Automatic mixture control compensates for changes in what conditions?

Automatic mixture control compensates for changes in what conditions?

• A. Altitude changes only
• B. Humidity changes only
• C. Changes in pressure and temperature
• D. RPM changes only

Answer: (C)

Automatic mixture control keeps the fuel-air ratio steady as the density of incoming air changes. Air density is mainly set by ambient pressure and temperature: when pressure drops or temperature rises, air is less dense, so the engine would ingest fewer air molecules unless fuel flow is increased. The AMC detects these changes and adjusts fuel to maintain the same mixture, preventing running too rich or too lean. Humidity has only a small effect on density, and RPM changes don’t directly drive the mixture adjustment. So the system compensates for changes in pressure and temperature.

Automatic mixture control keeps the fuel-air ratio steady as the density of incoming air changes. Air density is mainly set by ambient pressure and temperature: when pressure drops or temperature rises, air is less dense, so the engine would ingest fewer air molecules unless fuel flow is increased. The AMC detects these changes and adjusts fuel to maintain the same mixture, preventing running too rich or too lean. Humidity has only a small effect on density, and RPM changes don’t directly drive the mixture adjustment. So the system compensates for changes in pressure and temperature.