Automatic Fuel balancing

[imemyself 12]

It's my understanding that when the fuel crossfeed is in "auto" mode, the CRJ will automatically balance the left / right fuel tanks over time.

 

After takeoff, I've usually had an imbalance of a few hundred lbs, I assume from APU fuel usage.  Even after 30 minutes or more of cruise-time, the fuel still appears to be imbalanced.  When I manually turn the pumps on the balance it, the fuel balances just fine.

 

Has this been implemented?  Or does it only kick in at a certain threshold of imbalance?  Or am I misunderstanding how this actually works in the real aircraft?

[IGrant 51]

From my experience with the real plane having fueled more of them I care to remember as a ramper, the gravity x-feed is basically just a connection between the tanks that opens and nothing more.  I used to ask the pilots to hit it for me when I had to over wing one on my own because it would feed fuel from the wing I was fueling to the other wing and buy me some time and effort.  That said, it transfers really, really slow. Maybe 200lbs a minute at the most.  I'd imagine that whilst flying, banking one way or the other would affect the cross flow.

 

Again, this is purely my experience with the aircraft not based on any actual systems training on the aircraft. None of the airline specific overwing fueling procedures mention using the gravity x-feed.

[imemyself 12]

I have no experience with the actual aircraft, but was basing my understanding on volume 5 of the docs that aerosoft includes.  It mentions an automatic xflow pump, and says in auto mode "a computer monitors imbalanced and starts equalizing on its own".  I think this is separate / in addition to the gravity based xflow?

[IGrant 51]

6 hours ago, Propane said:

Yes, there is a powered crossflow that should kick in automatically.

 

Now that you mention it, I think that is correct.  Sometimes the plane would automatically correct fuel imbalances while doing a single truck overwing and totally throw off your calculations.  That's also interesting because there is a rather large taxi and ramp imbalance allowance as well.  800/1500lbs IIRC.  It's been well over a year now so my memory has faded some. I work with Learjets now which are too easy.

[JRBarrett 675]

On the CRJ-200 there is a curved level gauge (similar to the slip/skid indicator in a GA aircraft) mounted on the back wall of the flight compartment which will show if the aircraft is "leaning" to one side or the other due to a lateral imbalance. I don't know if the 700/900 is equipped with that - perhaps Propane knows.

 

Jim Barrett 

[djd565 6]

46 minutes ago, JRBarrett said:

On the CRJ-200 there is a curved level gauge (similar to the slip/skid indicator in a GA aircraft) mounted on the back wall of the flight compartment which will show if the aircraft is "leaning" to one side or the other due to a lateral imbalance. I don't know if the 700/900 is equipped with that - perhaps Propane knows.

 

Jim Barrett 

 

Interestingly the ground pitch and roll bubbles are modeled in the AS version. 

[JRBarrett 675]

3 hours ago, djd565 said:

 

Interestingly the ground pitch and roll bubbles are modeled in the AS version. 

 

So I see! I never thought to look for them.

[realworldcrjpilot 83]

On the actual aircraft the auto Cross flow will engage when you have a difference of 200 pounds on each tanks. It will stop when the tank with less fuel it's 50 gallons more than the tank that initially had more fuel. 

[RandallC 60]

On the actual aircraft the auto Cross flow will engage when you have a difference of 200 pounds on each tanks. It will stop when the tank with less fuel it's 50 gallons more than the tank that initially had more fuel. 

 

Small typo...should read 50 lbs. [emoji1360]