ELBA, N.Y. — The National Transportation Safety Board released its preliminary report Tuesday on the deadly Mercy Flight helicopter crash on April 26 in Genesee County. 

The helicopter went down near the town of Elba, off of Norton Road, about halfway between Buffalo and Rochester.

Pilot James Sauer, 60, of Churchville, a retired New York State Police pilot and former Rochester Police officer, and Stewart Dietrick, 60, of Prosper, Texas, a flight instructor, died in the crash.

According to the preliminary report, a representative of Mercy Flight Inc., said that the crash took place during the second instructional flight of the day, with multiple flight reviews planned throughout the day.

The NTSB report says Dietrick was conducting a flight review on behalf of the manufacturer, Bell Helicopter.

While the report provided few clues as to what caused the Bell 429 helicopter to crash, it did say a section of the tail boom and tail rotor shaft showed evidence it may have come into contact with the helicopter's main rotor blade.

The same day of the crash, the FAA released an official document on the Bell 429, warning owners of an issue with the tail rotor.

The preliminary report states that several witnesses saw and heard the helicopter flying overhead before the crash. One witness said that he saw that the helicopter was “almost stationary” after it flew over, and then as it began flying away, he heard a loud “bang,” and the helicopter began to descend out of control.

The report says that an additional witness said the helicopter was hovering before it “fell apart” with the fuselage falling separately.

Another witness reported that they heard what sounded like a “whoosing” sound coming from the engine, and then heard “three loud and rapid cracks,” according to the report, before hearing the helicopter impact the ground and the rotor blades hitting the ground rapidly.

The NTSB report says that the helicopter fuselage containing the cockpit, engine, transmission and rotor assembly struck electrical distribution wires while impacting the terrain at about 1,220 ft. The helicopter then came to a rest of its left side and a small fire started that had started post-crash was quickly extinguished by first responders, the report says.

NTSB investigators say the official cause of the crash may not be known until spring 2023.

The full preliminary report can be read below: