A simple Hover Power Check should have prevented this accident as would have using the British style Confined Area Takeoff technique of ascending to the necessary height to clear your barriers THEN translating forward. The Crew being US Army trained and checked by FAA/USFS pilots whose organizations use the same techniques as do the US Military (thinking US Army) actually, uses a different technique of a forward acceleration climbing to clear the barriers by the same safe margin the British do.....the difference is using the British method allows you to discover you do not have the necessary power while still over your takeoff point. As this was from a ridge line with some trees in the takeoff path despite the ground steeply dropping away.
The LZ was dusty, and had been watered down between the first and last flights, which may have played a role in the decision not to do the Hover Check first.
A Torque split with both engines at Topping would normally produce a Split in Torque indications as previously noted by others. As the CVR transcript did not mention any comment about a split and the CVR analysis did not mention any decrease in Engine or Transmission sounds that would indicate any kind of engine malfunction that would have resulted in Tonal or Frequency changes, we have to assume the Engines were operating normally as did the NTSB.