As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKY & OILY SMELL COMING FROM ENVIRONMENTAL SYS. SMELL OCCURS WITH BOTH COCKPIT & OR CABIN PACS. NO VISIBLE SMOKE IS OBSERVED. REMOVED & REPLACED APU WITH CUSTOMER SUPPLIED UNIT. DONE IN REF WITH CE-750 MM CH 49-10-00. OPS & LEAK CHECKS GOOD. ALL ACCESS CLOSED.