PAYNTON, Sask. -- The Transportation Safety Board says loss of engine power caused an October 2015 helicopter crash that killed two men in west-central Saskatchewan.

The pilot had the Hughes 369D in a low altitude hover while a worker sat on a platform fixed to the chopper attaching a marker ball onto a SaskPower hydro line.

A video shot by another worker on the ground shows flames and smoke coming out of the engine before the helicopter crashed onto a small island in the North Saskatchewan River.

The investigation report says much of the chopper operated by Oceanview Helicopters was destroyed in the fiery crash.

The report says there is an increase risk of injury or death when a single-engine helicopter operates at below speeds and altitudes necessary for a pilot to make an emergency landing.

Following the crash, Oceanview suspended platform work and SaskPower started a helicopter safety program, including better employee training.

"The pilot had to avoid power lines and could not immediately transition into forward flight," said the report released Thursday.

"There was insufficient altitude to conduct a successful autorotation, and the helicopter collided with the terrain."

The report says the helicopter was flying at a speed and altitude that is not prohibited according to its flight manual, but should be avoided.

The safety board notes that some companies restrict how long single-engine helicopters can fly in a prolonged hover.