APU Fire Panel

Question 1

If the APU fire PB is pressed what happens?

Answer 1

1. Shuts down the APU
2. Silences the aural warning (CRC)
3. Arms the squib
4. LP fuel valve closes
5. APU fuel pumps turn off (FWD and AFT)
6. Generator turns off
7. APU bleed and XBleed valves close

Question 2

What controls the automatic functions of the APU?

Answer 2

ECB (electronic control box) controls APU flow output etc.

Question 3

What happens automatically if there is an APU fire on the ground? in the air?

Answer 3

APU will shut down and fire extinguisher will be deployed automatically. This will not happen in the air.

Question 4

How many bottles for APU fire fighting?

Answer 4

1 halon bottle

Question 5

What fire detection does the APU have?

Answer 5

2 Gas filled loops.
When the gas expands to a certain degree, it triggers a sensor at a certain threshold.

A Fire Warning will be issued if:
Both loops detect fire.
One loop detects fire and the other is inoperative.
Both loops break within 5 seconds.

Question 6

If the fire goes out will the warnings stop?

Answer 6

Yes

Question 7

If APU fire test button is pressed what happens?

Answer 7

Two master warning lights
APU FIRE Pb warning light
Apu Fire message
Agent squib (white) pb light
DISCH (amber) pb light
CRC (aural)

( 4 red lights/message
1 white
1 amber
CRC)