Final answer:
The A/C system in an aircraft protects against under speeding prop by monitoring and adjusting the propeller speed. This is achieved through devices like governors and propeller pitch control mechanisms. Under speeding can lead to loss of efficiency and potential damage to the engine.
Step-by-step explanation:
In aircraft propellers, under speeding can lead to loss of efficiency and possible damage to the engine. The propeller speed is controlled by the aircraft's engine and is usually optimized for a specific range to ensure maximum performance. The A/C (Automatic Control) system in an aircraft contains various sensors and controllers that monitor and adjust the propeller speed to maintain it within the desired range.
For example, a governor is a device in the A/C system that senses the actual propeller speed and compares it to the desired speed. If the propeller speed drops below the desired range, the governor will adjust the engine's throttle setting to increase power and increase the propeller speed, thus protecting against under speeding.
Other components in the A/C system, such as the propeller pitch control mechanism, can also contribute to protecting against under speeding by regulating the angle of the propeller blades to optimize their efficiency at different speeds.