737 Fire Detection

Question 1

Is it possible to activate the fire suppression system with power to the airplane completely off?

Answer 1

Yes, the bottles are on the hot battery bus. So unless the batteries are disconnected the bottles can still be blown.

Question 2

Explain indications of an engine overheat. What three lights will illuminate?

Answer 2

1. ENG OVERHEAT
2. OVHT/DET
3. MASTER CAUTION

Question 3

Explain function of the Engine Fire Warning switch.

Answer 3

If illuminated it will mechanically unlock (so that it can be pulled)
When pulled up it will arm on squib on each fire extinguisher at which point it can be turned left or right to choose one of the fire extinguishers to discharge.

Question 4

Explain function of APU fire warning switch if there is a fire in the APU what will be the indications?

Answer 4

If illuminated it will mechanically unlock (so that it can be pulled)
When pulled up it will arm the fire extinguisher bottle at which point it can be turned to discharge.

Indications will be the light in the handle, the FIRE WARN light on the panel and a warning bell

Question 5

What does the amber FAULT light mean on the Fire Protection panel?

Answer 5

I* f OVHT DET switch is in normal position the both detector loops have failed.

• If one loop fails with the switch in normal there will not be a FAULT light. However, a fault can still be found by switching to A or B on the DET SELECT switch
• Neither the MASTER CAUTION nor the OVHT DET annunciator lights will illuminate for a FAULT on the engine system ONLY. When there is an APU sensor fault it will show up on the Master Caution light.

Question 6

Explain meaning of the APU DET INOP amber light

Answer 6

The APU sensor loop has failed. Both the MASTER CAUTION and the OVHT/DET system lights will illuminate.

Question 7

What is the meaning of the amber DETECTOR FAULT on the Cargo Fire Panel?

Answer 7

One or more of the detector loops in the cargo compartment has failed.

Question 8

What is the function of the DET SELECT switches on the Cargo Fire Panel?

Answer 8

Crew can choose which loop is active. If one fails the other loop will automatically be the active loop.

Question 9

What are the indications of an engine fire?

Answer 9

• both master fire warning lights illuminate on the panel
• warning bell
• Fire warning switch illuminates
• Engine overheat light illuminates

Question 10

What are the indications of an APU fire?

Answer 10

• both master fire warning lights illuminate on the panel
• warning bell
• APU fire warning switch illuminates
• APU shuts down automatically
• FAULT light illuminates on APU panel.

Question 11

What are the indications of a cargo hold fire?

Answer 11

Warning bell
Both master FIRE WARN lights
FWD/AFT Cargo Fire Warning lights

Question 12

How many fire extinguishers for the APU, Engines and Cargo Hold?

Answer 12

Engines - 2
APU - 1
Cargo - 1

Question 13

What is the indication of an APU fire on the ground?

Answer 13

• RH main wheel well APU fire horn sounds (on ground only) and flashes red