What was found
ELECTRICAL BURNING ODOR FOLLOWED BY SMOKE IN COCKPIT WHICH CAME FROM F/O'S FLOOR SECTION. POWERED AIRCRAFT DOWN IMMEDIATELY. INSPECTED AREA UNDER COCKPIT FLOOR FROM PRESSURE PANEL, INSPECTED F/O'S CIRCUIT BREAKER PANEL RAN BOTH ENGINES AT FLIGHT IDLE FOR 15 MINS. WITH APU GEN ON LINE RT SECONDARY BUSS CYCLED OFF AND ON. SUSPECT PROBLEM WITH APU GENERATING SYSTEM. INSPECTED APU CABLES AT FWD BULKHEAD AND APU CONTACTOR. INSPECTED RELAY PANEL IN COAT CLOSET, F/O'S CB PANEL AND INVERTERS. EVALUATION FLIGHT SATISFACTORY.