Fuel Flashcards
FQGC
Fuel Quantity and Gauging Computer
How many fuel tanks?
5 in total
Left Wing Center Right Wing Left Collector Right Collector
Where are the ducts that vent and pressurize the fuel tanks?
Underneath the wings
What is the purpose of relief valves?
Eliminate possibility of excessive pressures building up within the tanks
How many fuel cross-flow systems and what powers each?
2 systems. 1 gravity, 1 powered.
What does the FQGC do?
Automatically controls refueling, powered fuel cross-flow and fuel transfer
It measures fuel quantity and temperature for display on EICAS
How does the FQGC calculate fuel quantity?
Quantity probes in fuel tank
How does the FQGC know if it’s on the ground or in flight?
Weight on Wheels signal
What does the FQGC do in flight to ensure accurate fuel quantity?
Takes into account effects like Pitch
How will you know if the FQGC loses attitude data?
Status message
What do compensator probes do?
Supply FQGC data which computes fuel density.
Where is the fuel temperature sensor?
In the right wing tank
When will fuel indication change to amber on ED1?
- Excess fuel imbalance
- Wing tanks less than 600lbs
- Total fuel is less than 1200lbs
When is a LO FUEL caution displayed?
- Fuel quantity in either wing tank is less than 600lbs
- Fuel quantity is less than 1,200 lbs
- Both collector tanks are low
What temperature is indicated by the fuel temperature probe?
Bulk fuel temperature in the right wing tank
When will bulk fuel temperature turn amber on the synoptic page?
When the temperatures are colder than -40
When will the temperature of the fuel being delivered to the engines turn amber on the synoptic page?
When the temperature of the fuel is colder than 5 degrees C.
What does it indicate if the fuel filter on the fuel synoptic page is amber?
A fuel filter bypass condition exists
Describe the normal flow of fuel in the fuel system.
Center Tank -> Wing Tank -> Collector Tank -> Engine
How is fuel transferred from center tank to the wing tanks?
Transfer Ejectors
Describe how the FQGC controls the transfer of fuel from the center tank to the wing tanks.
FQGC will automatically open and close Two transfer shutoff valves.
It will open them when wing tank quantity is 94% and close when 97%
Difference between Transfer Ejector, Scavenge Ejector and Main Ejector.
All move fuel from one place to another
Transfer = Center -> Wing Scavenge = Wing -> Collector Main = Collector -> Engine
How is fuel supplied to the engine before start and after start?
Before start: Boost Pump
After start: Main Ejector
By selecting the L boost pump Switchlight ON, _________ to operate if a low pressure condition is sensed.
Both pumps are armed
What does the fuel pass through after the main ejector?
The engine shutoff valve -> Fuel filter -> engine
What will close the fuel shut-off valves?
Pressing an ENG FIRE PUSH Switchlight
Where does the fuel come from for the APU?
The left collector tank
If the APU pump fails, but the APU is running, can it still get fuel?
Yes, it will still draw fuel into the system using suction feed
How can you close the APU SOV?
APU FIRE PUSH switchlight
What is the purpose fo the X-flow pump?
Allows transfer between the wing tanks to correct a fuel imbalance and maintain lateral stability.
If the FQGC detects a fuel imbalance, what will it do?
As long as the XFLOW switch is AUTO, it will activate cross-flow fuel pump to transfer fuel where it needs to go.
What does selecting MAN on XFLOW AUTO OVERRIDE do?
Allows you to manually transfer fuel by using the L/R switchlight.
How would you manually transfer fuel from the left to the right tank.
Press XFLOW AUTO OVERRIDE to MAN, then press the “R” switchlight.
If the cross-flow pump fails, can we still transfer fuel?
Yes, through gravity.
How do we open the gravity cross-flow valve?
By selecting the GRAVITY XFLOW switchlight
How can gravity cross-flow e improved?
Sideslip
Where is the refuel-refuel control panel?
Right wing leading edge root
Why should we never remove gravity filler caps for the wing tanks if the tanks are full or fuel quantity is unknown?
Because the gravity filler caps are located below the maximum fuel lever. Removing them would cause fuel to spill out of the cap
How can the fuel quantity be measured if fuel indicating system is inoperative?
Magnetic level indicators (MLS)
MLS
Magnetic level indicators
How much fuel in:
Each Main Tank: ?
Center Tank: ?
Each Main Tank: 7,492lbs
Center Tank: 4,610lbs
The APU fuel shut-off valve is controlled by?
Manually with the APU FIRE PUSH switchlight
Manually with the APU PWR RUEL switchlight
Can fuel flow from the wing to the center tank?
Nope
What are NACA vents for?
They provide static and dynamic venting of the tanks and help maintain constant positive pressure
FCC
Fuel Control Computer
How does the FCC keep fuel quantity indications accurate when in changing attitudes?
By making corrections based on AHRS information
Where are the collector tanks located?
In the center section of the fuselage near the wing root at the lowest point of the fuel system
Do we have bladder tanks in the CRJ?
No
Where are the pressure relief valves and their purpose?
On the lower wing. They relieve over pressure in the fuel tank at approximately 5 psi
How many ejector pumps?
8
How many scavenge ejector pumps?
4; synoptic page is not updated from the old 200
When is the center tank used?
Normally only when on extended flights
Minimum Limit for bulk fuel on takeoff:
-28C
Limit for fuel entering the fuel filter
5 degrees celsius
Difference between transfer and Cross-Flow
Transfer moves fuel from the center tank to the wings
Cross-flow is used to correct for a fuel imbalance
What does hitting the MAN X-FLOW switch do?
Prevents the automatic X-flow of fuel by the pump. It will turn the pump off if it’s on and prevent it from coming on in the future.
When is XFLOW pump automatically de-energized?
When the lower tank that is being filled exceeds the other by 50lbs.
When using the MAN XFLOW, what tank do you select?
The low one. The tank that will be receiving fuel.
What Items are on the APU DIR BUS?
APU Starter
Refuel/Defuel Control Panel.
The ______ status message appears if the fuel service panel is switched on.
“AUTO XFLOW INHIBIT”
The Fuel Check Valve check conducted on the first flight of the day ensures fuel pressure from the ______ cannot supply fuel to the opposite side engine.
Operating engine’s main ejector.
Aside from the scavenge ejectors, how does fuel enter the collector tanks?
One way flapper valves allow fuel to move by gravity into the collector tank
What prevents outward flow of the fuel during wing low maneuvers?
One-way flow valves attached to the internal wing ribs
Purpose of NACA vents:
provide positive header pressure on the fuel in the tanks
When do the DC electric boost pumps operate?
During engine start sequence and/or when a main ejector fails
FSC
Fuel System Computer
Purpose of FSC
Controls and monitors operation of the fuel system.
How many channels in the FSC and how many are active?
2 channels, 1 at a time, the other standby.
Scavenge Ejectors
Transfer from wings to collectors
Transfer ejectors
Transfer fuel from the center to the wing tanks
