Oral Prep - Fuel

Question 1

What powers the fuel system ejector pumps (transfer, scavenge, main)?

Answer 1

Motive Flow

Question 2

What does selecting both of the fuel boost pump switch lights on cause?

Answer 2

Arms both boost pumps, and if a low fuel feed pressure is detected, both pumps turn on

Question 3

How can fuel be manually transferred from the left wing tank to the right wing tank?

Answer 3

Normal crossflow is automatic, but manual crossflow is accomplished by selecting the XFLOW AUTO OVERRIDE to MAN, then selecting the wing you wish to send fuel to (R XFLOW). Fuel can also be balanced using the GRAVITY XFLOW valve.

Question 4

When is automatic fuel transfer initiated (wing tank to wing tank)?

Answer 4

When a 200-lb. imbalance exists.

Question 5

How is fuel heated?

Answer 5

Engine oil to fuel heat exchangers

Question 6

In flight, if low pressure is detected in the left engine feed line, which boost pump ON light will illuminate?

Answer 6

The boost pump detecting low pressure will activate itself, and the cross-side boost pump.

Question 7

On the ground, if low pressure is detected in the left engine feed line, which boost pump ON light will illuminate?

Answer 7

Both, if selected ON

Question 8

How is fuel transferred from the center tank to the wing tanks?

Answer 8

Through motive flow (transfer ejectors).

Question 9

Why are both fuel boost pumps selected off for single engine
taxi?

Answer 9

To prevent a fuel imbalance

Question 10

An Amber FUEL IMBALANCE caution message is displayed when?

Answer 10

When the fuel imbalance reaches 800-lbs.

Question 11

Where is engine fuel feed temperature displayed?

Answer 11

On the FUEL synoptic page.

Question 12

Where is bulk fuel temperature displayed?

Answer 12

On the FUEL synoptic page

Question 13

Can fuel be transferred from the center tank to the wing tanks with the engines shut down?

Answer 13

No, needs motive flow (transfer ejectors).

Question 14

What is the purpose of the first flight of the day check of the FUEL Check Valve on the Engine Start Check? Is this valve depicted on the Fuel Synoptic page?

Answer 14

Either boost pump is capable of feeding both engines from their respective collector tank. A common fuel manifold between the boost pumps allows either boost pump to pressurize both the left and right engine fuel feed manifolds. A check valve is installed in between the fuel pump common manifold and the fuel feed manifold downstream of the main ejector. The check valve is installed to prevent the main fuel feed pressure from entering the common duct. This check valve is not represented on the FUEL synoptic page.

Question 15

What is a fuel collector tank and its purpose?

Answer 15

All fuel supplied to the engines passes through collector tanks. The left and right collector tanks are seated inside the center tank at a point lower than both wing tanks. The tanks are kept full by gravity-feed lines to their respective wing tanks and jet pumps when the engines are operating.

Question 16

What are the two methods of fuel crossflow and how do you accomplish each?

Answer 16

The CRJ 200 has two methods of fuel crossflow: powered (auto or manual) and gravity. Powered crossflow is an automatic function accomplished by the fuel computer. If the automatic crossflow fails to maintain balance, the automatic function can be inhibited to allow manual powered crossflow. If powered crossflow fails completely, gravity crossflow can be used to maintain balance. If a fuel imbalance of more than 200 lbs. exists between fuel tanks, the fuel computer energizes the APU/XFLOW pump. Fuel is drawn from both tanks, and the crossflow valve associated with the low wing tank is opened, allowing fuel to flow to that wing. The fuel computer closes the associated crossflow valve and the APU/XFLOW pump stops when the quantity of the low tank exceeds the other tank by 50 lbs. If an imbalance occurs that the automatic powered crossflow does not respond to, the pilot can manually override the auto function. Selecting the AUTO OVERRIDE switch to MAN on the FUEL control panel inhibits the automatic crossflow system. Manually selecting either the left (L XFLOW) or right (R XFLOW) switchlight turns on the APU/XFLOW pump, and opens the associated crossflow valve permitting fuel from both wings to flow to the selected tank. When the tanks are balanced, selecting the XFLOW valve will close the crossflow valve and stop the pump.

Question 17

How many fuel BOOST PUMPS does the CR2 have and how do they work?

Answer 17

Control of the boost pumps is provided with two switchlights: L BOOST PUMP and R BOOST PUMP. Selecting either of the switchlights on, energizes and arms both boost pumps, and if a low fuel feed pressure is detected, both boost pumps turn ON. Following a normal engine start, once motive flow pressure is established on the engines the boost pumps will turn off, but remain in standby should a low pressure condition exist. In-flight, if a low pressure condition exists, both boosts
pumps will turn on. However, turning off the boost pump in-flight that is sensing low pressure will de-energize the selected pump and place the cross-side pump back into standby.