Fuel System Flashcards

1
Q

What is the maximum fuel capacity per tank?

A
  • Left wing tank = 7,492 lbs (pressure refueling)
  • Left wing tank = 7,290 lbs (gravity refueling)
  • Right wing tank = 7,492 lbs (pressure refueling)
  • Right wing tank = 7,290 lbs (gravity refueling)
  • Center tank = 4,610 lbs (cannot be gravity refueled)
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2
Q

What is the maximum fuel capacity during pressure refueling?

A

19,594 lbs

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3
Q

What is the maximum fuel capacity during gravity refueling?

A

14,580 lbs

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4
Q

What is the maximum allowable takeoff fuel in the center tank if each wing tank has less than 4,400 lbs?

A

500 lbs

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5
Q

What is the minimum fuel quantity in each wing for go-around?

A

600 lbs and a maximum climb attitude of 10 nose up.

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6
Q

What is the maximum fuel imbalance for the CRJ-700?

A
  • During takeoff = 300 lbs
  • During all other phases of flight = 800 lbs
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7
Q

How is the bulk fuel temperature in the wing tanks monitored?

A

A single temperature probe monitors the temperature of the stored fuel in the right wing tank and displays it on the fuel synoptic page.

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8
Q

What is the source of motive flow for the Transfer Ejectors?

A

The high pressure output of the Main Ejectors

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9
Q

What is the source of motive flow for the Main and Scavenge Ejectors?

A

The high pressure engine driven fuel pump

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10
Q

What will supply fuel pressure to the engines if the main ejector pressure is low?

A

The DC electric boost pumps.

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11
Q

What is the function of the scavenge ejectors?

A

The scavenge ejectors operate by motive flow and transfer fuel from the wing tanks to the collector tanks.

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12
Q

What is the function of the collector tanks?

A

The collector tanks keep a full supply of fuel available to the engines at all aircraft attitudes.

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13
Q

What is the location of the collector tanks?

A

The collector tanks are located in the forward section of the center tank. There is no migration of fuel from the center tank into the collector tanks.

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14
Q

What is the function of the fuel transfer system?

A

The transfer system moves fuel from the center tank to both wing tanks. This is performed by transfer ejectors and transfer valves located in the center tank. Fuel is then moved from the wing tanks to the collector tanks via the use of scavenge ejectors. The main ejectors receive fuel from their respective collector tank and supply fuel to their engine.

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15
Q

What is the function of the transfer ejectors?

A

The transfer ejectors transfer fuel from the center tank to the wing tanks.

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16
Q

What controls the fuel transfer from the center to the wing tanks?

A

The fuel system computer initiates transfer by opening the appropriate fuel transfer valve when the wing tank capacity drops to 94% (7046 lbs). Motive flow from the engine feed manifold passes through the open valve and activates the transfer ejector that move fuel from the center tank to the appropriate wing tank.

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17
Q

When is the fuel transfer terminated after activation?

A

When the respective wing tank is full, the fuel system computer commands the transfer valve closed. The fuel system computer will cycle the transfer system on and off until the center tank is empty.

18
Q

What is the function of the main ejectors?

A

The main ejector takes fuel from its associated collector tank and delivers the fuel to the engine.

19
Q

What is the definition of fuel crossflow?

A

Crossflow is the process of moving fuel between wing tanks to balance the wing tank quantities.

20
Q

What is the function of the fuel crossflow pump?

A

The crossflow pump is a bi-directional pump that is used to transfer fuel between the wing tanks. When crossflow is required, fuel is taken from the high wing tank by the crossflow pump and then sent to the low wing tank.

21
Q

What is the function of the automatic power crossflow system?

A

The power crossflow system provides automatic transfer (crossflow) of fuel from wing to wing to compensate for an imbalance of fuel in the wing tanks. The crossflow is controlled in the automatic mode by the fuel quantity gauging computer whose drivers control a bi-directional crossflow pump in the required direction.

22
Q

When does the automatic power crossflow activate?

A

When a fuel imbalance of more than 200 pounds exists between the wing tanks, the computer starts the crossflow pump. Fuel is taken from the high wing tank and pumped to the low wing tank.

23
Q

When does the automatic power crossflow stop after automatic activation?

A

The crossflow is stopped when the fuel quanity of the previously low tank exceeds the other by 50 pounds.

24
Q

What is the function of the XFLOW AUTO OVERRIDE switchlight?

A

Selecting the XFLOW AUTO OVERRIDE switchlight to MAN on the fuel control panel provides a signal to the fuel computer which inhibits the automatic feature of the power crossflow system.

25
Q

What is the function of the manual power crossflow system?

A

A manual crossflow control is available should the automatic power crossflow system fail. In manual mode, the crossflow pump is controlled by the “AUTO OVERRIDE” and “XFLOW” switchlights located on the fuel control panel.

26
Q

How do the pilots activate the manual power crossflow?

A

Selecting the XFLOW AUTO OVERRIDE switchlight to MAN on the fuel control panel inhibits the automatic feature of the power crossflow system. When the left or right crossflow valve switchlight is selected (low fuel side), the crossflow pump starts and the appropriate low tank is replenished.

27
Q

What is the function of the left or right crossflow switchlight during manual power crossflow operation?

A

When the left or right crossflow switchlight is pressed (low fuel side), it energizes the pump in the desired direction.

28
Q

What is the function of the gravity crossflow system?

A

A back-up gravity crossflow system is available, which interconnects the left and right wing tanks when a gravity crossflow valve is opened. The gravity crossflow valve is controlled by the “GRAVITY XFLOW” switchlight located on the fuel control panel.

29
Q

How can the pilots activate the gravity crossflow system?

A

When the GRAVITY XFLOW switchlight on the fuel control panel is selected, the gravity crossflow shutoff valve opens and a green advisory message is displayed on the EICAS. Fuel then flows through a gravity manifold and the wing tanks are balanced by gravity. The two wing tanks are interconnected, allowing the quantity in these two tanks to equalize.

30
Q

What is the function of the electric fuel boost pumps?

A

The DC electric boost pumps move the fuel from the collector tanks to the left and right engine fuel supply manifolds. The pumps are used to supply the engines for engine starting and serve as a backup during a main ejector failure.

31
Q

What will occur after an engine fuel feed low pressure in either manifold?

A

Pressing the Left Boost Pump or Right Boost Pump switchlight causes both pumps to operate when the fuel computer detects low fuel feed pressure in either fuel feed manifold.

32
Q

When will the boost pumps automatically activate if the switchlights are in the armed position?

A

Should a main ejector pressure fall below 10 psi due to an engine failure or shutdown, the ejector low-pressure switch provides a ground for the pump control relays energizing both boost pumps.

33
Q

How can the engine fuel shutoff valves be operated?

A

They are controlled by the engine FIRE PUSH switchlights located on the glareshield.

34
Q

What fuel tank normally supplies the auxiliary power unit (APU) with fuel?

A

The left collector tank.

35
Q

What is location of the Refuel / Defuel Panel on the CRJ-700?

A

The Refuel / Defuel Panel is on the right side of the fuselage, forward of the right wing.

36
Q

What is the maximum refueling pressure?

A

50 psi

37
Q

What is the maximum defueling pressure?

A

4 psi

38
Q

What is the function of the Magnetic Fuel Level Indicators?

A

The Magnetic Fuel Level Indicators provide a secondary (mechanical) method of measuring the quantity of fuel in the tanks if there is a failure in the fuel quantity-gauging system.

39
Q

What is the location of the Magnetic Fuel Level Indicators on the CRJ-700?

A

The Magnetic Fuel Level Indicators (4) are located on the underside of the wings and the center tank indicator is located on the underside of the wing box.

40
Q

Where is the location of the fuel inclinometers?

A

The inclinometers are located on Circuit Breaker Panel 2 in the cockpit.

41
Q

How is the FUEL USED indication on the Fuel Synoptic page reset to “0”?

A
  • Entering a different total fuel on the FMS PERF page
  • Selecting the POWER switch located on the Exterior Refuel / Defuel Panel to ON
  • Pushing the MENU pushbutton and then the SEL pushbutton on the ECP