FAA Powerplant Written Practice Test

In a supervisory electronic engine control (EEC), what happens if there is a fault adversely affecting engine operation?

1. Engine performance declines gradually

2. It causes an immediate reversion to hydro mechanical fuel control

3. It disables the electronic control completely

4. It triggers an alert for the pilot only

The correct answer is: It causes an immediate reversion to hydro mechanical fuel control

In a supervisory electronic engine control (EEC) system, if a fault occurs that adversely affects engine operation, the system is designed to ensure safety and maintain engine operation as much as possible. In this scenario, a fault will cause the system to revert to a hydro-mechanical fuel control system. This reversion is a critical safety feature that allows the engine to continue operating even if the electronic control fails or experiences a fault. The hydro-mechanical fuel control can manage fuel flow based on mechanical parameters, which provides a backup mode that is generally more reliable under malfunction conditions. This ensures that the pilot can still maintain some level of control and that the engine does not fail completely. The design of such systems prioritizes safety, allowing for a smooth transition to a safety mode to prevent total engine loss. While engine performance can be negatively affected during this transition, the primary function of reverting to a hydro-mechanical system is to maintain engine operation and safety rather than letting performance decline gradually or disabling the electronic controls completely. Additionally, alerts may be triggered to inform the pilot of the reversion, but that is part of the system’s design to ensure the pilot is aware of any issues rather than being the only action taken.