As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AFTER START WHEN NR 2 ENGINE BLEED WAS SELECTED ON, SMOKE WAS GENERATED IN THE CABIN. INSPECTION FOUND GROOVES IN THE P2.5/03 SWITCHING VALVE AND VALVE COVER. THE PARTS WERE REPLACED. THE ENGINE GROUND RUN SERVICEABLE AND THE AIR QUALITY WAS RESTORED.