What was found
DURING DESCENT THROUGH 5000’ AGL PILOT NOTICED SMOKE COMING FROM UNDERNEATH THE RT SUB PANEL & COULD SMELL BURNING ODOR. TURNED OFF ALL NON-ESSENTIAL ELEC EQUIP & LANDED WITHOUT FURTHER INCIDENT. NO LONGER NOTICED THE ODOR ONCE THROTTLES WERE REDUCED TO IDLE. TROUBLESHOOTING & INSPECTION REVEALED ACM OIL LEVEL TO BE WITHIN LIMITS, GND RUN OPS CHECKS FOUND LIGHT VAPOR ON INITIAL START & CHECK OF THE ACM SYS AT FULL COLD MANUAL MODE. TRANSITIONED TO FULL HOT & IMMEDIATELY VAPOR DISSIPATED, RAN VARIOUS ENGS POWER SETTINGS WHILE IN FULL HOT & NO DEFECTS NOTED. TRANSITIONED BACK TO FULL COLD RAN ENGS AT VARIOUS POWER SETTINGS FOR 15 MINUTES & VERIFIED NO VAPOR OR SMOKE COMING FROM PILOT OR FIRST OFFICER ACM VENTS, COULD NOT DUPLICATE DISCREPANCY.