Engine Fire Protection Systems Flashcards
What types of fire detector systems are used for engine fire detection?
Overheat
Rate of rise
Flame detectors
How does a thermal switch fire protection system operate?
When heated past a predetermined temperature, a switch closes and activates the warning devices in the cockpit
How many thermal switches are needed in a thermal switch fire protection system?
At least one
What kind of fire detection system allows more complete coverage than a spot type system?
It continuous loop system
What happens when an engine equipped with a thermocouple fire warning system overheats slowly?
Nothing. Rapid heating is required for this type of fire system to operate.
What is the likely cause of a false fire warning?
Fire sensing loop is bent or kinked
What are fire extinguishing systems designed to do?
Dilute the oxygen around the engine to the point where consumption can’t happen and/or reduce temperatures below the ignition point
Describe how a Kidde and Fenwal continuous loop fire protection systems function:
Kidde- has a sensing element consisting of a sealed inconel tube with two conductors embedded in a thermistor material. One wire is grounded to the outer tube at each end and the other is a positive lead.m when a fire or overheat occurs the resistance of the thermistor material drops, allowing current to flow between the two wires to activate an alarm
Fenwal- has a sensing element consisting of a flexible Inconel tube with a single electrode, surrounded by ceramic beads. The beads prevent the electrode and tube from touching each other. Current is applied to the electrode and the tube is grounded to the aircraft. When a fire or overheat occurs, the core resistance of the ceramic beads drops, allowing currents to flow between the center, electrode and ground, energizing the alarm system.
What elements must be present for a fire to occur?
Fuel
Oxygen
Ignition source
What group of fire extinguishing agents are no longer manufactured after 1995?
Halons
What is the purpose of the discharge cartridge and how is it activated?
To release fire extinguisher agent. A discharge cartridge is electrically fired sending a projectile to break a frangible disc and release the agent.
How are fire extinguishing agents distributed?
Perforated tubing and/or discharge nozzles
How is a fire extinguisher system with a high rate of discharge classified?
As an HRD fire extinguisher system
How is an HRD fire extinguisher agent distributed?
Through open end tubes
How long does it take to discharge an HRD agent?
One to two seconds
How was the fire extinguishing agent in an HRD system distributed?
Through a series of high-pressure tubes
What do the red and yellow discs in a fire extinguishing system indicate?
Red- thermal discharge
Yellow - normal discharge
What is the purpose of a pressure gauge in a fire extinguishing system?
Indicates pressure inside the container. To check if the pressure is within limits, a pressure/temperature chart is used.
What is the proper method for determining the fire extinguisher container pressure?
Container gauge pressure with the pressure/temperature chart will indicate if the pressure is within limits
