What happened
On November 12, 2002, a Lockheed L1011-500, registration CS-TMX, operated by Yes Air, arrived at Lisbon Airport following a flight from Cancun, Mexico. During the night, the aircraft had departed from Puerto Plata, Dominican Republic. The flight crew did not report any in-flight anomalies or unusual vibrations during the journey.
Upon arrival at the designated stand at approximately 11:05 UTC, an airport supervisor conducted a routine inspection and discovered that a small access panel located on the lower right side of the tail cone was missing. This specific panel provides access to the horizontal stabilizer actuators. A subsequent inspection of the runway was performed, but the panel and any detached fragments were not recovered.
The investigation
The GPIAAF investigation focused on the maintenance history of the aircraft. It was established that the aircraft had recently undergone C2 and A9 heavy maintenance checks at GAMCO in the United Arab Emirates between September 18 and November 1, 2002. The maintenance protocol for these checks specifically required the opening of access panels to inspect the horizontal stabilizer actuators, including the panel in question.
Upon the aircraft's arrival in Lisbon, it was moved to TAP facilities for corrective maintenance. During this inspection, investigators found that the hinges used to secure the access panel to the airframe were fractured. The panel is designed to be fixed to the structure via two hinges and held closed by securing screws.
Findings
- The aircraft had recently undergone extensive maintenance involving the opening of the tail cone access area.
- The inspection of the aircraft structure revealed that the hinges of the access panel were fractured.
- The primary cause of the incident was the improper installation or omission of the securing screws intended to hold the panel to the fuselage.
- It is concluded that the failure to properly secure the fasteners allowed the panel to separate from the hinges, likely during the final flight leg from Cancun to Lisbon.