The critical engine concept applies to which engine type in modern aircraft?

• A. Turboprop only
• B. Turbofan only
• C. Piston engine only
• D. Jet engine only

Answer: (A)

The critical engine concept focuses on which engine’s failure would cause the greatest adverse effect on an aircraft’s performance and handling due to asymmetrical thrust and related propeller effects. This is a concern for propeller-driven multi-engine aircraft, where losing one engine can produce significant yaw and control challenges because the remaining propeller’s aerodynamics interact with the air differently than a jet’s would. Modern aircraft that are propeller-driven are turboprops, so this concept is most relevant to that engine type. Jets (turbofans) and piston-engine twins don’t exhibit the same propeller-induced asymmetry, so the concept isn’t framed around them in the same way. Therefore, the critical engine concept applies to turboprop engines.