What was found
NAS - FLT 5365 - DURING PREFLIGHT INSPECTION, THE FLIGHT ATTENDANT REPORTED A BURNING ELECTRICAL SMELL ON THE AIRCRAFT. THE CAPTAIN WENT TO THE COCKPIT AND NOTICED THE ODOR WAS VERY STRONG AND ALSO NOTICED A HAZE IN THE AIR. THE CAPTAIN TURNED ALL POWER OFF AND DISCONNECTED THE GROUND POWER UNIT. NO OTHER INCIDENTS REPORTED. MAINTENANCE REMOVED AND REPLACED BOTH RECIRCULATIONS FANS IAW ATR MM. OPERATIONAL CHECK WAS GOOD AND AIRCRAFT WAS RETURNED TO SERVICE.(M)