Varig

 

Sandra Santana

 

Canaviais

 

FIRE PROTECTION - APU FIRE EXTINGUISHING

When there is a fire condition, the APU fire handle switch on the engine and APU fire control panel unlocks. When you pull the APU fire warning handle switch up, a signal goes to these components:   

   APU generator control unit - opens the APU generator breaker    

   APU control unit - shuts down the APU.    

   When you turn the fire warning handle switch right or left, 28v dc goes to the APU extinguisher bottle. This causes the APU fire extinguisher bottle squib to release the extinguishing agent.   

   You get the same results when you use the APU remote control panel P28. When you pull the fire handle switch on the P28 panel, a signal goes to these components:   

   APU generator control unit - opens the APU generator breaker    

   APU electronic control unit - shuts down the APU.    

   The bottle discharge switch also arms.   

   The bottle discharge switch sends 28v dc to the APU extinguisher bottle. This causes the APU extinguisher bottle squib to release the extinguishing agent.   

   When the APU fire extinguisher bottle pressure is less than 250 psi, the pressure switch makes the amber APU BOTTLE DISCHARGED light on the engine and APU fire control panel come on.

EQUIPMENT COOLING SMOKE DETECTION

 EQUIPMENT COOLING SMOKE DETECTION

The supply system and the exhaust system have a smoke detector. The detectors monitor for smoke. Relays give the logic that controls the operation of the smoke detection system.   

   If smoke is detected, the detector sends an alarm signal for these:   

   Indication in the flight compartment    

   Operation of the automatic reconfiguration for the smoke clearance mode    

   Configuration of the purge mode for the supply system.    

   Smoke clearance mode operation has an interface with these operations in the air conditioning system:   

   Flow control and shutoff valve    

   Recirculation fans    

   Equipment cooling fans    

   Overboard exhaust valve.    

   See the air conditioning chapter for more information about those operations (CHAPTER 21).   

   A test panel on the J23 junction box in the EE compartment lets you do a test of the smoke detectors and system operation.

Cargo Smoke Detector system

 

The smoke detectors in the lower cargo compartments are monitored by the cargo electronic units (CEUs). These units process inputs from smoke detectors and interface with the components in the flight compartment.   

   If smoke is detected in the lower cargo compartment, the detector sends an alarm signal to the CEU. The CEU sends the alarm signal to the cargo fire control panel.   

   The cargo fire control panel turns on the FWD or AFT red fire lights and sends an alarm signal to these components:   

   Cabin pressure control system    

   P7 FIRE WARN lights come on    

   Aural warning unit gives the bell sound.    

   The cargo fire control panel sends the alarm signal to the cabin pressure control system. This signal causes the CPC to set the cabin pressure rate of descent to 750 slfpm. This helps prevent smoke penetration into the passenger cabin from the lower lobe. This function is inhibited on the ground.

Smoke Detection

 The function of the smoke detection system is to monitor each lavatory. Smoke detectors are used to detect the visible and invisible combustion particles. 

When the preset threshold is reached, the smoke detector triggers a warning via the Cabin Intercommunication Data System (CIDS).