Flying with no fuel in one wing

[yvesg]

Hi guys,

 

Did anyone ever fly their Mooney with one tank full (or almost full) and the other one empty?

 

One of my two tanks just got a re-seal and will sit in a hangar for some time so I thought I should wait to re-fuel (allowing it more cure time). I need to ferry the aircraft to that another location where it will stay put.

 

My plan is to fill the tank 75% full max on the side that did not get touched which will provide me enough time to get where I need to go. Is there any risk fuel could travel to the empty tank? Aircraft is an M20C 1965. Fuel selector does not have both... it is either left or right.

 

I need to know if anyone did something like this and how the aircraft behaved?

 

 

Thanks.

 

Yves

C-FQKM

[AndyFromCB]

Have you ever flown with that kind of imbalance? I've done it in a Cherokee once, and it ain't pretty. The aircraft does not behave well and you do risk running out of aileron for landing if the wind conditions are just right.

[yvesg]

Have you ever flown with that kind of imbalance? I've done it in a Cherokee once, and it ain't pretty. The aircraft does not behave well and you do risk running out of aileron for landing if the wind conditions are just right.

No I have not... and this is why I am asking for opinions before I attempt this and break my neck. I'll try to compute how much weigth I would need in the right seat (of course the empty wing is the right hand side one !!) to help compensate for this. If this is too risky, I will just change my plans.

 

Yves

[aaronk25]

I've ran 1/2 tank and nothing in the other before but, precious comments are right too you will have your hands full.

Not sure if you really have to wait longer for "cure" it's only a couple days. But I wouldn't fly with more than 1/2 load of imbalance.

I like my life, most days.

[jlunseth]

I use one full tank and one mostly empty tank for short flights where I am going to have four good sized people in the aircraft.  That challenges the useful load, and I find I need to carry 40 something gallons (around 240 lbs.) instead of the normal 75.6.  My tank gauges, as I have said in another thread, get squirrely when the tanks have somewhere between 5 and 10 gallons remaining, which means that as much as 15 or 20 gallons of that 40 would require me to operate with the tank gauge reading 0 if I were to start out with equal fuel in each tank.  I can do that with very good fuel flow tracking, but it raises the pucker factor and not something I want to get into with a plane load of passengers.  So I will put, say 5 gallons in one tank and fill the other.  Of course, I am planning on burning off a fair amount of the fuel in the tank that starts out full.  At least I know that I will get 30 gallons of burn before I see 0 on any gauge, and I know I have the 5 in the other tank if I need a reserve.

 

 

I do not switch tanks often during any flight.  On a typical long cross country of say 4 and a half hours, I will burn one tank until I reach cruising altitude.  I am operating at 100%HP during the climb and not leaned out, so the fuel flow is around 20-22 gallons.  The climb may take 35-45 minutes to get to 21k, plus some time that ATC keeps me down at lower altitudes until clear of the MSP Bravo and some time for taxi operations on the ground, so I have probably burned 20 gallons on that tank (out of 37.5) by the time I get set up for cruise at altitude.  When I make my cruise power settings I note the fuel used in the first tank, then switch to the second.  So at that point I am flying with 37.5 in one tank and 17.5 in the other.  I will burn the second tank down to 0 or near zero on the gauges (which means I have 5-10 gallons left in the tank), then switch back to the first tank for approach to landing.  When I make that switch, I am flying with 17.5 in one tank and let's say 7 in the other.  By the time I land they are nearly balanced.

 

 

The plane does not misbehave when flown in this way.  One wing may be higher than the other, but that is it.  I remember trying something similar in a Warrior once and it felt like being perched on a wall, if you let it tip too far in one direction it was going to fall over.  The Mooney is nothing like that.  The AP has no problem flying straight and level, nor do I have an issue if I hand fly.

[co2bruce]

I have flown 1st tank for 1.5 hours (25 gallons) before switching and it was ok. In the Eagle each side holds 37.5 gal. I don't think I would fly much more out of balance. 

 

 

[Steve65E-NC]

After a tank repair on one side, I flew my E with full on one side and empty on the other so the repair could cure. Two souls on board. I do not recall any abnormal behavior or handling problems. The redundancy safety factor of two tanks is lost. But, not all airplanes have more than one tank anyway. I probably would not load up with four people just because of that little additional risk. On the other hank, I think the big risk with tank reseals or repairs is shreds of old sealant getting past the gascolator or primary filter. A second tank does not help much there. So, I would try to control "souls on board" risk for a while after any tank work.

Steve65E-NC

[Hank]

When I had my tanks resealed almost 18 months ago, they kept the plane for ~ 5 weeks. The day I was scheduled to pick it up, it had been sitting full to the caps for several days with no leakage. I flew directly home in 2 legs [stopped for lunch & fuel], and have made no changes to how/when I fill up.

 

Since the whole thing required airline travel, I did not want to have the job almost finished, and gladly bought tickets that would allow for issues during the work. What's another week of downtime vs. airline ticket cancellation and short-term purchase?

 

I also have never flown that far out of balance. When traveling, I change tanks every hour; when loaded heavily with passengers, I partially fill both tanks pretty evenly, so I don't have to try to remember which tank has how much at the start. It all goes by my watch anyway.

[John Pleisse]

Search this topic on M-S. There was a very lively thread about a year ago where several among the group purported the practice of flying one side dry and allowing the engine to sputter or quit, often needing a restart.......all in the name of efficiency and range. Some felt knowing precisely where their reserve would be was mission critical.........it was a comedic nano discussion of pilot bravado. Fun read.

[yvesg]

Search this topic on M-S. There was a very lively thread about a year ago where several among the group purported the practice of flying one side dry and allowing the engine to sputter or quit, often needing a restart.......all in the name of efficiency and range. Some felt knowing precisely where their reserve would be was mission critical.........it was a comedic nano discussion of pilot bravado. Fun read.

Would you have the link? I tried but was unsuccessful locating this thread.

[201er]

I regularly fly my M20J with a 20 gallon disbalance no problem. I've probably gone as far as a 35 gallon disbalance and it was definitely leaning one way but still 100% controllable and responsive. Then again you probably only can take 32 gallons. However, I'd be less thrilled about taking off with that much disbalance. When I was clearing a tank out for work, this was done in air. No experience taking off with over 20 gallons difference.

[aviatoreb]

Search this topic on M-S. There was a very lively thread about a year ago where several among the group purported the practice of flying one side dry and allowing the engine to sputter or quit, often needing a restart.......all in the name of efficiency and range. Some felt knowing precisely where their reserve would be was mission critical.........it was a comedic nano discussion of pilot bravado. Fun read.

 

Ah yes - I remember that one - good times here on Mooneyspace.

[Dale Logsdon]

the fuel tank selant that i use has a 48 hr. full cure time and then you can fill your tank full with no worries.

[201er]

Search this topic on M-S. There was a very lively thread about a year ago where several among the group purported the practice of flying one side dry and allowing the engine to sputter or quit, often needing a restart.......all in the name of efficiency and range. Some felt knowing precisely where their reserve would be was mission critical.........it was a comedic nano discussion of pilot bravado. Fun read.

I'll sum it up for you... It's safer to run a tank dry when it is expected in cruise than it is to have it happen unexpectedly on approach or go around because you are trying to manage the remaining unknown 5-10 gallons in each tank!

[scottfromiowa]

I do not like going below four gallons on a tank without fuel in other tank. If bad fuel roughness I can switch and get down. Redundancy. Of corse after 1hour switch no big deal. Just ask vender what cure time is and drive on.

[Wistarmo]

Just got some fuel tank work done today by Paul Beck and Weep No More.  Flew back home with an empty tank.  I didn't note any difference at all.

[John Pleisse]

I'll sum it up for you... It's safer to run a tank dry when it is expected in cruise than it is to have it happen unexpectedly on approach or go around because you are trying to manage the remaining unknown 5-10 gallons in each tank!

 

I refute this logic. If you are under 15 gals, you are 11 usable and you would have to call minimum fuel at 5 gals if you filed. You're not leaving yourself a back door...no matter which tank it is in. This would be argued against all day, so it really is personal safety preference, versus flight planning logic (that rarely comes to fruition). If you're cutting it close, you'll need more than fuel.

 

Great fodder for M-S, though.

[201er]

It's hard to actually USE your reserve, should you ever have to (not saying to plan it, but to have it accessible), it is best to know you can use it all. If you have 10 gallons remaining based on your fuel flow or watch, it could be 5 and 5, 4 and 6, 3 and 7, 2 and 8, 1 and 9, or even 0 and 10. Over the span of 64-100 gallons, some seepage, sumping, instrument error, human error, etc, the exactness of those remaining gallons is anyone's guess. So that estimated 10 could be 5 or it could be 15. Why not at least take one unknown out which is what tank it's in. That way you have continuous access to it should you need it.

 

When I'm tight for fuel I always run one tank dry while leaving 20 in the other. I'm on the ground before it's down to 10. However, I could make a go around or a few and be confident that until that fuel runs out, I won't have to worry about swapping tanks again! Having it quit on you when you're down to your last 5-10 and having to swap tanks then is a lot more dangerous than doing it during cruise in a low stress environment with options.

[aaronk25]

When I use to fly a archer with 48 gallons on board and worse overall mpg I made a regular practice of running a hour on one tank then run the other tank completely out.....brrp....blah....brrrrrr....then I would switch back over to the remain tank. In balence of 14 gallons. Piece of cake, but now with the J I only run the tank down to within what I think is a gallon left or so.

Never ran a fuel injected plane our of gas before, I guess since 201er doing it maybe ill try.

The first time starving a engine for fuel in flight, in a plane I've never had the opportunity or balls to do it in is always a special moment. Please restart please start please!!!!!!!!!!! Lol

[carusoam]

Why would FI make a difference in your decision?

The carburetor has a small orifice that could be obstructed if dirt/rust particles were somehow to be able to get past the filters and screens...

One carburetor vs four fuel injectors... Carburetor sounds like a worse option.

Best regards,

-a-

[201er]

Never ran a fuel injected plane our of gas before, I guess since 201er doing it maybe ill try.

Please don't do it on my account, but do think about it. Trying to guess when you have 1 gallon left isn't simple. For all you know there could be 3... that could put you 2 more gallons away from catastrophe should you need it. Running the other tank dry and coming back for the other 2 is more nuts then switching early.

 

Let me share a few very important tips I learned about restarting after running a tank dry:

 

1) Fuel pump on, switch tanks, and be patient

2) Leave all the levers as they were

3) No matter what, don't switch back! You already know the other one is dry.

4) Continue flying the plane5

5) If you're LOP, it may not start back up properly so enrich the mixture till it's running smooth and then relean

 

That last pointer I had to discover on my own when it went out on me and wouldn't fire back up because it was too lean. I can't explain why that happens, perhaps someone else understands it better. Enrich the mixture slowly though, don't just push it in to full rich because at altitude that won't work either. Somewhere near where you were originally but slightly richer is the way to go.

[scottfromiowa]

It's hard to actually USE your reserve, should you ever have to (not saying to plan it, but to have it accessible), it is best to know you can use it all. If you have 10 gallons remaining based on your fuel flow or watch, it could be 5 and 5, 4 and 6, 3 and 7, 2 and 8, 1 and 9, or even 0 and 10. Over the span of 64-100 gallons, some seepage, sumping, instrument error, human error, etc, the exactness of those remaining gallons is anyone's guess. So that estimated 10 could be 5 or it could be 15. Why not at least take one unknown out which is what tank it's in. That way you have continuous access to it should you need it.

 

When I'm tight for fuel I always run one tank dry while leaving 20 in the other. I'm on the ground before it's down to 10. However, I could make a go around or a few and be confident that until that fuel runs out, I won't have to worry about swapping tanks again! Having it quit on you when you're down to your last 5-10 and having to swap tanks then is a lot more dangerous than doing it during cruise in a low stress environment with options.

If you read this and it sounds like a good practice anything I say is a waste. Enjoy yourself.

[scottfromiowa]

Please don't do it on my account, but do think about it. Trying to guess when you have 1 gallon left isn't simple. For all you know there could be 3... that could put you 2 more gallons away from catastrophe should you need it. Running the other tank dry and coming back for the other 2 is more nuts then switching early.

 

Let me share a few very important tips I learned about restarting after running a tank dry:

 

1) Fuel pump on, switch tanks, and be patient

2) Leave all the levers as they were

3) No matter what, don't switch back! You already know the other one is dry.

4) Continue flying the plane5

5) If you're LOP, it may not start back up properly so enrich the mixture till it's running smooth and then relean

Are you serious? Oh, never mind...

 

That last pointer I had to discover on my own when it went out on me and wouldn't fire back up because it was too lean. I can't explain why that happens, perhaps someone else understands it better. Enrich the mixture slowly though, don't just push it in to full rich because at altitude that won't work either. Somewhere near where you were originally but slightly richer is the way to go.

[scottfromiowa]

Try some extra shower time instead. Benefits are great and there really is no downside...you are just cleaner

[jetdriven]

Please don't do it on my account, but do think about it. Trying to guess when you have 1 gallon left isn't simple. For all you know there could be 3... that could put you 2 more gallons away from catastrophe should you need it. Running the other tank dry and coming back for the other 2 is more nuts then switching early.

 

Let me share a few very important tips I learned about restarting after running a tank dry:

 

1) Fuel pump on, switch tanks, and be patient

2) Leave all the levers as they were

3) No matter what, don't switch back! You already know the other one is dry.

4) Continue flying the plane5

5) If you're LOP, it may not start back up properly so enrich the mixture till it's running smooth and then relean

 

That last pointer I had to discover on my own when it went out on me and wouldn't fire back up because it was too lean. I can't explain why that happens, perhaps someone else understands it better. Enrich the mixture slowly though, don't just push it in to full rich because at altitude that won't work either. Somewhere near where you were originally but slightly richer is the way to go.

Flip the electric pump on for a few seconds, give it a few more seconds to stabilize and carry on. I'd rather be landing with ten gallons in one tank than "I think" 5 gallons in each tank and have it run dry on final approach, which is a killer. My totalizer says how many gallons are remaining within 1 gallon, but it doesn't tell you where it is. I have control over that, and I exercise that.