Which of the following lists the four types of engine fire detection systems?

Which of the following lists the four types of engine fire detection systems?

• A. Thermoswitch system; Thermocouple system; Thermistor-type continuous-loop system; Pneumatic-type continuous-loop system
• B. Thermocouple system; Infrared system; Optical smoke detector; Humidity sensor
• C. Thermoswitch system; Temperature sensor array; Pressure-based detector; Electrical fault detector
• D. Pneumatic-type continuous-loop system; Radioactive detector; Magnetic detector; Acoustic detector

Answer: (A)

Engine fire detection in aircraft powerplants relies on sensing heat in the engine area. The four common types are thermoswitch systems, thermocouple systems, thermistor-type continuous-loop systems, and pneumatic-type continuous-loop systems. A thermoswitch system uses a bimetal switch that responds to a specific temperature. When the area reaches that temperature, the switch opens or closes to trigger the fire indication and, if equipped, the extinguishing system. A thermocouple system uses two dissimilar metals that generate a voltage proportional to temperature. The detector monitors this voltage, and a rise above a set point indicates a fire condition. A thermistor-type continuous-loop system places thermistors along a loop around the engine. As heat changes, the resistance of the thermistors changes, and the control unit detects a fire condition anywhere along the loop. A pneumatic-type continuous-loop system employs a sealed, pressurized tube that expands with heat. The expansion activates a diaphragm or switch to send a fire indication signal when a predetermined temperature is reached. Other detector concepts like infrared, optical smoke, or various surface sensors aren’t the standard aviation engine-fire detection types covered in these classifications, which is why they don’t fit as the four recognized system types.

Engine fire detection in aircraft powerplants relies on sensing heat in the engine area. The four common types are thermoswitch systems, thermocouple systems, thermistor-type continuous-loop systems, and pneumatic-type continuous-loop systems.

A thermoswitch system uses a bimetal switch that responds to a specific temperature. When the area reaches that temperature, the switch opens or closes to trigger the fire indication and, if equipped, the extinguishing system.

A thermocouple system uses two dissimilar metals that generate a voltage proportional to temperature. The detector monitors this voltage, and a rise above a set point indicates a fire condition.

A thermistor-type continuous-loop system places thermistors along a loop around the engine. As heat changes, the resistance of the thermistors changes, and the control unit detects a fire condition anywhere along the loop.

A pneumatic-type continuous-loop system employs a sealed, pressurized tube that expands with heat. The expansion activates a diaphragm or switch to send a fire indication signal when a predetermined temperature is reached.

Other detector concepts like infrared, optical smoke, or various surface sensors aren’t the standard aviation engine-fire detection types covered in these classifications, which is why they don’t fit as the four recognized system types.