As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON GROUND WITH GPU POWERING ACFT & AIR CONDITIONER RUNNING, LARGE AMOUNTS OF SMOKE CAME FROM VENTS UNDERNEATH THE AFT CARGO COMPARTMENT. REMOVED AND REPLACED MOTOR ASSEMBLY. RESERVICED SYSTEM. RAN A/C UNIT FOR 30 MINUTES. OPS CHECKED GOOD IAW CMM 21-00-07 AND MM 21-52-00.