As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
INFLIGHT - DURING CLIMB AND HIGH POWER SETTING SMOKE/HAZE IN BOTH CABIN AND COCKPIT. SMOKE/HAZE WOULD ONLY DISSAPATE DURING LOWER POWER SETTINGS. RETURNED TO ORD AND LANDED WITHOUT INCIDENT. REPLACED APU. SYSTEM GROUND CHECKED NORMAL OPERATIONS.