What was found
DURING CLIMB OUT, THROUGH 8000 FT, THE FLIGHT ATTENDANTS REPORTED A STONG ODOR OF BURNED RUBBER. SOME REPORTED A SLIGHT HAZE. RETURNED TO DEPARTURE, AN EMERGENCY WAS DECLARED. LANDED WITHOUT INCIDENT. THE AIRCRAFT WAS REMOVED FROM SERVICE. FOUND THE RIGHT RECIRCULATION FAN TRIPPING THE CIRCUIT BREAKER AND CAUSING AN ACRID, BURNING RUBBER ODOR. REPLACED THE RECIRCULATION FAN IAW 21-25-02 AND FILTERS IAW 21-25-01. AIRCRAFT WAS GROUNDED.