What was found
HEAVY GREY SMOKE FILLED THE CABIN WHILE APU OPERATING DURING PREFLIGHT. LINE SERVICE INITIALLY ALERTED ME OF SMOKE COMING OUT OF APU EXHAUST & THEN SECONDS LATER THE CABIN & COCKPIT FILLED WITH SMOKE.
As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
HEAVY GREY SMOKE FILLED THE CABIN WHILE APU OPERATING DURING PREFLIGHT. LINE SERVICE INITIALLY ALERTED ME OF SMOKE COMING OUT OF APU EXHAUST & THEN SECONDS LATER THE CABIN & COCKPIT FILLED WITH SMOKE.