FAA Aviation Mechanic Powerplant (AMP)Turbine EnginesMedium
A turbine engine nacelle fire detection system uses a continuous sensing element routed throughout the fire zone. As temperature rises anywhere along the element, its electrical resistance decreases, allowing current to flow and trigger the fire warning. What type of system is this?
- AOptical flame detection system
- BContinuous-loop fire detection system
- CThermocouple-type spot detection system
- DRate-of-rise thermal switch system
Show answer & explanationAnswer & explanation
Correct answer: B. Continuous-loop fire detection system
Continuous-loop fire detection systems use a sensing element that runs the length of the fire zone; a thermistor-type core material changes resistance with heat, so any hot spot along the loop can trigger a warning, unlike spot detectors that only sense heat at fixed points.
Why the other options are wrong
- A. Optical detectors sense infrared/UV radiation from flames, not resistance changes.
- C. Thermocouple spot detectors sense temperature only at discrete points, not continuously along a loop.
- D. Rate-of-rise detectors respond to a rapid change in temperature, not a continuous resistance change.
Continuous-Loop Fire Detection
A fire detection system using a sensing element that runs through the engine fire zone, changing electrical characteristics (resistance or capacitance) with heat to trigger a warning anywhere along its length.
- Detects fire/overheat anywhere along the loop, not just at fixed points
- Common types: thermistor (resistance decreases with heat) and capacitance-type elements
- Preferred for large coverage areas like engine nacelles
Memory trick: Continuous loop = a fire alarm wire that never sleeps along its whole length