What happened
On March 4, 2007, an Airbus A319, registration CS-TTO, operated by TAP Portugal, arrived at Lisbon Airport from Paris. Because the aircraft was parked at a stand without a jet bridge, motorized passenger stairs were utilized for disembarkation.
As the first passengers began to exit the aircraft through the forward left door, the motorized stairs suddenly shifted. The upper platform slid downward by approximately 0.5 meters and moved horizontally away from the aircraft fuselage by about 1 meter. During this movement, a 59-year-old passenger, who was distracted while assisting family members, failed to find footing on the platform. The passenger fell through the newly created gap from a height of approximately 2.9 meters, striking the ground with his head. The passenger suffered a traumatic brain injury and lost consciousness, requiring emergency medical evacuation via ambulance.
Following the incident, the crew immediately suspended disembarkation through the forward door and diverted all remaining passengers to the rear exit.
The investigation
The GPIAAF investigation focused on the mechanical integrity of the motorized stairs, manufactured by FMC EAE. Technical examinations of the equipment revealed significant structural issues, including old fractures and widespread corrosion on the rear support linkages of the fixed step section.
Investigators found that the right-side support linkage had failed due to a lack of lubrication, which caused the joint to seize. This seizure subjected the structural components to extreme torsion and shear forces, eventually leading to the fracture. On the left side, the support tube had also fractured near the weld points due to continuous stress from the lack of a functional support structure.
Findings
- The primary cause of the accident was the fracture of the rear support linkages on the lower section of the stairs, which caused the platform to slide away from the aircraft.
- A critical lack of lubrication in the moving joints led to the seizure of the mechanism, creating the high-stress conditions that caused the metal to fail.
- The manufacturer's maintenance program was insufficient, as it failed to specify the need for lubricating these specific joints and lacked dedicated points for lubricant application.
- The operator's maintenance program did not include specific instructions for the lubrication of these structural hinges.
- There was an absence of thorough pre-use visual inspections to detect the existing corrosion and structural fatigue in the equipment.