Air Tractor AT-802A-Amphibian Landing Gear Incident at Valencia Airport (EC-IVM)

Incident Overview and Flight Details On Monday, June 21, 2004, at 09:30 local time, an Air Tractor AT-802A-Amphibian, registration EC-IVM, operated by Avialsa T-35, S. L., was involved in an incident at Valencia Airport. The aircraft, equipped with a Pratt & Whitney Canada PT6-AG67 engine, was conducting a commercial aerial firefighting transfer flight from Enguera Aerodrome to Valencia Airport. The pilot, a 52-year-old commercial pilot with 7,200 total flight hours and 1,400 hours on the type, reported a smooth touchdown on all four wheels. However, while taxiing at low speed, the pilot noted strong vibrations, and the aircraft eventually stopped aligned with the runway centerline. Witnesses observed the landing gear in a semi-retracted position, with all four wheels on the ground. The pilot exited the aircraft unassisted, and there were no fatalities or injuries. ## Aircraft Damage and Maintenance Findings The aircraft sustained minor damage during the landing, primarily limited to friction wear on the reinforced float keels. More significant damage, including a broken float strut and deformation of another strut and several skin panels, likely occurred during the subsequent tow. After the incident, the aircraft was raised on jacks, and the landing gear system was tested. The electro-hydraulic mechanism, powered by two independent pumps, functioned correctly during seven complete cycles and four interrupted cycles. The gear extension time was recorded at 36 to 41 seconds, compared to the manual's 35 seconds. No evidence of system failure was found, and the position sensors for all four wheels were in the correct position. ## Contributing Factors and Safety Analysis The investigation highlighted that the aircraft was the first in the operator's fleet with a retractable landing gear, as most firefighting aircraft typically have fixed gear. The pilot was required to select the gear up for water landings or down for runway landings, with visual confirmation via four green lights for gear down and four blue lights for gear up. The analysis noted that under high luminosity conditions, it can be difficult to distinguish whether a cockpit light is illuminated, and the expectation of seeing a light can lead to a false perception. Additionally, the 'Amphibian Landing Gear Position Advisory System,' which provides acoustic warnings, was not operational at the time of the incident. The prolonged gear extension time, compared to other aircraft, was also noted as a factor requiring special concentration during operations.