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the right sidewall lining of the forward cargo compartment, aft of the cargo door.  [Figure 9-22] 

The two engine fire extinguishing bottles are identical. Each bottle has these following components: 

• A safety relief and fill port 

• A handle for removal and installation 

• A pressure switch 

• Two discharge assemblies 

• An identification plate 

• Four mounting lugs [Figures 9-23, 9-24, 9-25] 

The bottles contain Halon fire extinguishing agent pressurized with nitrogen. If the pressure in the bottle becomes too high, the safety relief and fill port opens so the bottle does not explode. The discharge assembly has an explosive squib. An electric current from the fire extinguishing circuit fires the squib. This releases the Halon through the discharge port. The pressure switch gives flight deck indications when bottle pressure decreases. The switch monitors the pressure inside the bottle and is normally open. When the pressure decreases because of a leak or bottle discharge, the switch closes an indicating circuit. 

## Squib 

The squib is installed in the discharge assembly at the bottom of the fire container. A fire container has two squibs, one for each engine. The squib is an electrically operated explosive device. When the squib is activated, it fires a slug through the breakable disk, and nitrogen pressure inside the bottle pushes the Halon through the discharge port. The squib fires when the fire switch is pulled and turned to the DISCH 1 or DISCH 2 position.  [Figure 9-22] 

## Engine Fire Switches 

The engine fire panel is in the flight deck on the P8 aisle stand. The engine fire panel has a fire switch for each engine and a discharge light for each fire bottle. [Figure 9-26] 

The engine fire switch has four functions: 

• Gives an indication of an engine fire 

• Stops the engine 

• Isolates the engine from the airplane systems 

• Controls the engine fire extinguishing system 

The fire switch assembly incorporates a solenoid that locks the fire switch so that the flight crew cannot pull it accidently. 

