Switch Tanks Before Takeoff

[Hank]

Me too, @Utah20Gflyer. Except I switch at an hour, every time the moving white minite hand overlaps the resetable but non-moving red hands on my yoke clock.

[Shadrach]

4 hours ago, PT20J said:

The only failure I personally know about was a friend in an Archer that had the screw attaching the handle back out and jam the handle in the trim around the selector in a position between tanks where I have one of those models with a recessed fuel selector under the pilots left legno fuel flowed. In a slight panic, he tried to force it and jammed it worse. He finally got it unstuck. 

I have one of “those models” with a recessed fuel selector under the pilot’s right leg. I had the exact same issue after replacing the carpets many years ago. One of the trim screws was not properly tightened and it prevented the selector from rotating much beyond the off position. The interior replacement was a group effort so I didn’t even know who to blame. Fortunately I caught it during the very thorough post-maintenance preflight so it was a non-issue. Incidentally, I’ve Never found it a challenge to reach and manipulate the fuel selector… as it turns out there are some benefits to being a knuckle dragger.

[Utah20Gflyer]

53 minutes ago, Shadrach said:

I have one of “those models” with a recessed fuel selector under the pilot’s right leg. I had the exact same issue after replacing the carpets many years ago. One of the trim screws was not properly tightened and it prevented the selector from rotating much beyond the off position. The interior replacement was a group effort so I didn’t even know who to blame. Fortunately I caught it during the very thorough post-maintenance preflight so it was a non-issue. Incidentally, I’ve Never found it a challenge to reach and manipulate the fuel selector… as it turns out there are some benefits to being a knuckle dragger.

I had an incident where a screw from an interior trim panel came out and ended up in the recessed fuel selector assembly.  when I tried to switch tanks the screw jammed the fuel selector lever at about the off position.  I turned it back to the previous tank and fished the screw out and then successfully made the tank switch.  
 

High pucker factor for about 15 seconds until I figured out what had happened.  

[EricJ]

I'm probably one of the few people that does the L-R gascolator drain before start, i.e., turn it one way, pull the ring for a second or two, turn it the other way, pull the ring for a second or two.    At that point I decide which tank I want to start on, which will also be the tank that I taxi, runup, and takeoff on.

Doing the L-R switch for the gascolator pull verifies that the handle can be turned through the entire range, and also drains any water out of the gascolator and the low parts of the lines feeding the gasolator.

The bad part of this is that many airports typically don't want you to do this, i.e., drip gas on the pavement.    On many Mooneys it's difficult to avoid it without a second person outside the airplane catching the fuel.   I don't like to splatter the fuel around, but I more don't like not being able to hit those items on the check list.

When I was buying my airplane and Rich @N201MKTurbo was getting ready to fly it to TX so Maxwells could fix the tank leak and do the prebuy, he pulled the ring while I held a jar underneath to drain a pretty fair amount of yellow-ish water out of the gascolator.   It had been flown to my hangar with a bunch of water in it, and we drained a bunch more before he flew it to TX.   I drained water out of that airplane for weeks after I picked it back up from TX, I think some of which was recharged by it getting left out in a heavy rain shower.    I've not seen water in it for many years, but I still drain the gascolator.   

[N201MKTurbo]

I have a stopwatch clock in the plane that I use as a flight timer. I always start on the right tank. That way if the minute hand of the stopwatch is on the right side of the clock, I’m on the right tank, when it is on the left side of the clock I switch to the left tank.

If the left tank if fuller, I start on the left tank and run it for an hour until the clock is synched with the fuel selector again.

[GeeBee]

10 hours ago, EricJ said:

I'm probably one of the few people that does the L-R gascolator drain before start, i.e., turn it one way, pull the ring for a second or two, turn it the other way, pull the ring for a second or two. 

Don't know about your POH, but mine requires that as well and for 5 seconds on each tank.

[Pinecone]

19 hours ago, Nokomis449 said:

during the preflight I found the fuel cap incorrectly installed (it was at an angle instead of flat) and got nothing but water from the sump.  After the 3rd cup, I asked for the FBO manager, who himself found the other tank in the same condition.  If memory serves, the lineman then sumped about a gallon from each wing.  When even slightly askew, the O-ring does not completely seal and water that collects on top of the fuel cap meanders into the tank.  So at the risk of being labeled "THAT pilot", I point out an incorrect cap position any time I find it, and why.

I am thinking about getting these to carry in case the plane has to sit out with a chance of rain.  But with Monroys, I need 2 sets. 

 

Fuel Cap Covers - Set Of 2 | Aircraft Spruce

 

[Pinecone]

11 hours ago, EricJ said:

The bad part of this is that many airports typically don't want you to do this, i.e., drip gas on the pavement.    On many Mooneys it's difficult to avoid it without a second person outside the airplane catching the fuel.   I don't like to splatter the fuel around, but I more don't like not being able to hit those items on the check list.

Somewhere on MS there is a 3D design for a holder that uses a spring clamp to hold onto the nose gear door and holds a GATS jar to catch the fuel. 

My friend had to modify the design a bit as it was a bit too small for a recent GATS jar.

[Pinecone]

18 hours ago, Utah20Gflyer said:

I started my plane with the fuel selector on off and ran it until it died, maybe a minute at idle power.  So from my experience any quick switch from one tank to another doesn’t prove anything.  A full run up would prove it, but I don’t want to do two full run ups .

Following my POH, I start and taxi on one tank.  They switch, do the run up, and then maybe wait for traffic, and taxi onto the runway.

So each phase it more than long enough to indicate fuel selector/tank issues.

[MikeOH]

5 hours ago, Pinecone said:

I am thinking about getting these to carry in case the plane has to sit out with a chance of rain.  But with Monroys, I need 2 sets. 

 

Fuel Cap Covers - Set Of 2 | Aircraft Spruce

 

I've been thinking about making my own...70 bucks is a little steep for my CB taste

[jlunseth]

I follow my checklist. (I wrote it.) My checklist says to switch to the fullest tank for start up and the part of the checklist that I do on the ramp, then switch to the other tank for taxi and run-up, then switch back to the fullest tank for takeoff. Now, in addition to having sumped the tanks, I have verified that there is good fuel in both tanks. That way not only do I insure I have good fuel for takeoff, but I have also insured that I don’t get down range somewhere and over the middle of nowhere, and then change to an untested tank. I used the basic format for checklists that the school where I got my PPL uses for its Pipers, Warriors, Archers and Arrows and modified it for my 231.

Edited December 9, 2023 by jlunseth
I hate autocorrect.

[Fly Boomer]

19 hours ago, EricJ said:

I'm probably one of the few people that does the L-R gascolator drain before start, i.e., turn it one way, pull the ring for a second or two, turn it the other way, pull the ring for a second or two.    At that point I decide which tank I want to start on, which will also be the tank that I taxi, runup, and takeoff on.

Doing the L-R switch for the gascolator pull verifies that the handle can be turned through the entire range, and also drains any water out of the gascolator and the low parts of the lines feeding the gasolator.

The bad part of this is that many airports typically don't want you to do this, i.e., drip gas on the pavement.    On many Mooneys it's difficult to avoid it without a second person outside the airplane catching the fuel.   I don't like to splatter the fuel around, but I more don't like not being able to hit those items on the check list.

When I was buying my airplane and Rich @N201MKTurbo was getting ready to fly it to TX so Maxwells could fix the tank leak and do the prebuy, he pulled the ring while I held a jar underneath to drain a pretty fair amount of yellow-ish water out of the gascolator.   It had been flown to my hangar with a bunch of water in it, and we drained a bunch more before he flew it to TX.   I drained water out of that airplane for weeks after I picked it back up from TX, I think some of which was recharged by it getting left out in a heavy rain shower.    I've not seen water in it for many years, but I still drain the gascolator.   

That will certainly answer the question "will the selector move freely from one tank to the other".  I still want to verify that the engine will produce power on either left or right.

[ZuluZulu]

On 12/8/2023 at 8:48 AM, PT20J said:

I switch tanks every half hour. I like to keep the plane balanced and also those brass valves like to be exercised or they get stiff. 

I usually taxi out on one tank and switch before run up. This is primarily to make sure the valve turns freely - I’m really not much concerned that somehow fuel won’t flow through the lines. And, I sumped the tanks, so I know there is no water (BTW, in 6,000 hours of flying a lot of different make and model airplanes, I have found a significant amount of water in the fuel tanks exactly ONCE. But, I still sump the tanks. You never know when twice will occur.)

If you want to avoid the biggest risk, check the handle attachment. The only failure I personally know about was a friend in an Archer that had the screw attaching the handle back out and jam the handle in the trim around the selector in a position between tanks where no fuel flowed. In a slight panic, he tried to force it and jammed it worse. He finally got it unstuck. I could easily see the handle on my J coming loose and getting dropped and rolling under the seat. And then there are models with the valves that you cannot hardly reach without gorilla arms or an extension…

Skip

 

I also switched every hour. I had a timer set up on the GTN that would send me a “switch tanks” message every 30 minutes. Worked like a charm. 

[Jeff Uphoff]

On 12/7/2023 at 8:03 PM, Fly Boomer said:

Having breakfast with pilots this morning, we discussed (among many other topics) tank switching before takeoff.  It seems to me that a good idea might be starting and warming up on one tank, and then switching tanks before runup and takeoff.  My argument is that if there is a fuel delivery or contamination problem, I want to know about it while still on the ground.  Some said they always want to take off on the same tank they were on at start.  In other words, they were concerned that the runup might not burn enough fuel to assure that the "new" tank didn't have a problem. 

What do Mooney drivers do?

I start on my not-as-full tank, which is usually the one I landed on the previous flight, then I switch tanks after about 5 minutes of pre-taxi idle--after I have my avionics set up, autopilot (self-)tested, listened to the ATIS, etc. That way I taxi out and run up on the tank that's fuller--the one I want to use for takeoff.

In cruise, I try to always switch tanks within gliding distance of a decent-sized field--one I could be confident dead-sticking into.

--Up.

[Schllc]

Seems like there are good and valid reasons for a variety of methods. 
I am a big fan of routine/consistency.  Not simply for thoroughness, but you can discern and discriminate other issues quicker when you have confidence in your routine. 
I wouldn’t want to have some obvious engine problem like fouling of plugs or mags to make me wonder if it was because I switched tanks and got hyper focused on that deviation from the routine. 
I get as close as I can upon landing to even my tanks. If I add, I add evenly, or top off, always. 
I land on that tank and switch at shutdown, don’t touch again until first tank switch. 
I do the same thing with my batteries. 
If something has been working for years, and unless there is very good reason to change, stick with what works and what you do consistently. 
It’s all about mitigating risk, and external evidence is as important as understanding our weaknesses and supplementing and planning around them as best possible. 

[cliffy]

Had a friend flying an unfamiliar 172 (he owned a Cherokee) takeoff after casually switching tanks just before takeoff. Seems the tank selector went to the off position instead of the opposite tank. He got through the run up and takeoff all the way to 100' before it quit. Unfortunately he didn;t have any runway left and put it down off field.

With good orings (4) on the tank caps the chances of water ingress from rain is slight- condensation another matter.

Many Mooney have bad orings. I see it all the time out in the field.  That is the way large amounts of water get in the tank.

I haven't had water in mine in a decade or more and then only a slight amount. 

I switch tanks every 10 gallons (Dynon announcement) 

I usually start and run up and take off  on the left tank as being right handed its easier to switch tanks with one finger

to push to the right tank that way in an emergency.

Some of us are physically challenged to reach down and turn the recessed valve especially from right to left.. 

I have a 1 foot long PVC pipe with notches for the selector handle that I use to ease the effort leaning over to switch tanks.  :-)

As 98% of the time I always leave with full tanks I know I have enough in the left tank after using 10 gallons that if it didn't work

when switched to the other tank, I've still  got enough to get somewhere. 

I guess I'm of the opinion that even if you check it to make sure it works it only tells you it worked that time. No guarantee that it will work

the next time even if you check before takeoff.

As I'm the only one flying my airplane, the last time I swapped tanks it worked fine. Check complete.

Its a purely a simple mechanical valve. Electric valves like in the Boeing are a different animal. 

[PeteMc]

3 hours ago, cliffy said:

I haven't had water in mine in a decade or more and then only a slight amount. 

I actually got a HUGE amount of water when I filled up once.  I'm going to guess it was because there was an issue with the water separator AND it was the time of year with a lot of warming and cooling that can create condensation in any tank, including the supply tank. 

As for switching tanks, I'll often start on one tank and after a little warm-up switch to the other tank for taxi and takeoff.  But never if it is a small airport where it is a matter of minutes from leaving the ramp to takeoff.  I'd really rather have a few coughs at 5k to 15k and switch back to a known good tank than find out just after I've lifted off.

Edited December 13, 2023 by PeteMc

[Pinecone]

9 hours ago, cliffy said:

Had a friend flying an unfamiliar 172 (he owned a Cherokee) takeoff after casually switching tanks just before takeoff. Seems the tank selector went to the off position instead of the opposite tank. He got through the run up and takeoff all the way to 100' before it quit. Unfortunately he didn;t have any runway left and put it down off field.

Difference between fuel injected and carb.  The carb bowl holds a good amount of fuel, so it can take a while to use that.

BUT, he did not follow the checklist, as all high wing Cessna's I have flown you take off and land on Both.

[A64Pilot]

On 12/9/2023 at 3:14 PM, MikeOH said:

I've been thinking about making my own...70 bucks is a little steep for my CB taste

My little C-140 Cessna’s fuel vent system is two 1/8” holes drilled into each fuel cap, factory design, but that was when airplanes cost $5,000 too.

Think if it rains water just might get into the tank?

What I do on the Cessna is take the cheap as in about $3 toilet plungers and unscrew the stick, place the rubber cup part on the caps, it’s heavy enough so that wind wont blow it off and being soft rubber if I get stupid and forget them they wont hurt anything, and they cost about $3 so if I did no great loss.

You might get an odd look for putting toilet plungers on your wing, but they do keep water out.

[Pinecone]

10 hours ago, Schllc said:

Seems like there are good and valid reasons for a variety of methods. 
I am a big fan of routine/consistency.  Not simply for thoroughness, but you can discern and discriminate other issues quicker when you have confidence in your routine. 
I wouldn’t want to have some obvious engine problem like fouling of plugs or mags to make me wonder if it was because I switched tanks and got hyper focused on that deviation from the routine. 
I get as close as I can upon landing to even my tanks. If I add, I add evenly, or top off, always. 

I agree with consistancy.

But, for the last part, do you really prefer to land with 5 gallons on each side versus 10 on one side and near 0 on the other?

[A64Pilot]

18 minutes ago, Pinecone said:

Difference between fuel injected and carb.  The carb bowl holds a good amount of fuel, so it can take a while to use that.

BUT, he did not follow the checklist, as all high wing Cessna's I have flown you take off and land on Both.

Maule fuel selector has four positions. left, right, both and off, each 90 degrees apart so it’s a full circle. Maule uses the same lever Cessna does, except Cessna files the little pointer off and uses the long leg part to point to each selection.

Maule uses the little pointer tip opposite the long leg to point, in Maule’s defense that is how the pointer is designed.

In short many a Maule has landed in a field and I’m sure crashed when pilots revert to earlier learning and place the long part to both like on a Cessna, except 180 degrees from both is off, so they actually turned the fuel off instead of both.

We have a tendency when stressed to revert to earlier training

[A64Pilot]

6 minutes ago, Pinecone said:

I agree with consistancy.

But, for the last part, do you really prefer to land with 5 gallons on each side versus 10 on one side and near 0 on the other?

I was taught years ago that if I was getting low on fuel or even if I thought that fuel just might be an issue to run one side dry in cruise.

That way you KNOW all the fuel you have is in the one tank you’re burning from. The theory is people convince themselves there is more fuel in the other tank than there really is, run out on one, switch over and pretty quickly run out on both. If you know your on the only tank with fuel as it gets low you will be more likely to divert and buy the more expensive fuel as opposed to keep trying for the cheaper fuel, and or when it quits you’ll be more focused on finding a spot to put it as opposed to playing with the fuel selector, boost pump etc.

Thankfully I’ve not yet run both dry yet, have come very close in the Military but not in a Civilian airplane yet.

[Pinecone]

The other reason to run one dry is that you reduce the risk of unporting the fuel pickup on the tank with fuel.

[Schllc]

1 hour ago, Pinecone said:

I agree with consistancy.

But, for the last part, do you really prefer to land with 5 gallons on each side versus 10 on one side and near 0 on the other?

Well, not sure how to answer that to be honest.  Not sure what difference it would make if I was landing...  

I have in the past, just so I knew what how far I could push the gauges, I tried to run a tank dry, the poh says about 3 gallons per tank is unusable, but you can also put an extra few gallons more that the 50 a side.  I was flying with my hand on the selector for about 30 min and couldn't take the suspense any longer and switched.  When I fueled up, it took just over 48 gallons.

I think I could count the times I landed with 10gallons or less on one hand.  I do not like to cut it that close

[jlunseth]

I don’t switch tanks frequently at cruise. My tank switching strategy is driven in part by the accuracy (or lack thereof) of my instruments, and partly by the fact that the plane does not care how far out of balance the tanks might get, it does not slow down or become hard to maneuver, it just ignores any imbalance.

On the ground prior to takeoff, I switch tank three times. I use the fullest tank on startup and on the ramp. I switch tanks to taxi. Then at the hold short I switch back to the fullest tank for the run up and takeoff. This method insures that I have good fuel in both tanks. I have never experienced water in the fuel in my 231, but sure saw it in a rental J with bad cap O-rings several years ago.

Then I fly on the fullest tank for the entire climb, however long that might be. If I go into the flight levels it can be as long as 45 minutes. Once I level off, or if the climb is shorter, when I have used about 10 gallons from the first tank, I switch to the second tank and run on that tank for the next couple of hours. My JPI930 annunciates Low Fuel when a tank reaches 10 gallons, and then there is not way to stop it from showing Low Fuel even when the other tank is full, so I will run the first cruise tank down to just above the 10 gallon mark and then switch. Alternatively, if I am nearing my destination and it is time to begin the descent I will switch tanks for the descent and landing. That way, if something goes wrong with that tank, I know I have another tank with a good ten gallons to make it to the airport.

I use fuel flow to track how much fuel I have, at least on a long trip of a few hours. If I am able to cruise LOP at 11.1-.3 GPH my 75.6 gallons of full fuel is good for around 6 and a half hours, way more than I have ever needed. The on-board bladder(s) can never make it that far. I make a little chart on paper with 37.6 at the top of two columns and then when I switch tanks I get the fuel USD from the 930 and subtract that from the tank, so I know exactly what is left in that tank.

I don’t switch frequently because (1) as I said, the plane does not care, and (2) makes it too complicated to track fuel usage. KISS works best.

I have CiES senders and a JPI 930 so you would think that the fuel gauges would be a great way to track fuel. The senders are certainly better than the old senders, but not so accurate that they beat the fuel flow meter for tracking usage and fuel remaining. Before I started using fuel flow, I tested by flying three consecutive flights of a couple hours, then refilling the tanks myself, to test the fuel flow. Total fuel used was around 50 gallons and the fuel flow meter was .1 gallon off on the conservative side. In other words, I have tested my systems and know which one is more accurate, and then used that to create a really simple method for use in the cockpit that does not require remembering to switch frequently, or to set timers.

I don’t run tanks dry as a matter of course. High altitude restart, according to the POH, may not be simple. The engine may simply not restart until below 12k, if then, because the turbo is not spinning and MP will be very low. I don’t want to ever deal with that, so no tank emptying. I have at lower altitudes emptied a tank out and quickly switched. It is worth doing so you know how much fuel your tanks really hold, as opposed to what is in the POH. You would be surprised.

Edited December 13, 2023 by jlunseth