What happened
On December 16, 2016, a DHC-8-Q400 aircraft departed from Cluj-Napoca airport. Approximately one minute after takeoff, the crew received a "Master Warning Doors" alert. The crew continued the climb to flight level 80 (FL80) to determine if the cabin could maintain pressure. Upon confirming that the cabin failed to pressurize, the crew initiated a return to the departure airport.
The investigation
The investigation established that the warning alert occurred at an altitude of approximately 2,950 feet. It was determined that the internal cabin pressure likely forced the doors outward. While the doors were not properly seated in their locks, they remained blocked at their stops. This misalignment created a gap through which air escaped, preventing pressurization.
Following the incident, the doors were opened and correctly closed. A subsequent flight to Warsaw was completed without further issues.
Findings
- The primary cause of the incident was the improper closure of the rear cargo doors.
- The pressure differential between the cabin and the outside atmosphere caused the doors to shift, creating a leak path.