What happened
On January 9, 2018, a flight crew consisting of a pilot and an instructor, operating on behalf of the Warsaw Aero Club, was conducting a flight from EPBC to EPGY. While descending from 4,000 feet at approximately 10 nautical miles from EPGY, the aircraft reached a speed of about 100 knots when the right-hand door began to open from the hinge side. The upper portion of the door displaced approximately 7cm away from the airframe pillar.
Upon realizing the door was not secure, the crew decided to terminate the flight and return to the departure aerodrome, EPBC. To prevent further movement of the door, the crew secured it using a shoulder strap and reduced the aircraft's airspeed. The subsequent landing at EPBC was completed without further incident.
The investigation
The investigation, conducted by the aircraft operator, focused on the structural integrity of the door latching mechanism. The examination revealed that the failure originated from a structural defect within the door assembly itself.
Findings
- The primary cause of the incident was a crack in the door reinforcement located in the middle front section of the door.
- This crack prevented the upper front part of the latching frame from engaging and locking correctly.
- The crack was not visible during routine pre-flight inspections because it was obscured by the interior door upholstery.