What was found
AN ELECTRICAL BURNING ODOR OBSERVED IN THE COCKPIT & CABIN NEAR SEAT ROW 4, DECLARED EMERGENCY, LANDED WITHOUT FURTHER DIFFICULTIES. MX REMOVED AFT WALL OF FWD BAG PIT & INSPECTED RECIRCULATION FANS & DUCTING FOR EVIDENCE OF OVERHEATING & ODOR, NO DEFECTS NOTED. DUE TO FAILURE HISTORY: REPLACED AVIONICS COOLING FAN (18HQ) IAW AMM 21-26-51-401, OPERATIONAL CHECK WAS GOOD. FUNCTIONAL CHECK OF AVIONICS COOLING FAN CONFIRMED FAILURE, BEARING NOISE COULD BE HEARD DURING TEST. R & R WORN BEARINGS & BALANCED ROTOR & MOTOR IMPELLER IAW CMM. RE-TEST OF UNIT GOOD.