BBD-700 Fuel System Review Flashcards
What is the maximum permissible fuel imbalance for on ground and during takeoff and landing?
1100 lbs 20,250 fuel tank load
What is the maximum permissible fuel imbalance during flight?
1100 lbs
What is the maximum useable fuel load for each fuel tank (pressure refueling)?
Wing – 15,050 lbs per tank
Center – 11,150 lbs
Aft Aux – 2,300 lbs
Total load – 43,550 lbs
Fuel in the center tank must be considered unusable unless?
Each wing is full at departure and
Planned cruise altitude is greater than 30000 ft.
Fuel in the aft tank must be considered unusable unless?
Each wing contains at least 5500 lbs. fuel at departure and
The planned cruise altitude is greater than 30000 ft.
If use of the centre / aft tank is planned, what is the minimum tank fuel load?
500 lbs to ensure xfer pump reprime
What is minimum G/A fuel?
600 lbs. per wing
Note: Level flight and Maximum 10° nose up
What are the limitations when using wide cut or CIS fuels?
Operation limited to 13,000 feet until the bulk fuel temperature is below 15° C
What are the 2 limitations associated with the FRTT (fuel recirculation ) ?
FRTT is prohibited when using wide cut fuels
Asymmetric operation is prohibited
What is the minimum engine fuel temperature indication for takeoff?
+5° C
When must the Fuel Crossfeed
be selected “OFF”?
Takeoff and Landing
Which fuel tanks cannot be gravity refueled?
Forward (XRS) or aft aux tanks
How is positive fuel tank pressure maintained during flight?
Ram air via NACA scoops
Note: On ground, NACA scoops provide tank ventilation
Do not test operation of the pressure relief valves when?
Wing tank above 11,800 lbs
Center tank above 8,000 lbs
What does the FMS “COMPARE FUEL QUANT” message indicate?
2% or greater difference between FMQGC and FMS fuel quantity reading
Note: 2% of the BOW equals 1020 lbs
When does FRTT (fuel return to tank) automatically operate?
Above 34,000 feet and
Single fuel temp sensor below -20° C
or
Average of all temp sensors below -9° C
When do the AC wing boost pumps operate?
ENG RUN switches to “on”
Crossfeed Shutoff Valve selected “Open” during single engine operation
Where is the fuel SOV located and how is the valve closed?
Located behind the aft pressure bulkhead
Closed via the associated fire discharge handle
When does fuel transfer from the center tank to the wing tank start?
Wing tank quantity below 93%
Continues until wing reaches full (3% of volume)
When does fuel transfer from the aux tank start?
Wing tank falls to 5,500 lbs
When does the wing DC aux fuel pump operate automatically?
One or both AC pumps low pressure
Flap position > 0
In flight with landing gear down & locked
Low fuel condition
When will the AC boost pumps operate regardless of the ENG RUN switch position?
XFEED SOV to open
Note: This ensures balanced fuel during SE operation
Which wing tank normally provides fuel for the APU?
Right wing tank
Which fuel pumps operate autonomously (no pilot control)?
Center tank transfer pumps
How is fuel moved from the forward aux fuel tank to the center tank (XRS)?
Transfer ejector receiving “motive flow”
and / or
Via gravity flow at a slower rate
When is wing transfer automatically initiated?
Lateral fuel imbalance of 400 lbs or more
When is wing transfer inhibited?
Flap position > 0
In flight with landing gear down & locked
Low fuel condition
Why must the crew monitor “manual” operation of the wing to wing transfer system?
No automatic shutdown of the manual system or overfill protection
Where is power for the Refuel/Defuel panel taken?
APU battery direct bus
During the refuel SOV test, what does display of the “SOV FAIL” message indicate?
Fuel flow will not stop when the tank is full
