The helicopter crash that killed country singer Troy Gentry was caused by a faulty engine.

According to a preliminary report the National Transportation Safety Board released Wednesday , pilot James Evan Robinson said that “he was unable to control engine RPM with throttle inputs” when he radioed for help, adding, “He reported he could ‘roll’ the twist-grip, but that there was no corresponding change in engine rpm when he did so.”

The pilot elected to stop the engine and perform an autorotation, which he had done in the past. The main rotor is supposed to turn — even without power — which essentially glides the chopper to the ground. According to the NTSB, the pilot was told to autorotate the aircraft over the runway.

The pilot started the autorotation 950 feet above the ground. The RPM “decayed” to the point where the pilot could see the individual rotor blades. It then fell to the ground. A high-pitched whine was heard as it crashed.

The pilot initially tried hovering until emergency vehicles arrived below him, but the situation got desperate enough that he turned off the engine and attempted an autorotation to the ground.

The NTSB says Gentry was on the chopper purely for pleasure.

A public celebration of life with be live-streamed from the Grand Ole Opry today. at 11AM CT.