Actually, helicopters have a built-in mechanical control called the collective pitch lever that allows them to descend slowly and land even if the engine dies. This maneuver is called autorotation. Destin Sandlin from SmarterEveryDay has a great new video (below) that explains how it works.

If a helicopter runs out of fuel or the engine fails, it does not "fall like a brick." Instead, a life-saving maneuver called autorotation kicks in. As the engine stops providing power, a mechanical clutch (the freewheeling unit) automatically disengages the main rotor from the engine, allowing the blades to spin freely. The pilot must immediately lower the "collective" lever to reduce drag, allowing the helicopter to glide downward. This descent causes air to flow upward through the rotor blades, which keeps them spinning fast enough to maintain control and provide lift. Just before hitting the ground, the pilot "flares" the helicopter (pulling the nose up) to slow down and then uses the remaining kinetic energy in the blades to "cushion" the landing. It is a standard emergency procedure that all helicopter pilots must master during training; while it requires precision and quick reflexes, it allows for a safe, controlled touchdown even without any engine power.

Running out of fuel in a helicopter can have serious consequences, but the exact outcome depends on several factors, including the type of helicopter, the altitude at which the fuel runs out, and the pilot’s skill and reaction time. Here’s what typically happens:

1. Engine Failure:

• When the fuel runs out, the helicopter’s engine(s) will stop producing power. This means the main rotor will no longer be driven by the engine.

2. Autorotation:

• In most helicopters, the pilot can perform an autorotation maneuver to safely land the aircraft without engine power. Autorotation involves using the helicopter’s descending motion to keep the rotor spinning, generating lift and allowing for a controlled descent and landing.
• The pilot must reduce collective pitch to maintain rotor RPM and glide the helicopter toward a suitable landing area.

3. Controlled Landing:

• If the pilot successfully executes autorotation, the helicopter can make a controlled landing, often with minimal damage. However, the landing may still be rough depending on the terrain and the pilot’s skill.

4. Crash:

• If the pilot fails to perform autorotation correctly, or if there isn’t enough altitude or time to execute the maneuver, the helicopter could crash. This could result in significant damage to the aircraft and potential injury or fatalities for those on board.

5. Altitude Matters:

• Higher altitudes give the pilot more time to react and perform autorotation, increasing the chances of a safe landing. Running out of fuel at low altitude leaves little time for recovery.

6. Prevention:

• Modern helicopters are equipped with fuel gauges and warning systems to alert pilots of low fuel levels. Pilots are trained to monitor fuel consumption and plan for refueling well before fuel runs out.

Summary:

Running out of fuel in a helicopter is a critical emergency, but with proper training and quick action, a pilot can often execute an autorotation and land safely. However, the situation is highly dangerous and underscores the importance of careful fuel management and planning.