FAA Powerplant Written Practice Test

How does the EFCU use feedback from the engine?

1. A To adjust fuel mixture only

2. B To refine control signal outputs

3. C To detect engine wear

4. D To communicate with pilot instruments

The correct answer is: B To refine control signal outputs

The Electronic Fuel Control Unit (EFCU) uses feedback from the engine primarily to refine control signal outputs. This feedback might include data from various sensors such as pressure, temperature, and airflow measurements, which help the EFCU make precise adjustments to the fuel flow and optimize engine performance. By continuously evaluating the engine's operational conditions, the EFCU can fine-tune its control signals to achieve the best possible efficiency, power output, and responsiveness across different operating conditions. This level of feedback allows the EFCU to ensure that the engine runs smoothly and efficiently, adapting to changes during flight or varying environmental conditions. The other choices describe functions that are either too limited or not directly associated with the primary role of the EFCU. For example, while detecting engine wear is important, it is not the EFCU’s main function, and it does not communicate directly with pilot instruments in the same way the EFCU interacts with engine components. Adjusting only the fuel mixture does not encompass the full range of adjustments made by the EFCU, which considers multiple factors in the engine's performance.