How did the condition levers cause the aircraft to lose thrust?

Question

Accepted Answer

Condition Levers Mistakenly Set to Feathering Position Led to Thrust Loss

The loss of thrust in the Yeti Airlines ATR 72 crash was caused by the pilots mistakenly placing the condition levers in the feathering position. This action, stemming from a lack of awareness and adherence to standard operating procedures, resulted in the aircraft's engines idling and failing to generate the necessary power for flight. The aircraft continued to fly for up to 49 seconds on momentum alone before impacting the ground.
Function of Condition Levers and Feathering Position

Condition levers are critical controls that manage engine power. In the context of aviation, the "feathering position" for propeller engines is a specific setting where the propeller blades are rotated to align with the direction of airflow. This action significantly reduces aerodynamic drag and stops the engine from producing thrust, essentially idling it. The investigation report indicates that the pilots, instead of selecting the appropriate flap lever for landing, inadvertently moved these condition levers to the feathering position.
Impact on Engine Performance

When the condition levers are placed in the feathering position, the engines are effectively shut down from producing significant power. This means they "run idle and not produce thrust," as stated by an investigating panel member. Thrust is the forward force generated by the engines that propels an aircraft through the air and maintains its speed and altitude. Without this thrust, especially during the critical landing phase, the aircraft relies solely on its existing momentum.
Aerodynamic Stall Due to Loss of Thrust

The consequence of the engines idling and not producing thrust is a loss of airspeed. As the aircraft slows down due to the absence of forward propulsion and continued drag, it can eventually reach a point where the wings can no longer generate sufficient lift to counteract gravity. This condition is known as an aerodynamic stall. While the aircraft in this incident flew for approximately 49 seconds after the thrust was lost, this period was insufficient to recover from the stall and prevent the ground impact.
Deficiency in Standard Operating Procedures

The report highlights that the pilots' actions were attributed to a "lack of awareness and lack of standard operating procedures." Standard operating procedures (SOPs) are meticulously designed checklists and protocols that pilots follow during all phases of flight, particularly during critical maneuvers like landing. These procedures are established to ensure safety and prevent errors. The failure to follow the correct SOPs for landing, specifically regarding the correct lever selection, directly led to the misconfiguration of the condition levers and the subsequent loss of thrust.

Reading history

Hide →

This history is cleared when the page is closed.

How did the condition levers cause the aircraft to lose thrust?

Loading

Was this article helpful?

Helpful

Not helpful

Report an issue

1

0

0

Share with friends