As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LOWER DOOR NOT SHUT ILLUMINATED IN FLIGHT AT APPROX 9000 FT. STAYED ON FOR DURATION OF FLIGHT. AIR RETURN. MAINTENANCE REMOVED AND REPLACED REAR CARGO DOOR IAW AMM 52-31-21 201/202 ALL CHECKS GOOD. PN ON/OFF HS523J019-006 SN ON HAF/DH-0118 SN OFF HAF/DH-157.