An engine failure refers to the loss of power from an aircraft engine.1 In multi-engine aircraft, an engine failure while airborne causes yawing and rolling due to asymmetric thrust.2 A single engine failure can result in a performance loss of more than 50%.2 The critical fuel scenario for commercial aircraft often assumes a simultaneous engine failure and loss of pressurisation at a critical point, requiring a descent to a lower altitude.3 Additional fuel is carried to ensure that a suitable aerodrome can be reached after such an event.3 In general aviation, loss of engine power was the top accident cause in 2023, frequently leading to loss of control due to insufficient airspeed and attitude monitoring.1

The engine failure rate for current generation commercial jet aircraft is less than 1 per 100,000 flight hours.2 This rate has significantly decreased from approximately 40 per 100,000 flight hours in the 1960s.2

A simultaneous mechanical failure of both engines, not caused by foreign object ingestion, had not occurred in a multi-engine airplane before the Hop-a-Jet Flight 823 incident.4 Between 2001 and 2010, engine maintenance errors contributed to 35 out of 70 randomly selected fatal general aviation accidents involving in-flight loss of control.5 When one engine is inoperative, fuel consumption increases, and the Point of No Return moves closer to the departure point.3 ETOPS concepts, such as adequate airport, entry point, and critical fuel scenario, are part of the exam, as is understanding how wind or engine failure shifts the Point of No Return and Equal Time Point.3 Candidates are tested on their ability to precisely describe each fuel category and arrange them in the correct order.3