What was found
(CAN) DURING CLIMB OUT, AN OILY SMELL WAS DETECTED IN BUSINESS CLASS SECTION OF PASSENGER COMPARTMENT. SMELL DISSIPATED AFTER LEFT HAND AIR CONDTIONER PACK TURNED OFF. MAINTENANCE CHECK REVEALED AUXILIARY POWER UNIT WAS CONTAMINATING LEFT AIR CONDITIONER PACK. AUXILIARY POWER UNIT REPLACED AND OPERATIONAL CHECK CARRIED OUT, SERVICEABLE.