Incident Overview
On 23 January 2016, a Boeing 777-300 aircraft landed at Warsaw Chopin Airport (EPWA) for refueling. A ground crew was assigned, consisting of a self-propelled stair vehicle and a towed vehicle. Due to technical reasons, refueling could only be performed from the left side of the aircraft while passengers remained on board, so the stairs were positioned on the right side.
Sequence of Events
After refueling was completed and the coordinating ground worker informed the stair operator, the operator checked that the aircraft door was closed, lowered the stabilizer feet, and began slowly reversing the stair vehicle. Shortly after, the operator felt a jolt, stopped the vehicle, and exited to inspect. The stair's curtain (a soft roof component) had become caught on an open door. The stairs were repositioned against the aircraft door.
Damage and Consequences
Mechanics inspected the door and found that the upper edge of the door strip had been bent over a length of approximately 70 centimeters due to the curtain catching on the door. After consulting with the airline's operations center, the flight was canceled.
Investigation Findings
The stair operator was tested for alcohol immediately after the incident and showed no alcohol in exhaled air. The operator held all required qualifications for ground handling duties. The self-propelled stairs were serviceable at the time and had undergone periodic technical inspections per manufacturer requirements. Analysis of procedures and instructions for operating the stairs found no evidence that they contributed to the incident. Two on-site inspections and tests ruled out the possibility of door damage by the stair curtain when the door is closed.
A request was made to the airline for a report or note from the cabin crew who had operated the affected door, but no response was received.
Probable Cause
The most likely cause of the damage to the aircraft door was its opening at the moment when the stabilizing feet of the self-propelled stairs were being lowered by the operator.