had a "Limitation" of no more than 10 gal imbalance side-to-side.

16624821373_e9a274a658.jpg


Speculation was that it was related to the autopilot's demonstrated ability to deal with the imbalance, but otherwise not a big deal.

Most in the Cirrus world back then would program their 430's to message "SWITCH TANKS" every 20 or 30 minutes. As I said, when I got the message I would, out of habit, wait until within gliding range of an airport to switch.
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You can get pretty interesting imbalances on a number of different aircraft. In the early hours of flying it, I once forgot to switch tanks in a Bonanza for only about an hour and was reminded (and also reminded the airplane had aileron trim) because the airplane kept "pulling to the left."

I treat my 30-minute reminder not as "switch tanks NOW!" but as a reminder to "consider" switching. Location is one factor but there may be others. So, for example, after an extended climb at a higher power setting, the response the next time prompted to switch to the "climb" tank might be, "nah, I'll wait for the next one."

That's what I like about the 30 minute prompt. Often enough to take care of a fuel mismanagement problem; spread apart enough to not be annoying.
 
I use to do the swap every 30 minutes until I put a EI CGR-30P engine monitor in my plane. Now it annunciates to swap tanks every 5 gallons of fuel burn.
 
I start on the fullest tank and go every thirty minutes, unless my leg is under an hour, in which case I'll just switch tanks on the ground at the halfway point.
 
I have a fuel totalizer that is extremely accurate (within 0.1 to 0.2 gallons). I switch tanks based on gallons rather than time. First switch is faster due to the climb. Normally switch at 8 gallons intervals, but adjust for endurance and have it written on a knee pad for LT and RT total used per side and remaining per side, then total overall. Works out great because by the time I boost pump ON, switch, and write that stuff down, it is then time for boost pump OFF.
 
I use a slightly different approach. When flying a longer X/C, I plan the fuel tank switch on the flight plan. Whenever I am over a suitable airport, I switch the tanks. It usually works out to 30-45 minute legs.
And since it is part of the flight plan, I don't need a timer or reminder, it is right there on the paper. :)
 
BigBadLou said:
I use a slightly different approach. When flying a longer X/C, I plan the fuel tank switch on the flight plan. Whenever I am over a suitable airport, I switch the tanks. It usually works out to 30-45 minute legs.
And since it is part of the flight plan, I don't need a timer or reminder, it is right there on the paper. :)
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PAPER??? What's that?;)

Oh yeah, good plan.
 
How did anyone ever fly without fuel flow sensors and totalizers? On the other hand, some here appear to spend more time obsessing about fuel imbalance than with preflight planning.

My Owners Manual recommends switching one hour after departure then running the second tank dry before switching back. I'm more conservative than that, so I switch every hour and don't sweat a few minutes' difference unless I'm going to be near my endurance limit, and even then I'll plan a fuel stop.

It's really not that hard. Although too many pilots run out of fuel completely, which goes back to PLANNING.
 
I don't think I obsess about it, but I do spend more time on it than I would have imagined. I just sold a high wing so this fuel management business is new to me.
For one thing, one of the (few) things I am disappointed in with my Bonanza is that if there is less than about 23 gallons in the tank, it doesn't touch the measuring stick. That is more than half of either of the 40 gallon tanks, so I can have almost 50 gallons and it would look empty. If I don't pay close attention I could wind up with a lot of fuel in one tank while running the other empty. Not good during a short final.

Hank S said:
How did anyone ever fly without fuel flow sensors and totalizers? On the other hand, some here appear to spend more time obsessing about fuel imbalance than with preflight planning.

My Owners Manual recommends switching one hour after departure then running the second tank dry before switching back. I'm more conservative than that, so I switch every hour and don't sweat a few minutes' difference unless I'm going to be near my endurance limit, and even then I'll plan a fuel stop.

It's really not that hard. Although too many pilots run out of fuel completely, which goes back to PLANNING.
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I'm running mogas in my plane and my mechanic suggested I fill one tank with avgas and switch to it when entering the pattern on the way in. That way all the seals will have avgas around them when the sits idle. He said mogas makes seals shrink and avgas makes seals expand.
Otherwise I use both tanks in my Cardinal.
 
midlifeflyer said:
Brings up an interesting point. Someone in another forum brought up the topic of timing saying they wished more options, pointing out that some aircraft manuals call for such things as an hour on one tank, 2 hours on the other tank, etc, with some ultimately calling for running until empty on a tank before switching again.

I'll repeat what I wondered aloud there. Do many pilots still do that rather than do the half hour switching that seems to be so common?
Click to expand...

My opinion is that you shouldn't run one tank try and switch to the other, because if the fuel selector fails, you've got an empty tank. Or, if there is an issue with feeding from the tank you just switched to, you can switch back to the other one and it will still have fuel in it.

On the Archer I switch every 30 minutes. The Evektor I switch every hour as it only burns 4 GPH or so.
 
Hank S said:
How did anyone ever fly without fuel flow sensors and totalizers? On the other hand, some here appear to spend more time obsessing about fuel imbalance than with preflight planning.

My Owners Manual recommends switching one hour after departure then running the second tank dry before switching back. I'm more conservative than that, so I switch every hour and don't sweat a few minutes' difference unless I'm going to be near my endurance limit, and even then I'll plan a fuel stop.

It's really not that hard. Although too many pilots run out of fuel completely, which goes back to PLANNING.
Click to expand...


I wonder about the prudence of the Owner's Manual switching from an intentionally dry tank, likely done to maximize the range. Should the other line will not deliver, then you are suddenly in an overweight glider. Not having the option to switch back would suddenly transform the "oh crap" moment to an "oh sh**" moment. :hairraise:
 
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