A preliminary report says a sightseeing helicopter spun at least twice before crashing in the Grand Canyon, killing three British tourists and injuring three others and the pilot.
The National Transportation Safety Board doesn't say what caused the Feb. 10 crash, but aviation expert Jerry Kidrick says the report's description of the helicopter's movements indicates its tail rotor wasn't working properly to keep the helicopter from spinning.
Kidrick, a former U.S. Army pilot who teaches at Embry-Riddle Aeronautical University, says that could be due to a mechanical problem or wind conditions in the canyon.
The helicopter crashed in a rocky wash while approaching landing pads on tribal land outside Grand Canyon National Park.
A full NTSB report won't be done for more than a year.