Fire Detection and Protection

Question 1

Where are the Fire detection and extinguishing systems?

Answer 1

• APU
• cargo compartments
• engines
• lavatories.

The crew rest compartment has fire detection, but no extinguishing equipment.

The main gear wheel wells have a fire detection system, but no fire extinguishing system. (The nose wheel well has no fire detection system)

Question 2

How many engine fire extinguishing bottles are there?

Answer 2

There are two engine fire extinguisher bottles. Either or both bottles can be discharged into either engine.

Question 3

How many APU fire extinguishing bottles are there?

Answer 3

There is one APU fire extinguisher bottle.

When the APU fire switch is pulled out, rotating the switch in either direction discharges the extinguisher bottle into the APU compartment.

Question 4

What happens if there is an APU fire in the unattended mode?

Answer 4

On the ground with both engines off an APU fire signal from either APU fire detector loop causes APU shutdown and extinguisher bottle discharge.

Question 5

What is the fire detection equipment for the cargo compartment?

How many and where?

Answer 5

The cargo compartment has 11 smoke detectors.

3 for each lower compartment and 8 for the main deck.

Question 6

How many fire bottles are used in the lower cargo compartment?

What happens when they are discharged?

Answer 6

Five fire extinguisher bottles are installed for lower cargo compartment fire extinguishing

In flight, pushing the CARGO FIRE DEPR/DISCH switch causes the immediate total discharge of two extinguisher bottles into the selected compartment.

After a time delay, the remaining three extinguisher bottles discharge at a reduced flow rate into the selected compartment.

If the airplane lands before all of the bottles discharge, one of the remaining bottles discharges at the reduced rate on touchdown

Question 7

Describe Main Deck Cargo Compartment Fire Suppression

Answer 7

The main deck cargo compartment is a Class E compartment.

Pushing the MAIN DECK CARGO FIRE ARM switch configures one pack off and the other to a low flow mode.

Subsequently pushing the CARGO DEPR/DISCH switch initiates a controlled depressurization to a cabin altitude of approximately 23,000 feet with the airplane altitude at 25,000 feet.

Question 8

Is it necessary to test the fire detection/protection systems during preflight?

Answer 8

No

Question 9

Why is testing the fire systems not required?

Answer 9

Self test on power up and constant monitoring.

Question 10

How many fire detection/overheat loops does each engine have?

Answer 10

There are two detector loops in each engine nacelle. Each detector loop provides both fire and overheat detection

Question 11

What causes a fire or overheat warning?

Answer 11

Normally, both loops must detect a fire or overheat condition to cause an engine fire warning or overheat caution.

Question 12

How many fire warning loops does the APU have?

Answer 12

The APU compartment has dual fire detector loops. There is no APU overheat detection.

Question 13

Does the APU have overheat protection?

Answer 13

No, only fire detection

Question 14

How many loops are required to sense a fire for auto shut down of the APU?

Answer 14

Normally, inflight, both loops must detect a fire to produce a fire warning. In the unattended mode, either detector loop can shut down the APU if a fire is sensed.

Question 15

What happens when you pull an engine fire switch?

7 things

Answer 15

• arms both engine fire bottles
• closes the associated engine and spar fuel valves
• closes the associated engine bleed air valves
• trips the associated engine generators off
• shuts off hydraulic fluid to the associated engine–driven hydraulic pump
• depressurizes the associated engine–driven hydraulic pump
• removes power to the thrust reverser isolation valve.

Question 16

Is a cargo fire a Recall / Memory item?

Answer 16

No, Checklist Item

Question 17

LWR AFT or LWR FWD or MAIN DECK – ARMED –

Answer 17

• turns off both recirculation fans
• turns off the lavatory/galley vent fans
• turns off cargo heat in respective compartment
• turns off electrical power outlets in respective compartment
• commands pack to supply air to flight deck and supernumerary areas only
• turns off the Nitrogen Generation System (N/A N704GT)

Question 18

LWR AFT or LWR FWD – ARMED –

Answer 18

• arms all cargo fire extinguisher bottles
• arms the selected compartment extinguisher valve
• puts the equipment cooling system into the override mode
• turns off cargo air conditioning in respective compartment

Question 19

MAIN DECK – ARMED –

Answer 19

• commands EE cooling to provide pack air to flight deck equipment
• turns off main deck cargo compartment air in-flow
• turns off aft cargo air conditioning supply and exhaust

Question 20

What does the equipment cooling system do when the forward cargo fire switch is armed?

Answer 20

In the override mode when the LWR FWD CARGO FIRE ARM switch is ARMED, the vent valve remains closed, both supply fans remain shut down, and the lower forward cargo heat valve is closed. Cabin differential pressure draws air through the flight deck panels and into the E & E equipment compartment to create a reverse flow of air across the equipment, then through the override valve to an overboard vent.

Question 21

What do we need to be aware of when the equipment cooling is operating in the override mode and we are at low altitude and high ambient temps?

Answer 21

Possible equipment failure from overheat due to low air flow.

Question 22

After fighting a cargo fire would you expect to see the EICAS message go away?

Answer 22

Not immediately because the smoke detectors cannot distinguish smoke from halon.

Question 23

What keeps the EECs (Electronic Engine Controls) powered during a dual engine failure?

Answer 23

PMGs