Unporting Fuel

Jaybird180

Jaybird180

Final Approach
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Jaybird180
If you're low on gas, in IMC and have to execute a missed with complicated terrain avoidance turns, is there a real risk of unporting fuel? Or can The Greatest Pilot in the World keep it perfectly coordinated with turns at 1.00G in the downward vector (relative to the shiny side) that unported fuel is never a factor?
 
Why do you believe we have a min fuel requirement for IFR?
 
Min fuel requirements don't have unporting in mind. And yes it is possible. A lot of aircraft require a specific min fuel for takeoff and go around for that very reason.
 
On your 172, brief unporting won't stop the engine as there will still be fuel in the lines, and when it settles out, the lines will refill. Also, unless you deviated from the book and are flying the approach with the selector other than in BOTH, if one side unports, the other side will have the fuel piled up over the port.
 
Isn't that why they term "useable" fuel as available to the engine in any "normal" flight attitude. Seems to me if the engine stops because of unporting, you're either in an abnormal attitude or you've exhausted the useable fuel in that tank.
 
Ron et al, the question was intended to be airplane and pilot agnostic.
 
Greg Bockelman said:
Or you are severely uncoordinated.
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This depends on the airplane and can be an actual problem. I don't see it being a huge deal in high wing singles, but on low wings, especially twins, I have seen unporting issues when people will goose the throttle as they are entering the turn to the runway.
 
Jaybird180 said:
Ron et al, the question was intended to be airplane and pilot agnostic.
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I'm Jewish, so maybe I am not the right person to ask about the agnostic pilot side. However, the answer will be aircraft-dependent -- no way to get around that. That is why some planes have warnings about not making a big rolling turn onto the runway for takeoff, but most do not.
 
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Ron Levy said:
I'm Jewish, so maybe I am not the right person to ask about the pilot side. However, the answer will be aircraft-dependent -- no way to get around that. That is why some planes have warnings about not making a big rolling turn onto the runway for takeoff, but most do not.
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Rimshot!
 
Look, when you are flying an airplane "gravity" is not always in the direction of the ground. If you aren't hanging from the belts or sliding off your seat then there's virtually ZERO chance of you "unporting" fuel. Even if you were it would have to be for a time period long enough to evacuate all of the existing fuel in the line from tank to engine.

If you really want to know then try selecting OFF at cruise and time it until the engine quits. I'll give you a hint - it's not gonna happen right away.
 
Silvaire said:
Look, when you are flying an airplane "gravity" is not always in the direction of the ground. If you aren't hanging from the belts or sliding off your seat then there's virtually ZERO chance of you "unporting" fuel. Even if you were it would have to be for a time period long enough to evacuate all of the existing fuel in the line from tank to engine.

If you really want to know then try selecting OFF at cruise and time it until the engine quits. I'll give you a hint - it's not gonna happen right away.
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It's rather fast in my Bonanza. I would describe it as "right away" it happened A LOT faster than I thought it would.
 
bartmc said:
It's rather fast in my Bonanza. I would describe it as "right away" it happened A LOT faster than I thought it would.
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Which proves what? that your Bonanza uses fuel faster than most 172s?

the way the fuel system is designed in a cessna high wing is if you have the selector in "Both" there will aways be a tank feeding fuel.
 
#1. Not all Cessna high wings have a "BOTH" position on the fuel selector.

#2 You can't legaly fly on the "BOTH" position with C-172 serial #'s 28000 thru 17258855, above 5,000 feet MSL, (Reference AD 72-07-02) unless modified by kit SK172-31b or SK172-32.

Follow your aircraft flight's manual is the best advice. Everything else is just opinion.

I agree with Tom, the risk of unporting with IFR reserves, or VFR for that matter, is very low, and the chances that the engine would sputter even more remote. I think you would have to intentionally make such a thing happen.

My next question is, does your bird have a header tank under the floor? I'm not that farmiliar with re-start Cessna products...

Cessna 177, have an engine driven fuel pump and electric standby pump because they could not satisify the carburetor inlet minimum pressure requirements at high pitch angles. The wing being so low and aft in regaurds to the carburetor position. They also have a small header tank under the floor near the firewall.
 
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I found it easy to unport the tank when slipping in for a landing in a Cessna 120 if I was slipping into a tank that was about 1/4 or so full. You would be greeted with a moment of silence if you changed your mind and tried to go around.

But, that's not the kind of thing that the OP was asking about.
 
bnt83 said:
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My next question is, does your bird have a header tank under the floor? I'm not that farmiliar with re-start Cessna products...
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Yes it does.
 

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bnt83 said:
#1. Not all Cessna high wings have a "BOTH" position on the fuel selector.

#2 You can't legaly fly on the "BOTH" position with C-172 serial #'s 28000 thru 17258855, above 5,000 feet MSL, (Reference AD 72-07-02) unless modified by kit SK172-31b or SK172-32.

Follow your aircraft flight's manual is the best advice. Everything else is just opinion.

I agree with Tom, the risk of unporting with IFR reserves, or VFR for that matter, is very low, and the chances that the engine would sputter even more remote. I think you would have to intentionally make such a thing happen
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I wonder how many times you will be doing the missed above 5000' as the first post stated.

The C-150 would be the only Cessna single engine that doesn't have a selector That I can think of.
 
Tom-D said:
I wonder how many times you will be doing the missed above 5000' as the first post stated.

The C-150 would be the only Cessna single engine that doesn't have a selector That I can think of.
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Lots of airports above 5000...


205 doesn't have a "BOTH" position. It's Left, Right or Off. I'm sure there are others.
 
Jaybird180 said:
Or can The Greatest Pilot in the World keep it perfectly coordinated with turns at 1.00G in the downward vector (relative to the shiny side) that unported fuel is never a factor?
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You can be at whatever positive G you want - as long as you stay coordinated and positive G's the fuel won't know what's going on.
 
dell30rb said:
You can be at whatever positive G you want - as long as you stay coordinated and positive G's the fuel won't know what's going on.
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The only way to unport both tanks in the OP's 172 is to spin it so fast that the fuel will be at the outboard end of both tanks. That's pretty much impossible and that's the way it is for all the Cessna high wing aircraft with a two tank system.
Those with Fuel injection that requires a header tank and positive flow fuel pump. I can't think of a single way other than being upside down in the trees.
 
Tom-D said:
The only way to unport both tanks in the OP's 172 is to spin it so fast that the fuel will be at the outboard end of both tanks. That's pretty much impossible and that's the way it is for all the Cessna high wing aircraft with a two tank system.
Those with Fuel injection that requires a header tank and positive flow fuel pump. I can't think of a single way other than being upside down in the trees.
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Although there's a fuel pump in my FI 172S, it's only used for starting and emergency procedures
 
Okay - for the sake of the OP, can we consider that I'm talking about a DA-40, which actually does have the risk of unporting below 10Gals per side and can only draw fuel from one wing-tank at a time.

Dang-it! I think I just answered my own question:mad2:










But this would never happen to the Greatest Pilot in the World
 
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