Fuel Cross Feed not working ?

[FlyerC3]

Besides the possibility that I made some other mistake, switching the valve to the open position did not balance the fuel in the tanks. Is this one not implemented ?

[mmerelles]

There is a miss conception i presume.

 

Cross feed valve is not meant to pass fuel one tank to the other but to selectively burn fuel from one side tank to feed the other side engine fuel lines if required.

 

I you want to balance the tanks, you open the cross feed valve as you did and you turn OFF the AC fuel pumps for the left side tank in your case (experiencing lower qty), so the right side tank ac pumps will pressurize/feed left & right engine via the cross feed. Once enough fuel from the right tank is burnt and both balanced, you turn back to ON left tank AC fuel pumps, close cross feed, to resume normal operation

 

Hope this clarifies.

 

Edited April 26, 2019 by mmerelles
misspelling

[FlyerC3]

thanks a lot

[Litjan]

There is one more important thing to know about "crossfeeding":

If you open the crossfeed but have BOTH sides pumps on, fuel will not get evenly burned from both tanks. You would think so - and inititally this was also how the big, official "Level D" simulators that we used for training had it. But they found out in the real aircraft that - since pressures are never EXACTLY the same, the "stronger" side will COMPLETELY "take over". So you yould see that fuel only gets used from one tank, even if all pumps are on and the crossfeed is open.

So just like mmerelles said: If you have an imbalance, open crossfeed, turn off the pumps in the tank with less fuel. We used to say "less fuel, less pressure" to memorize this.

THEN you need to set a reminder (I used to clip the tip of my tie to the card-holder clip on the yoke! ) because its easy to get distracted and then you suddently have reversed your imbalance. We used to call this "fuel yo-yo" .

Cheers, Jan

 

[FlyerC3]

Tanks again

[XPJavelin]

(I used to clip the tip of my tie to the card-holder clip on the yoke! 

 

Great idea for a revision of speedy copilot for ixeg 737

[CharlesCreed]

Luckily the filters rarely need to be changed....not saying they couldnt get dirty....just that its not very common for them to require maintenance.

[marpilot]

So is it possible to move fuel from CTR to LEFT/RIGHT tanks?

[Litjan]

No. You can only use fuel from one tank for both engines - effectively stopping fuel usage from the other tank. To balance the fuel you would open the crossfeed, then turn off the pumps on the tank that is less full.

Cheers, Jan