More than two years after five people were killed in a sightseeing helicopter crash in Pigeon Forge in 2016, a newly released report from the National Transportation Safety Board is shedding new light on the crash. 

An NTSB spokesman says it could be weeks or months before a full report is released, but the analysis from the factual report will help to determine a probable cause of the tragedy. 

The helicopter was owned and operated by Great Smoky Mountain Helicopters, Inc. It was purchased in 1986 for air tours and sightseeing. 

Read More: NTSB says Pigeon Forge helicopter rotor blades separated from main wreckage

The day of the crash, another pilot had taken the helicopter out 10 times, while the pilot flying at the time of the crash took an additional five trips out before engine power stopped mid-air.

The fuel in the helicopter was sitting at 300 pounds. Another pilot in the area indicated to investigators he did not hear any distress calls, but did hear a normal landmark position call over Wonderworks by the pilot. 

The helicopter’s engine records show the engine fuel pump, which was overhauled in 2009, when the engine had flown a total of 7,472 hours. The pump had completed 1,078 hours at the time of the accident. According to the manufacturer, an overhaul of the fuel pump wasn’t needed for nearly another 3,000 hours. 

An x-ray of the remaining parts of the aircraft showed no indicator lights were on at the time of the crash. An in-depth look at the engine show nothing in the compressor, combustion section, turbine section and an accessory gearbox, had enough damage to stop the engine from functioning. 

The report indicates the helicopter was grandfathered in and not required to obey FAA Standard 1004 which minimizes fuel spillage near ignition sources in order to increase evacuation time for crew and passengers 

Experts say they had seen wear similar to the wear on the fuel pump drive shaft spline, but not to this extent. They say it is usually caused by a lack of lubricant or corrosion.