How does the fuel control respond to changes in ambient conditions to maintain speed?

• A. It increases fuel flow when altitude increases regardless
• B. It reduces fuel flow when temperature rises
• C. It adjusts fuel flow based on altitude/temperature inputs to maintain target RPM or power
• D. It locks the fuel flow constant regardless of environment

Answer: (C)

When ambient conditions change, the fuel control uses sensors for altitude and temperature to adjust the fuel schedule so the engine can hold the desired speed or power. Air density drops with higher altitude or hotter temperatures, so to keep the same RPM or thrust, the control increases fuel flow to compensate for the reduced air mass entering the compressor. Conversely, cooler, denser air at lower altitude requires less fuel to reach the same speed. This adjustment is part of a feedback loop that also uses engine speed (and other parameters) to ensure the target speed is maintained within safe limits.