As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
OILY SMELL IN COCKPIT AND CABIN SMELL IS STRONGER WHEN THE APU IS RUNNING. INSPECTED APU AND FOUND STARTER/GEN PAD SEAL LEAKING. REPLACED WATER COALESCER SOCK. RAN BOTH ENGINES AND NO ODOR NOTED. APU DEFERRED IN ACCORDANCE WITH CE560XLS MEL. COMPLIED WITH MEL MAINTENANCE PROCEDURES. PULLED AND COLLARED APU MASTER C/B.