What was found
ONCE REACHING CRUISE CAPT NOTICED A BURNING SMELL FOR APPROXIMATELY 3 SECONDS, THEN DISSIPATED. ON ARRIVAL SMELL CAME BACK FOR APPROXIMATELY 10 SECONDS, THEN DISSIPATED. INSPECTED NR 1 AND 2 PACKS, LEFT AND RIGHT RELAYS PANELS, NO DEFECTS NOTED AT THIS TIME. RAN APU FOR 10 MINS, RAN BOTH ENGINES FOR 5 MINS, NO DEFECTS NOTED AT THIS TIME. UNABLE TO DUPLICATE THE NOTED DISCREPANCY. OPERATIONS CHECK GOOD. A/C OK FOR SERVICE.