Description (AMM 26-17-00)

 

A- The wheel well overheat detection system provides overheat detection in the main wheel well area. The detection system is an electrical, heat sensing system that responds to overheat by activating fire warning lights and an alarm bell.

 

B- The wheel well overheat detection system consists of the engine and APU fire control module P8-1, compartment overheat accessory unit M237, alarm bell, master fire warning lights, and a sensing element. The sensing element is connected to the compartment overheat accessory unit, which monitors the resistance of the sensing element. When a temperature rise causes the element resistance to drop to the value corresponding to the alarm temperature, the compartment overheat accessory unit will provide a signal to the wheel well warning light and alarm bell and a ground to the master fire warning lights.

 

C- The overheat detection system can be tested by operation of the TEST switch on the engine and APU fire control module. The switch tests continuity through the wheel well system by simulating an overheat condition and energizing the alarm bell and warning lights.