C152 fuel imbalance
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C152 fuel imbalance
Is there any reason why a C152 might take more fuel from one tank than the other? I filled both tanks to the top before leaving, and on my arrival the left tank had considerably less fuel in it than the right. In fact the right tank upon inspection had about 6 gallons more than the left!??
The fuel burn was consistant with my planning so it couldn't have been a leak.
Any suggestions??
Cheers
Foz
The fuel burn was consistant with my planning so it couldn't have been a leak.
Any suggestions??
Cheers
Foz
The tanks are linked, so it shouldn't happen.
If you've observed a severe imbalance, there are two obvious reasons:-
(1) You've parked on a slope (but that's a heck of a slope not to notice in a 152).
(2) There is a restriction in the balance hose between the two wing tanks, in which case I'd not fly the aircraft until it's been checked.
You can get a temporary imbalance in the air through flying the aircraft out of balance, but it should settle out quickly once you have started flying with the slip ball in the middle again, or have landed and left the aircraft on a level surface for 10 minutes. But in this case, if you've dipped the tanks after some time on a level surface on the ground and had that large an imbalance, I'd suggest that there's almost certainly a fuel system fault - probably a hose or vent blockage.
G
If you've observed a severe imbalance, there are two obvious reasons:-
(1) You've parked on a slope (but that's a heck of a slope not to notice in a 152).
(2) There is a restriction in the balance hose between the two wing tanks, in which case I'd not fly the aircraft until it's been checked.
You can get a temporary imbalance in the air through flying the aircraft out of balance, but it should settle out quickly once you have started flying with the slip ball in the middle again, or have landed and left the aircraft on a level surface for 10 minutes. But in this case, if you've dipped the tanks after some time on a level surface on the ground and had that large an imbalance, I'd suggest that there's almost certainly a fuel system fault - probably a hose or vent blockage.
G
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Thanks Genghis
Very helpful. While airbourne the guages were showing significant differences after an hour or so which was then confirmed when I landed by visual inspection with a dipstick. I guess this would discount your first theory.
On a different/ but similar note, I am keen to learn more about the technical side of light aircraft so if something like the above takes place I'd know what it was etc. Simply for my peice of mind and I think I would feel more confident as a pilot if I knew more about what I am flying.
Is there a book you would recommend?
Thanks
Foz
Very helpful. While airbourne the guages were showing significant differences after an hour or so which was then confirmed when I landed by visual inspection with a dipstick. I guess this would discount your first theory.
On a different/ but similar note, I am keen to learn more about the technical side of light aircraft so if something like the above takes place I'd know what it was etc. Simply for my peice of mind and I think I would feel more confident as a pilot if I knew more about what I am flying.
Is there a book you would recommend?
Thanks
Foz
For the C152 in particular, there's a reasonable pilots handbook written by Jeremy Pratt and published by AFE which covers how all the systems work and interrelate.
If you want an in-depth understanding of what all the bit do in light aeroplanes in general, then I'd recommend "The Anatomy of the Aeroplane", by Darrol Stinton. It was written based upon his lecture notes when he was a lecturer at the Empire Test Pilots' School in the 1980s(?), before he then went on to be CAA's light aircraft test pilot.
G
If you want an in-depth understanding of what all the bit do in light aeroplanes in general, then I'd recommend "The Anatomy of the Aeroplane", by Darrol Stinton. It was written based upon his lecture notes when he was a lecturer at the Empire Test Pilots' School in the 1980s(?), before he then went on to be CAA's light aircraft test pilot.
G
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As others have said it could be due to a fuel pipe restriction or flying one wing down (unlikely) or when parked the fuel will cross feed into the lower tank.
The 152 takes fuel from through coarse filters at the front and rear inboard corners of the tanks. Then they join up just under the front corner of the doors and each side feeds into the fuel cock (on or off positions only) and then to the gascolator and carburettor. The tanks are joined by a balance pipe which runs behind the carry through mainspar behind the windscreen upper edge.
The starboard fuel cap must be of the vented type and this acts as an inward vent (breather) for both tanks. Many aircraft have had the port cap replaced at some point during their lives for a vented cap as well which doesn't appear to be detrimental to the system operation.
The pipe aft of the strut on the port wing provides a slight positive pressure to the system and acts as an overflow vent. All done through a flapper valve in the port tank (front outboard corner).
The POH has a nice diagram of the system if you like pictures!
The 152 takes fuel from through coarse filters at the front and rear inboard corners of the tanks. Then they join up just under the front corner of the doors and each side feeds into the fuel cock (on or off positions only) and then to the gascolator and carburettor. The tanks are joined by a balance pipe which runs behind the carry through mainspar behind the windscreen upper edge.
The starboard fuel cap must be of the vented type and this acts as an inward vent (breather) for both tanks. Many aircraft have had the port cap replaced at some point during their lives for a vented cap as well which doesn't appear to be detrimental to the system operation.
The pipe aft of the strut on the port wing provides a slight positive pressure to the system and acts as an overflow vent. All done through a flapper valve in the port tank (front outboard corner).
The POH has a nice diagram of the system if you like pictures!
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Once had the pleasure of renting a well-used C150 which only supped from the port tank. An interesting discovery to make while on a night cross-country. . . Over the Everglades. . .
Cue diversion into a deserted Six Toe County Regional Airport at some ungodly time, and a blissful couple of hours spent with the fuel strainer and a half-litre water bottle, decanting juice out of the right tank.
“Oh yes” said the owner when we eventually got home. “It always does that. We only use it for local work.”
It transpired the aircraft had been parked up for some time awaiting a new wing, the port fuel cap had gone AWOL, and no-one had thought to flush the tank before putting it back together.
I learnt about fuel management from that . . .
Cue diversion into a deserted Six Toe County Regional Airport at some ungodly time, and a blissful couple of hours spent with the fuel strainer and a half-litre water bottle, decanting juice out of the right tank.
“Oh yes” said the owner when we eventually got home. “It always does that. We only use it for local work.”
It transpired the aircraft had been parked up for some time awaiting a new wing, the port fuel cap had gone AWOL, and no-one had thought to flush the tank before putting it back together.
I learnt about fuel management from that . . .
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Don't know about the 150/2 but the 182 has only one fuel vent so the aircraft . If the aircraft is flown out of balance air pressure build up at the vent tube stops the cross over breather line between the two tanks from working.
could of course be blockages in the fuel system, but I'd start here.
/L
could of course be blockages in the fuel system, but I'd start here.
/L
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Flown a C150 that always sups preferentially from the left (N-GZ at OBA, otherwise known as "Godzilla"). Pain to fly long distances. However while this can be caused by fuel system problems the most common reason for going out of balance on fuel is flying out of balance, as 182P suggests. Check your ball (if you know what I mean) and if that is central, let someone know about the fuel system.
Most importantly don't spin the aircraft if you think it may be out of balance. Warn the operators and others who fly it, especially on a PPL course where they may spin, that it is feeding unevenly. Not taught well enough in civvy spinning, lateral imbalance might hold even a docile 150/152 in a spin. In the military they teach maximum 3 gallons imbalance of fuel for spinning.
Most importantly don't spin the aircraft if you think it may be out of balance. Warn the operators and others who fly it, especially on a PPL course where they may spin, that it is feeding unevenly. Not taught well enough in civvy spinning, lateral imbalance might hold even a docile 150/152 in a spin. In the military they teach maximum 3 gallons imbalance of fuel for spinning.
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here's a reasonable pilots handbook written by Jeremy Pratt and published by AFE which covers how all the systems work and interrelate.
If you would like one of them, PM me your postal address, send me a cheque, payable to 'The Pprune Fund' for a £5 and I'll post it on to you.
First come - first seved - please indicate which book you want.
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every 150/152 I have ever flow has drawn the fuel enevenly from the tanks. My own 152 draws more from the left tank than the right. On a long flight I can have nearly 2 USG difference on dipping.
This has never been a problem for me and my engineer assures me that it is not a problem and they are renowned as being Cessna experts.
This has never been a problem for me and my engineer assures me that it is not a problem and they are renowned as being Cessna experts.
