What happened
On 15 April 2010, a Tecnam P2002-JF, registration EI-WAT, was conducting a private cross-country flight from Waterford Airport to Inis Mór Airfield in the Aran Islands. Following a successful landing on Runway 14, the pilot began decelerating to taxi speed. As the aircraft approached the runway turn-off, the pilot noticed a slight downward tilt toward the port side.
Believing the aircraft might have suffered a tire puncture, the pilot continued taxiing to clear the runway. However, as the aircraft turned onto the taxiway, the port wing dropped rapidly accompanied by a loud mechanical sound. The pilot immediately stopped the aircraft and shut down the engine. There were no injuries to the pilot or the single passenger, though the aircraft sustained minor damage.
The investigation
Investigators from the AAIU examined the aircraft and the surrounding area. They recovered a missing self-locking nut on Runway 14, approximately 50 meters before the taxiway turn-off. Additionally, a washer and a spacer from the main landing gear were found on the taxi and near the aircraft's final position.
Technical analysis revealed that the inboard end of the left landing gear strut had slipped off its securing bolt, which subsequently punctured the aircraft's lower skin. The investigation also identified an unauthorized 14 mm hole drilled into the aircraft's inner lower skin, likely during the manufacturing process. This extra hole overlapped the area of the retaining bolt.
Findings
- The primary cause of the incident was the separation of a self-locking nut from its bolt, which allowed the port landing gear to partially collapse.
- The nut likely loosened and fell off the bolt during the landing roll, causing the initial downward tilt felt by the pilot.
- The presence of an extra hole in the aircraft skin may have caused the spacer to flex, contributing to the loss of tension in the bolt and nut threads.
- Standard visual inspections, performed through a small inspection hole, were unable to detect the gradual loosening of the hardware.
- The self-locking nut alone provided an insufficient locking mechanism for this critical load-bearing component.
Safety action
Following the investigation, two safety recommendations were issued to the manufacturer, Costruzioni Aeronautiche Tecnam s.r.l.:
- The implementation of a more robust locking arrangement for the inboard end of the landing gear struts.
- A review of manufacturing quality control procedures to prevent defects such as extraneous drilled holes in the aircraft skin.