HOW DO HELICOPTERS GET TO THE GROUND WHEN THEY HAVE AN ENGINE FAILURE
When a helicopter experiences an engine failure, pilots rely on a critical maneuver called autorotation to safely bring the helicopter to the ground. Autorotation is a controlled descent in which the helicopter’s rotor blades continue to rotate due to the upward flow of air through the rotor system. This allows the helicopter to descend in a controlled manner without engine power.
So how do helicopters get to the ground when they have an engine failure?
Here’s a step-by-step explanation of how autorotation works and how a helicopter lands during an engine failure:
Recognition of Engine Failure:
When an engine failure occurs, pilots quickly recognize the loss of power through various cues such as a sudden drop in RPM (rotations per minute) and a decrease in engine noise.
Immediate action is essential, and pilots are trained to respond promptly to secure the helicopter and initiate autorotation.
Entering Autorotation:
The pilot lowers the collective control, reducing the pitch angle of the main rotor blades. This minimizes the resistance on the rotor system and allows the blades to continue rotating.
Simultaneously, the pilot applies anti-torque pedal to maintain trim and aft cyclic control to maintain aircraft level attitude. Autorotation requires the helicopter to be in a descending, forward motion, usually around 70 knots or above Vy to generate the necessary airflow through the rotor system and so either an acceleration or deceleration may be required.
Adjusting Rotor RPM:
The pilot adjusts the cyclic and collective control to manage the descent rate maintain a suitable rotor RPM and maneuver the aircraft to a suitable landing spot. Too high a descent rate can result in a hard landing, while too low an RPM may lead to a loss of rotor control.
Flare and Landing:
As the helicopter approaches the ground, the pilot performs a flare, a maneuver initiated by coming aft on the cyclic. This increases the pitch of the rotor blades, slowing the descent rate and reducing the ground speed. The goal is to convert the remaining rotor RPM into lift just before reaching the ground to soften the landing. The helicopter lands with a controlled vertical descent, using the residual energy stored in the rotating rotor blades.
Cushioning the Landing:
Pilots may use additional techniques to cushion the landing, such as pulling collectively just before touchdown to maximize lift and reduce the impact force.
Autorotation is a critical skill taught during helicopter pilot training. It allows pilots to manage emergencies and safely land a helicopter in the event of an engine failure. Although autorotation landings can be challenging, they are a testament to the design and capabilities of helicopters to handle emergencies and provide a controlled descent even without engine power.