Aircraft Fire Protection Systems Subsystems Quiz

Fire Protection System

• The fire protection system provides detection of smoke, fire, and overheat conditions in various parts of the aircraft.
• It alerts the crew of engine and nacelle fire, APU compartment fire, equipment area overheats, and smoke detection in the baggage compartment.
• The system provides for the elimination of fire in the engine core, engine nacelle, and APU compartment, and portable fire extinguishers for fire in other areas.

Subsystems

• Engine and Auxiliary Power Unit (APU) Fire and Overheat Detection and Warning System (2A-26-20)
• Engine and APU Fire Extinguishers (2A-26-30)
• Aircraft Interior Overheat and Smoke Detection, Smoke Evacuation, and Portable and Fixed Fire Extinguishers (2A-26-40)

Engine and APU Fire and Overheat Detection and Warning System (2A-26-20)

• The system provides means for detecting and alerting the crew of an overheat or fire condition within the engine and APU areas.
• It consists of dual-element loops in each engine and nacelle, fire detection control units, fire detection and fault test switches, and visual and audible warnings.
• Each engine is equipped with dual-loop fire detectors placed in critical engine areas to sense heat levels associated with fire.
• The APU enclosure is monitored by a single element sensor to detect overheat conditions caused by a fire.

Engine Fire and Heat Sensing

• The engine fire and heat sensing system consists of dual-element loops in each engine and nacelle, two separate fire detection control units, and fire detection and fault test switches.
• The fire detection rail assemblies are constructed of an outer stainless steel sheath, which contains a temperature-sensitive glass/oxide material and a coaxial cable center wire.

APU Compartment Sensing

• The APU compartment sensing system is made up of an APU fire sensor, APU fire detection test relay, APU fire test switch, and an APU fire warning light.
• Fire detection for the APU is provided by a pneumatically-operated thermal sensor assembly.

Equipment Overheat Sensing and Indication

• The equipment overheat sensing and indication system consists of normally-opened thermal switches mounted at various locations throughout the aircraft.
• Closure of any of the switches will route a DC signal to the CAS and will display the appropriate message to the crew.

Fire and Smoke Detection

• The fire and smoke detection system consists of smoke detectors and thermal switches.
• The smoke detector unit is made up of a photoelectric cell located in the baggage compartment.
• The system also includes emergency smoke evacuation valves.

Indication and Test

• The fire detection indication and test system provides the crew with a means to indicate the presence of an overheat or fire condition in protected areas of the aircraft.
• The system includes fire test switches, fire detection fault switches, and fire pull handles.

Circuit Breakers and Indications

• The circuit breakers protect the fire detection and warning system.
• The indications include CAS messages, warning lights, and audible warnings.

Limitations

• There are no limitations for the fire detection and warning system established at the time of this writing.

Engine and APU Fire Extinguishers (2A-26-30)

• The engine and APU fire extinguishing system consists of two identical single-shot fire extinguishing bottles containing a fire extinguishing agent and propellant.
• The fire bottles are discharged using fire handle rotary switches located on the pedestal.### Engine Fire Extinguishing System
• Each bottle contains CF 3 Br (Halon 1301) charged with nitrogen to approximately 600 psi at 70°F.
• The bottles are interchangeable and each has three bonnets.
• Only the left bottle has all three bonnets connected.
• Each extinguisher bottle will discharge its entire contents when fired.

Engine Fire Extinguishing Bottles

• Two fire extinguishing bottles are mounted in the upper part of the tail compartment.
• Each bottle has three electrically-actuated explosive cartridges.
• When the bottles are fired, the cartridges release the bottle contents into the bonnet.

Cartridges and Shot Sequences

• The cartridges represent SHOT 1 and SHOT 2 for the engines.
• On the left bottle, a third cartridge is connected to the plumbing which is routed to the Auxiliary Power Unit (APU).
• The third cartridge is unused on the right fire bottle.
• Electrical power to detonate the right fire bottle (SHOT 1) cartridges is supplied by the left essential DC bus.
• Electrical power to detonate the left fire bottle (SHOT 2) cartridges (excluding the APU cartridge) is supplied from the right essential DC bus.

Fire Extinguishing Plumbing

• On the side of each bonnet is a tubing connection.
• Pressure moves the shuttle valve up to block the top (crossover) line from the extinguishing agent and opening the center port.
• This allows the extinguishing agent to be discharged into the left engine fire zones.

Fire Protection System

• Provides the means for detection of smoke, fire, and overheat conditions in various parts of the aircraft.
• Alerts the crew of engine and nacelle fire, APU compartment fire, equipment area overheats condition, and smoke detection in the baggage compartment.
• Provides for the elimination of fire in the engine core, engine nacelle, and APU compartment and portable fire extinguishers for fire in other areas.

Engine and APU Fire and Overheat Detection and Warning System

• Provides means for detecting and alerting the crew of an overheat or fire condition within the engine nacelle and APU enclosure.
• Provides for crew-activated discharge of fire extinguishing agent to either powerplant nacelle or APU compartment in response to a CAS message.
• Each engine is equipped with dual-loop fire detectors placed in critical engine areas to sense heat levels associated with fire.

Fire Detection System

• Consists of two basic types of detection devices: spot detectors and area detectors.
• The purpose of the fire detection system is to alert the crew of smoke, fire, and overheat conditions.
• Includes engine fire and heat sensing, pylon fire and heat sensing, APU compartment sensing, equipment overheat sensing, and fire and smoke detection.### Engine Fuel Control Fire Detection and Warning Indications
• The fire detection and warning system is protected by several circuit breakers, including APU CTRL 1, APU CTRL 2, FIRE DET APU MCDU SSPC, and others.
• The APU fire detector receives essential DC power through the APU CTRL 1 or APU CTRL 2 circuit breakers.
• The FIRE TEST and FIRE DETECTION switches are operational as soon as power is applied to both DC essential buses.
• The left or right engine fire indication test is performed by pressing and holding the respective switch (L/R ENG FIRE TEST switch).
• The results of the test include illuminated red segments, MASTER WARN reset switch, fire handle, FUEL CONTROL switch, and a three-chime aural warning tone.

CAS Messages

• The following CAS messages are associated with the engine and APU fire detection and warning system:
  • L-R Engine Fire (warning)
  • Engine Fire Loop Alert (warning)
  • APU Fire (warning)
  • Fire Detection Loop Fault (caution)
  • APU Fire Detector Fail (caution)
  • L-R Engine Hot (warning)

Engine and APU Fire Extinguishers

• The purpose of the engine/APU fire extinguishing system is to extinguish fires that may develop within the engines, engine nacelles, or APU.
• The fire extinguishing system consists of two identical single-shot fire extinguishing bottles containing a fire extinguishing agent and propellant.
• The bottles are discharged using fire handle rotary switches located on the pedestal.
• Each bottle contains CF3Br (Halon 1301) charged with nitrogen to approximately 600 psi at 70°F.
• The bottles are interchangeable, and each has three bonnets.

Engine Fire Extinguishing System Operation

• When a fire is detected by the engine fire detection system, power is routed to a lock release solenoid in the fire handle, allowing the handle to be pulled.
• Pulling the handle causes three sets of switches to change position and send a signal to the hydraulic shutoff, electrical power system, and fuel shutoff control.
• This shuts off hydraulic fluid flow, electrical power, and fuel flow to the engine.
• The fire handles incorporate a solenoid release button in the event of a solenoid failure.

Fire Protection System

• The Fire Protection system provides the means for detection of smoke, fire, and overheat conditions in various parts of the aircraft.
• The system alerts the crew of engine and nacelle fire, APU compartment fire, equipment area overheats condition, and smoke detection in the baggage compartment.
• The fire extinguishing system provides for the elimination of fire in the engine core, engine nacelle, and APU compartment, and portable fire extinguishers for fire in other areas.

Engine and APU Fire Detection and Warning System

• The system provides means for detecting and alerting the crew of an overheat or fire condition within the BR725 powerplant nacelle, the adjacent pylon area, and the Auxiliary Power Unit (APU) enclosure.
• Each aircraft engine is equipped with dual-loop fire detectors placed in critical engine areas to sense heat levels associated with fire.
• The engine hot bleed air ducting is also monitored for leaks by thermal switches set at predetermined temperatures to signal overheat conditions.
• The APU enclosure is monitored by a single-element sensor to detect overheat conditions caused by a fire.

Test your knowledge on the subsystems of aircraft fire protection systems, including engine and APU fire detection, extinguishers, interior overheat and smoke detection, and fire extinguishing system diagrams.