(from the article) .... The No. 1 525 prototype’s main rotor blades appear to have struck its tail and nose during a high-speed, engine-out test that ended with the July 6 crash that killed its two pilots, Rotor & Wing International has learned.

“We saw signs consistent with a blade strike on the tailboom,” the National Transportation Safety Board’s investigator-in-charge for the probe, John Lovell, told R&WI, adding that investigators also believe “the nose was struck.”

The fly-by-wire Bell Helicopter super-medium, twin-engine helicopter broke up in midair during a flight to expand its operating envelope that included a test of the 525’s performance in one-engine-inoperative conditions as the aircraft approached its never-exceed speed (Vne), Lovell said. Bell early last March said it had flown the 525 above 200 kt in a shallow dive. A flight tracking service, Flightradar24, had reported July 6 that its last data set on the 525 flight put the aircraft at 199 kt at 1,975 ft.

Prior to the breakup, Lovell said, “data indicates that main rotor rpm dropped significantly.” He also said some of the aircraft’s main rotor blades “appeared to have dropped from their normal plane” of rotation.

Test pilots in a Bell 429 chase aircraft reported that some of the main rotor blades were moving out of plane before the aircraft broke up over Italy, Texas, about 30 nm south-southwest of the flight’s launch point, Bell’s Xworx research center at Arlington Municipal Airport.

The data also contains indications of significant vibration in the main rotor during the accident sequence, Lovell said. Investigators are working to identify when that vibration began and its cause.

http://www.aviationtoday.com/rw/persona ... 5bLiaLWRVc

Seen the results --- burn marks on the tail no strike marks, looks like a tail boom failure and a tuck.....