Fire Protection

Question 1

Extinguishing bottles for Engines 1&2

Answer 1

The E175 has 2 extinguishing bottles (A&B) located at the right hand side of the aircraft.
They are cross connected providing 2 shots for the same engine.

Question 2

Detection Subsystem and fire detectors

Answer 2

Provides protection for the overheat conditions in the engine designated fire zone by the use of fire detectors which are connected to the MAU and generate the related indications in the cockpit.
The fire detectors are installed in dual loop configuration. So as 2 loops are protecting the system, the aircraft may be dispatched in the case one loop is inoperative. During normal operations both loops must detect fire to provide fire alarm in the cockpit.
In case both loops are failed, an EICAS message will be displayed “ENG 1 FIRE DET FAIL”

Question 3

Cockpit Test Button

Answer 3

In case the APU is running, the test should not take more than 10seconds, otherwise the APU will shut-down

Question 4

Extinguishing philosophy

Answer 4

To prevent fuel and hydraulic from flowing into the engine designating fire zone.

Question 5

APU detector subsystem

Answer 5

Uses 2 pneumatic fire detectors to detect a fire or overheat condition in the compartment.
Design and function is similar to the Engines 1&2 system.
Detectors are connected to the MAUs 1&3 to supply indication in the cockpit

Question 6

APU fire system operation

Answer 6

A fire is detected and red striped bar (EMER STOP) is illuminated in the the cockpit. By pressing it the red changes to white bar and the APU extinguisher button will illuminate.
If a fire occurs and the EMER STOP button is not pressed within 1minute, the APU fire extinguish button will illuminate.
In the event a fire happens on the ground the APU will shutdown automatically after 10seconds if there is no commanded selection from the cockpit.

Question 7

APU extinguishing bottle

Answer 7

There is one located at the rear of the aircraft in the APU compartment. In case of a failure, an EICAS message will be visible.

Question 8

EMER STOP APU button

Answer 8

It switches off the shutoff valve and a message appears on EICAS.
The shutoff valve may be reopened by pressing again the button and turn the knob to the ON position.

Question 9

Cargo compartment smoke detection subsystem

Answer 9

Is designed to detect smoke in the cargo compartment and turn off the ventilation in the fwd cargo compartment.
Includes a system of ceiling mounted photoelectric fan type smoke detectors and located in recessed trays within the ceiling. Here too the MAU will root the signals to the cockpit.
Rear cargo 2 independent smoke detectors will activate the alarm.
Forward cargo 3 smoke detectors, air circulation fan and cargo compartment shutoff valve. The first smoke detector goes into alarm, the fan operation terminates and the shutoff valve is closed. No cockpit annunciation is activated. The fan remains closed for 60” and the remaining detectors are monitored for 45”. If no further indication happens, an EICAS indication “CRG FWD FIRE SYS FAIL” and treated as a fault. The smoke indication in the cockpit will appear as soon as a second detector is activated “CRG FWD SMOKE”.
In case ONLY one detector is operative in the cargo then for redundant reasons the alarm will alarm automatically without second indication.
When on the ground even with 1 detector alarmed the indication of fire protection fault will be displayed without further waiting.

Question 10

Cargo extinguishing bottles

Answer 10

There 2 at the center of the bay which are used for both cargos.
1 HRD (high rate discharge) 13lb Halon 1301
1 LRD (low rate discharge) 22lb Halon 1301
By pressing the button from the cockpit the HRD is activated and the LRD will be activated after 60 seconds to prevent fire from reigniting but it can be activated manually by pressing the extinguishing button again. The light on the button will go of after the LRD bottle is used but the indication of smoke on the EICAS will remain until the fire is extinguished.
When on the ground the button must be pushed twice to discharge the LRD bottle and if is not pushed within 2’ then the system resets.

Question 11

APU Fire Ex Button

Answer 11

• Closes APU fuel SOV
• Discharges extinguisher
• Shuts down APU through FADEC
• EICAS message APU FIREX BTL DISCH

Question 12

Pulling Fire handle

Answer 12

SOV fuel OFF
Hudraulics OFF
Associated Engine OFF
Associated Bleed air OFF
Cross bleed SOV OFF