Sorry i think we jacked this thread from the OP....however... i reported the fuel differences when i got back on the ground, The CFI and i dipped the tanks there was a 20 odd liter difference (both tanks had been equally filled as per the sheet when i took off) so there was a difference,.. he also suggested i was not flying in balance... i was slightly offended being an ex glider pilot 'n' all. :)

However i have gone and looked at the photo's of the trip... (my dad got very snap happy) and...yep the G1000 suite tells me what i need to know... 22 kt crosswind from....you guessed it...the left.... for most of the flight.

soo.... erm...not totally in balance then... even the GPS shows my crab...

Hang on a mo' Kiwi,

Shirley the a/c once cruising aloft doesn't know it's a cross wind ?

mike hallam.

The G1000 bit of the aircraft does :)

Gravity still works in a crosswind wing down crab dunnit?

What a lovely name for an aeroplane, Mike.

Oh, did you mean surely?

FBW

As Mike points out there is a difference between flying in a cross wind and flying out of balance.

Be careful what you trust off a G1000 in a 172 as well, it can only work on the sensor data it has available. In the case of the 172's float based fuel level sensors, that data is often a fairy tale.

Don't call me Shirley....

Plus I asked the instructor exactly how it did the wind calculation. He thought it included an assumption that you were flying forwards, ie motion through the air was in the direction you were headed, ie there was no correction for flying out of balance.

If correct, that says to me that if you choose to fly out of balance you had better not take the G1000's calculation of wind very seriously. I haven't actually experimented by flying the 172 sideways on purpose and seeing how what the G1000 reports for wind changes.

Fuel tanks are not very deep, there cannot be a significant increase in pressure feed down the fuel line.

I always thought that you select the fullest tank if there is an imbalance simply to bring the aircraft back into balance, why select the other tank and make the balance issue worse?

On a 172 with L,R, Both and off settings the fuel will crossfeed in both and off but not in L or R. So if you are flying out of balance with Both selected then you will end up with an imbalance and as has already been mentioned if you park on a sideways slope then fuel will fill the lower tank if Both or Off is selected. Expensive if it is left wing down!

Would only be on very short final - not on cruise.

Use the "Both" position for take-off and landing. In the cruise select the higher tank until the fuel is "balanced" then back to "both". On a long flight you might have to "balance" the fuel more than once. I use an egg timer to remind me to put it back to both.

However, If the lack of fuel is becoming an issue with both tanks below 1/4, it might be a good idea to select left or right tank. Run the engine on that tank until it starts to cough (run dry), immediately select the other tank and find somewhere to land!!!!

Bob.

Maybe it also caused the G1000 to draw more from one of its batteries than the other.

I do hope you are pax, and not a pilot.