A Bell Helicopter 525 Relentless test aircraft broke up in mid-air, the National Transportation Safety Board said a couple weeks after the July crash that killed two test pilots.
Although the final investigation report is still pending, preliminary findings of the July 6 crash showed that the main rotor struck the front and back of the helicopter when it was traveling 199 knots at an altitude of 1,975 feet.
NTSB spokesman Peter Knudson.
“The signatures indicate that the main rotor struck both the tailboom and the nose,” said NTSB spokesman Peter Knudson in July. “The probable cause of the inflight break-up is still under investigation.”
Here is the article with the initial findings of the NTSB.