Fire Protection

Question 1

Which bus powers the engine and APU fire/overheat detection?

Answer 1

Battery bus

Question 2

Which bus powers all fire extinguishing?

Answer 2

Hot battery bus

Question 3

How many loops for Engine/APU/Wheel Well/Cargo Fire Detection?

Answer 3

Engine - 2
APU - 1
Wheel well - 2
Cargo - 2 (smoke)

Question 4

What are the benefits of a dual loop system?

Answer 4

Redundancy

Question 5

With both loops operating, how many loops must detect a fire to result in a warning?

Answer 5

Normally, both detector loops must sense a fire or overheat condition to cause an engine overheat or fire alert. However if a loop fails that loop is automatically deselected and the remaining
loop functions as a single loop detector

Question 6

Is there a flight deck annunciation of a single loop fault/failure?

Answer 6

NO

Question 7

What are the indications of an engine fire?

Answer 7

• the fire warning bell sounds
• both master FIRE WARN lights illuminate
• the related engine fire switch illuminates
• the related engine start lever illuminates
• all related engine overheat alert indications illuminate.

Question 8

What happens when you pull the Fire Switch?

Answer 8

Pulling the engine fire switch up:
• closes both the engine fuel shutoff valve and the spar fuel shutoff valve
• closes the engine bleed air valve resulting in loss of wing anti–ice to the affected wing and closure of bleed air operated pack valve
• trips the generator control relay and breaker
• closes the hydraulic fluid shutoff valve. The engine driven hydraulic pump LOW PRESSURE light is deactivated
• disables thrust reverser for the related engine.
• allows the engine fire switch to be rotated for discharge
• arms one discharge squib on each engine fire extinguisher bottle.

Question 9

Does the APU continue to run with an APU fire detected?

Answer 9

No

Question 10

What powers the Cargo Compartment Smoke Detection?

Answer 10

cargo compartment smoke detection powered by DC bus 1 and DC bus 2

Question 11

Describe how the cargo bottles function?

Answer 11

Once armed, the first bottle is discharged by pushing the cargo fire DISCH switch. This
results in the total discharge of the first bottle contents into the selected compartment. The second bottle discharge is metered to discharge at a reduced flow into the selected compartment.

Question 12

What powers the Wheel Well Fire Detection and why is this important when completing the fire test before AC power is established?

Answer 12

No. 2 AC transfer bus.

Because the test light will not function until bus powered