As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STRONG SULFUR ACID ODOR WITH NO SMOKE PRESENT WAS OBSERVED IN COCKPIT ONLY. OCCURRED DURING INITIAL DESCENT FROM CRUISE ALTITUDE AND BECAME STRONGER AGAIN IN LANDING PHASE. FOUND TURBIN ON 'PAC' STIFF TO TURN BY HAND & WILL NOT RUN WITH 'PAC' IN NORM OR HIGH REMOVED FWD AND AFT EXHAUST DUCTS TO GAIN ACCESS. REMOVED AND REPLACED AFT ACM IAW CE 750 M.M. CHAP. 21-50-00. UNIT OPERATIONALLY & LEAK CHECKS GOOD.