What was found
DURING DESCENT, STRONG SMOKE ODOR DETECTED AFTER REDUCING POWER, UNABLE TO DETERMINE CAUSE OR ISOLATE SOURCE. AFTER 3-4 MINUTES THE ODOR WENT AWAY. CHECKED NR 1 AND NR 2 ENGINE OIL LEVELS AND BOTH ACM OIL LEVELS, ALL LEVELS AT FULL. RAN BOTH ACM’S WITH APU AND BLEED AIR AND ENGINE BLEED AIR, NO ODORS NOTED, UNABLE TO DUPLICATE DISCREPANCY ON GROUND, MAINTENANCE PERFORMED IAW STANDARD PRACTICES.