Soar to New Heights with the 2025 Commercial Pilot License (CPL) Practice Exam – Ready for Takeoff!

The concept of the critical engine is central to understanding multi-engine aircraft performance, particularly in the context of engine failure during flight. The critical engine is defined as the engine whose failure most adversely affects the aircraft's performance and controllability. For example, in a multi-engine aircraft, if one engine fails, the loss of thrust from that engine can result in a yawing motion towards the dead engine, increasing the workload on the pilot to maintain control. The critical engine is often determined by its position on the aircraft, typically the engine that, when lost, will cause the most significant performance degradation due to factors like asymmetrical thrust.

The specific dynamics vary depending on the aircraft design; for instance, in a conventional multi-engine setup, the engine on the side opposite to the critical engine might counteract the yaw induced by engine failure. Understanding which engine is critical helps pilots plan for engine-out scenarios, ensuring safety and effective handling of the aircraft. Recognizing the critical engine can also influence decisions during engine troubleshooting and performance assessments.

In contrast, the other choices focus on lift production or drag characteristics, which do not address the specific risk and performance implications of engine failure that the critical engine concept embodies. Additionally, the mention of an extra engine for safety reasons does