Aviation Mechanic - General, Airframe, and Powerplant › III. Powerplant › Task E. Engine Fire Protection Systems

AM.III.E.S4

Skill

Inspect fire detection thermal switch or thermocouple system.

Study note

Get a short, cited explanation of this element written from the FAA handbooks: the core idea, the numbers that matter, common test traps, and a quick self-check.

From the FAA library

Aviation Maintenance Technician Handbook - Powerplant p. 9-2
Chapter 9: Engine Fire Protection Systems › Engine Fire Detection Systems › Thermocouple Systems
Thermocouple Systems The thermocouple fire warning system operates on an entirely different principle than the thermal switch system. A thermocouple depends on the rate of temperature rise and does not give a warning when an engine slowly overheats ... slave relay, and the thermal test unit. Such a box may contain from one to eight identical circuits, depending on the number of potential fire zones. The relays control the warning lights. In turn, the thermocouples control the operation…
Aviation Maintenance Technician Handbook - Airframe p. 17-3
Chapter 17: Fire Protection Systems › Fire Detection/Overheat Systems › Thermocouple System
mechanical protection without hindering the free movement of air to the hot junction. If the temperature rises rapidly, the thermocouple produces a voltage because of the temperature difference between the reference junction and the hot junction. If both junctions ... gradual, both junctions heat at the same rate and no warning signal is given. If there is a fire, however, the hot junction heats more rapidly than the reference junction. The ensuing voltage causes a current to flow within…
Aviation Maintenance Technician Handbook - Powerplant p. 9-2
Chapter 9: Engine Fire Protection Systems › Engine Fire Detection Systems › Thermal Switch System
Thermal Switch System A number of detectors or sensing devices are…