As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING DESCENT FROM FL430, SMELLED SMOKE DURING POWER REDUCTION. ODOR TOOK PLACE EVERY TIME POWER WAS REDUCED. FOUND OIL RESIDUE TO LT WATER SEPARATOR DOME. CHECKED DUCTING IN BLEED AIR SYSTEM BETWEEN LT ENGINE AND COCKPIT ACM, NO OIL RESIDUE NOTED. REINSTALLED REMOVED BLEED AIR DUCTING. REMOVED AFT COCKPIT ACM. INSTALLED REPAIRED ACM IAW CMM 21-00-00 OPS & LEAK CHECKED GOOD. WORK DONE IAW MM 21-51-00.