Engine failure appears to be the primary culprit in the crash last month near Tullahoma Airport of an aircraft carrying 20 passengers on a skydiving excursion, a crash that left five seriously injured after the plane hit trees as the pilot tried to make an emergency landing.

The pilot’s statement about engine failure is part of the NTSB (National Transportation Safety Board) preliminary investigative report about the June 8 crash which saw the Dehavilland DHC-6 Twin Otter narrowly miss the Beechcraft Heritage Museum as it hit trees and the ground while the pilot tried to make it back to the runway from where they had just taken off.

The preliminary report revealed that the commercial pilot and five passengers were seriously injured, and 15 passengers were not injured in the crash. The flight, investigators said, was being conducted as a 14 Code of Federal Regulations Part 91 skydiving flight. The pilot was attempting to take off from runway 24 at the Tullahoma Regional Airport (THA), Tullahoma. The noon-time excursion was his fourth flight in the airplane that day.

“The pilot stated the takeoff was normal and he raised the flaps once the airplane was clear of obstacles,” the NTSB reported. “When the airplane was about 500 feet above the ground, the pilot noticed asymmetrical thrust on the engines while syncing the propellers. He said, ‘In the following seconds, I continued trying to sync the props and was getting unusual feedback in the controls. I didn’t notice any loss of power in the gauges, but something felt a miss.’ The pilot lowered the nose of the airplane and saw the altitude level off, and airspeed decrease.”

 At that point NTSB investigators said the pilot determined that the left engine had lost power.

“He initiated ‘engine out procedures’ and turned left, back to the airport to try and land on runway 36,” the report revealed. “The pilot could not remember if he secured the left engine; however, he did remember adding flaps as per the engine-out procedures. The pilot said he tried to maintain airspeed above the single-engine minimum control speed (Vmc), but the airplane continued to descend.”

The report noted that the aircraft was not able to maintain altitude to get back to the runway to make a safe land.

“The pilot was unable to make it back to the airport and chose to land in a field,” the NTSB said. “There were two trees in the field that he was unable to avoid, and the airplane impacted the trees. The airplane came to rest upright, but the left wing, left engine and the tail section separated from the airframe, resulting in substantial damage. The right wing and engine remained secured to the airframe. There was no post impact fire.”

The preliminary report includes evidence that has been uncovered by investigators. The final report with findings may not be ready for several months and can sometimes take over a year.