As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON GROUND BURNING OIL SMELL WHEN PACKS ON APU. APU BLEED AIR MODULATING VALVE. REMOVED AND REPLACED BOTH WATER SEPERATORS FOR AIR CONDITIONING. APU COMPARTMENT INSPECTED. NO OIL LEAK. REACTIVATED APU BLEED AIR VALVE AND PERFORMED APU RUN, CHECKED NO OIL SMELL IAW AMM 21-54-01. OK FOR SERVICE.