BBD-700 Fuel System Review

Question 1

What is the maximum permissible fuel imbalance for on ground and during takeoff and landing?

Answer 1

1100 lbs 20,250 fuel tank load

Question 2

What is the maximum permissible fuel imbalance during flight?

Answer 2

1100 lbs

Question 3

What is the maximum useable fuel load for each fuel tank (pressure refueling)?

Answer 3

Wing – 15,050 lbs per tank
Center – 11,150 lbs
Aft Aux – 2,300 lbs
Total load – 43,550 lbs

Question 4

Fuel in the center tank must be considered unusable unless?

Answer 4

Each wing is full at departure and

Planned cruise altitude is greater than 30000 ft.

Question 5

Fuel in the aft tank must be considered unusable unless?

Answer 5

Each wing contains at least 5500 lbs. fuel at departure and

The planned cruise altitude is greater than 30000 ft.

Question 6

If use of the centre / aft tank is planned, what is the minimum tank fuel load?

Answer 6

500 lbs to ensure xfer pump reprime

Question 7

What is minimum G/A fuel?

Answer 7

600 lbs. per wing

Note: Level flight and Maximum 10° nose up

Question 8

What are the limitations when using wide cut or CIS fuels?

Answer 8

Operation limited to 13,000 feet until the bulk fuel temperature is below 15° C

Question 9

What are the 2 limitations associated with the FRTT (fuel recirculation ) ?

Answer 9

FRTT is prohibited when using wide cut fuels

Asymmetric operation is prohibited

Question 10

What is the minimum engine fuel temperature indication for takeoff?

Answer 10

+5° C

Question 11

When must the Fuel Crossfeed

be selected “OFF”?

Answer 11

Takeoff and Landing

Question 12

Which fuel tanks cannot be gravity refueled?

Answer 12

Forward (XRS) or aft aux tanks

Question 13

How is positive fuel tank pressure maintained during flight?

Answer 13

Ram air via NACA scoops

Note: On ground, NACA scoops provide tank ventilation

Question 14

Do not test operation of the pressure relief valves when?

Answer 14

Wing tank above 11,800 lbs

Center tank above 8,000 lbs

Question 15

What does the FMS “COMPARE FUEL QUANT” message indicate?

Answer 15

2% or greater difference between FMQGC and FMS fuel quantity reading
Note: 2% of the BOW equals 1020 lbs

Question 16

When does FRTT (fuel return to tank) automatically operate?

Answer 16

Above 34,000 feet and
Single fuel temp sensor below -20° C
or
Average of all temp sensors below -9° C

Question 17

When do the AC wing boost pumps operate?

Answer 17

ENG RUN switches to “on”

Crossfeed Shutoff Valve selected “Open” during single engine operation

Question 18

Where is the fuel SOV located and how is the valve closed?

Answer 18

Located behind the aft pressure bulkhead

Closed via the associated fire discharge handle

Question 19

When does fuel transfer from the center tank to the wing tank start?

Answer 19

Wing tank quantity below 93%

Continues until wing reaches full (3% of volume)

Question 20

When does fuel transfer from the aux tank start?

Answer 20

Wing tank falls to 5,500 lbs

Question 21

When does the wing DC aux fuel pump operate automatically?

Answer 21

One or both AC pumps low pressure
Flap position > 0
In flight with landing gear down & locked
Low fuel condition

Question 22

When will the AC boost pumps operate regardless of the ENG RUN switch position?

Answer 22

XFEED SOV to open

Note: This ensures balanced fuel during SE operation

Question 23

Which wing tank normally provides fuel for the APU?

Answer 23

Right wing tank

Question 24

Which fuel pumps operate autonomously (no pilot control)?

Answer 24

Center tank transfer pumps

Question 25

How is fuel moved from the forward aux fuel tank to the center tank (XRS)?

Answer 25

Transfer ejector receiving “motive flow”
and / or
Via gravity flow at a slower rate

Question 26

When is wing transfer automatically initiated?

Answer 26

Lateral fuel imbalance of 400 lbs or more

Question 27

When is wing transfer inhibited?

Answer 27

Flap position > 0
In flight with landing gear down & locked
Low fuel condition

Question 28

Why must the crew monitor “manual” operation of the wing to wing transfer system?

Answer 28

No automatic shutdown of the manual system or overfill protection

Question 29

Where is power for the Refuel/Defuel panel taken?

Answer 29

APU battery direct bus

Question 30

During the refuel SOV test, what does display of the “SOV FAIL” message indicate?

Answer 30

Fuel flow will not stop when the tank is full