Chapter 5

Fire Protection

Main Menu

SYSTEM DESCRIPTION

GENERAL

The APU and engines are provided with fire detection, warning, and extinguishing capability. A separate system provides fire and smoke detection and warning along with fire extinguishing capability for the cargo compartments.

FIRE WARNING

An engine fire is indicated by lights in the associated fire control handle and the following aural warnings: A bell sounds for one second, followed by the words "Fire left engine" or "Fire right engine," followed by another bell. The Aural warning continues until the condition is corrected, the BELL OFF button is pushed or the fire control handle is pulled. The red fire control handle light remains illuminated until the condition is corrected.

CARGO FIRE/SMOKE DETECTION

System is not simulated but the panel test does function.

FIRE EXTINGUISHING

There are two fire extinguishing bottles in the aft fuselage. Each bottle has separate discharge heads and distribution lines for each engine and the APU. To discharge a bottle into an engine compartment, pull out on the fire control handle for that engine and twist the handle either left or right. The AGENT 1 (or 2) LOW light between the fire control handles illuminates if the bottle has discharged. To discharge the other bottle, twist the handle in the opposite direction. In addition to arming the fire bottles, pulling a fire control handle closes the respective engine fuel, hydraulic, and pneumatic crossfeed valves; opens the generator control relay; and silences aural fire warnings.

The APU uses the same fire bottles as the engines. To arm the bottles for discharge into the APU, place the FIRE CONTROL switch on the APU panel to OFF & AGENT ARM. This shuts down the APU, opens the APU generator relay, and arms the fire bottles. To discharge the fire bottles, move one fire agent toggle switch to DISCH. As a bottle discharges, the respective AGENT LOW light by the engine fire control handles comes on if Right DC bus power is available.

 

FIRE PROTECTION

 

CONTROLS AND INDICATORS

 

APU FIRE WARNING AND EXTINGUISHING

 

 

LOCATION: Overhead Panel

 

FIRE AGENT SWITCH

 

    OFF - Normal position.

 

    DISCH - Momentary. Discharges fire extinguishing agent into APU compartment from the respective bottle if APU fire control seitch is in 

                   OFF& AGENT ARM position.

 

APU CONTROL SWITCH

 

    NORM - Normal position. Provides control power to APU master shutdown.

 

    OFF &

    AGENT

    ARM  - Shuts the APU ( No 60 second delay) and arms the APU fire agent switches.

 

- Appears when APU fire detection system activated. MASTER WARNING lights also come on.

 

LOCATION: Main Panel

ENGINE FIRE CONTROL

Indicates engine fire or system test. Light stays on until condition is corrected. 

Pulling control:

    Trips generator control relay

    Closes engine fuel valve

    Closes hydraulic shutoff valve

    Closes pneumatic crossfeed valve.

    Silences fire bell and voice warning

 

Rotating control handle discharges selected fire agent into the respective engine compartment.

 

TEST SWITCH

 

Pushing the switch tests the fire detector loop circuits.

 

AGENT LOW LIGHTS

 

Indicates fire extinguisher discharged.

 

This area also has a mouse click area that will refill the agent bottles under the following conditions.

    Aircraft on the ground

    Parking brake set

    Both engines shutdown

 

FIRE BELL OFF SWITCH

 

Cancels engine fire bell and voice warnings.

 

CARGO FIRE CONTROL PANEL

 

 

Pressing the SYSTEM TEST button will test the lights in the cargo fire panel.