As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE AIRCRAFT WAS IN FOR HEAVY CHECK, LEVEL 2 CORROSION WAS FOUND AT THE LAV SERVICE DOOR HINGE ATTACH POINT ON FUSELAGE. FROM FUSELAGE STATION X1.000 TO X18.250. MAINTENANCE REMOVED AND REPLACED DOUBLER P/N 85307789-101 IAW BOMBARDIER Q400 DWG 85307796 AND Q400 SRM 42-05. AIRCRAFT IS CURRENTLY STILL OUT OF SERVICE FOR HEAVY CHECK COMPLETION.