Brian

Former Army Helicopter pilot here. Listening to the audio from the inside of the helicopter was chilling and terrifying. The audio clearly and unmistakenly picks up the ambient sounds, including the turbine engine high pitched sounds, the sudden increase in that same sound, the warning beeps and audible alarms, followed by the pilot executing the standard emergency procedure for either tail rotor malfunction or engine failure. What I heard is this: the sudden rise in the tone of the humming turbine, suggests that the engine did NOT fail. Nope. If the engine failed, the hum of the turbine would have gone quiet. If it was loss of fuel, it would have just gone silent. If it was a mechanical, like turbine blade failure, transmission failure, then there would have been a loud bang. Neither of those things happened. Instead, I heard the engine spin up even higher, then the warning beeps, followed by the alarm. That sure sounded like an overspeed warning followed by an overspeed governor shutting down the engine fuel supply, likely to protect from overspeed and slinging of the blades. What would cause the sudden increase in engine noise? Easy: at a hover, the pilot is pulling near maximum power, and the blades are at near full pitch. Everything is damn near maxed out. The higher pitch that suddenly came on, was from the rotor blades or tail rotor suddenly having LESS of a load, while the pilot had nearly full collective pitch raised. The loss of the load, would cause the engine to overspeed. So, what would decrease the load? Two things: tail rotor drive shaft failure, or tail rotor (or its components failure), OR failure of engine drive train components to the main rotor. Since the engine is creating power to the main rotor or the tail rotor, then losing one (or both) of those engine loads would cause the engine to overspeed from too much power being supplied for less of a load. What I heard was engine humming overspeed, with a warning beep, then steady alarm, then the pilot reacting to engine failure. The emergency procedure for engine failure is “Collective pitch down, throttle off, land, fuel valve handle off, battery off.” If it was a tail rotor failure, which it was not, then the video would have shown the helicopter spinning rapidly to the left, counterclockwise, from the sudden loss of tail rotor force. But the video shows the helicopter stayed pointing in the same direction, no yawing, no spinning. So, the mechanical connection between the engine and main rotor likely failed, causing the engine to overspeed, followed by alarms, and the pilot executing the emergency procedure. He was on the wrong side of the dead man’s’ curve, on the performance charts. He was at too high of main rotor pitch, not enough altitude, not enough airspeed, to maintain rotor speed, thus leaving him not enough rotor rpm to execute a safe autorotation deceleration or cushioning from full collective just before landing. He hit hard, the the helicopter collapsed downward mechanically, the fuel lines ruptured and caught fire because the engine was still running, engulfing the helicopter in flames. Unsurvivable impact. Truly tragic. But, this scenario is taught to every helicopter pilot, every one trains on autorotations, but NOT on the wrong side of the dead man’s curve, because engine failure or drive train failure at that point is not survivable. Every pilot knows the risks, and tries to avoid being in that zone. But, the news reporters want the shot, so they get into a high out of ground effect hover, too close the ground, and play with death every time they do that. Sad, but avoidable if the pilot was hovering at a higher altitude.