FAA Powerplant Written Practice Test

In addition to idle speed adjustment, what other speed must be obtained during carburetor synchronization?

1. Full takeoff rpm

2. Maximum cruising speed

3. Climb rpm

4. Ground idle rpm

The correct answer is: Full takeoff rpm

During the process of carburetor synchronization, it is critical to ensure that the carburetors function properly and provide an even fuel-air mixture to each cylinder across different operating conditions. While idle speed adjustments are necessary for proper engine start-up and low-speed operation, the synchronization process must also include adjustments at full takeoff RPM. This is because during takeoff, the engine is subjected to high power demands, and proper synchronization ensures that all cylinders are receiving the same mixture, which leads to greater efficiency and smooth operation. If the carburetors are not well synchronized at this higher speed, it could result in uneven power distribution, rough engine operation, and potential performance issues during critical phases of flight such as takeoff. The other speeds mentioned either do not apply to the synchronization process or may not reflect the engine's performance under the load conditions typically encountered during takeoff. Thus, establishing synchronization at full takeoff RPM is essential for overall engine performance and safety.