The helicopter, which was on a routine supply mission and had just departed a nearby base, was reportedly shot down by Taliban ground fire.
The pilots were able to successfully land the aircraft in an open field and everyone got out with only minor injuries.
Investigators say an in-flight fire ultimately brought down the chopper.
They were reluctant to render a finding that the aircraft was shot down, saying there was "no conclusive correlation" between the gunfire and the blaze.
The investigation into the August 2010 crash looked only at the effectiveness of life support equipment and emergency procedures for getting out of the aircraft.
The recommendations, including better seating and restraints, are something that air force planners will have to consider as the military prepares to take delivery of 15 brand new CH-147-F helicopters next year.
The Air Force Directorate of Flight Safety also noted that it was the first time in almost 40 years that it investigated a case where an aircraft has been brought down by enemy fire.
The last time that happened was when a C-115 Buffalo was brought down over Syria in August 1974, killing nine Canadians.
Officials say they do not normally investigate losses due to enemy action and suggest such skill sets need to be developed.Suggest a correction