As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON DESCENT OILY AIR SMELL IN COCKPIT, BUT NOT NOTICED IN CABIN. TROUBLE SHOT CABIN AIR QUALITY UTILIZING JC 26L00021001, 26L00021003 & FOUND NR 1 ENG DE-OILER SEAL LEAKING. R & R NR 1 ENG OIL BREATHER SEAL ASSEMBLY IAW AMM 72-60-31-001-010-A.