Event Summary
On December 16, 2016, approximately one minute after takeoff from Cluj-Napoca Airport, the crew of a DHC-8-Q400 received a “Master Warning Doors” alert. The aircraft continued climbing to flight level 80 (FL80) to assess pressurization. After determining that the cabin was not pressurizing, the crew decided to return to the departure airport.
Investigation
The investigation revealed that the Master Warning Doors indication appeared at an altitude of approximately 2,950 feet. The pressure inside the fuselage likely pushed the rear cargo door outward. The door had not been correctly seated on its latches but was blocked on the stops, creating a gap through which air escaped. After opening and properly closing the door, the issue did not recur upon the second takeoff. The subsequent flight to Warsaw proceeded without any interruptions.
Cause
The cause of the incident was determined to be improper closing (not fully closed) of the rear cargo door.
Preventive Actions
The operator recorded the event in its Safety Management System (SMS) database and classified it according to established criteria. As a corrective measure, it was recommended to consider conducting a handling inspection at Cluj-Napoca Airport by the operator's ground handling services. No safety recommendations were issued by the investigating commission.