As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING DESCENT WITH POWER REDUCED TO APPROX 75-80 PERCENT N1 A PUFF OF SMOKE COME FROM BOTH OF THE COCKPIT WEMACS BELOW THE GLARESHIELD FOLLOWED BY VERY STRONG SULFUR ODOR. TROUBLESHOT DISCREPANCY TO A FAILED COCKPIT ACM. REMOVED AND REPLACED ACM IAW 750 MM CHAPTER 21-50-01 OPS CHECK GOOD.