Weight issues may have been a factor in the California helicopter crash last year that claimed nine people, including seven wildland firefighters, according to a preliminary report released by NTSB.
The helicopter had just lifted off to transport firefighters to a new location when the main rotor developed problems. Within minutes, witnesses saw it crash.
Four people on board managed to escape before the Sikorsky S-61N burst into flames.
Of those who perished on the California hillside were seven wildland firefighters from Oregon, the pilot and a forestry official.
The NTSB report released includes conversations between the pilot and co-pilot as the chopper starts to take off.
The final report will be issued later.
