What happened
On June 21, 2004, at approximately 09:30, an Air Tractor AT-802A-AMPHIBIAN, registration EC-IVM, was performing a visual repositioning flight from Enguera Aerodrome to Valencia Airport. The aircraft, operated by Avialsa T-35, S. L., was configured for aerial firefighting operations.
According to the pilot, the aircraft touched down smoothly on its floats. However, as the aircraft decelerated along the runway, intense vibrations were felt, eventually causing the aircraft to come to a stop aligned with the runway centerline. Witnesses observed that the landing gear was in a semi-retracted state, with all four wheels making contact with the ground.
While the initial touchdown caused minimal damage to the reinforced floats, the subsequent towing of the aircraft to a hangar resulted in more significant structural damage, including a broken strut in the float assembly and several deformed skin panels.
The investigation
The CIAIAC examined the aircraft's landing gear mechanism, which is an electro-hydraulic system utilizing two independent pumps. Post-incident testing on jacks demonstrated that the mechanism functioned correctly, with extension times ranging from 36 to 41 seconds, consistent with the flight manual's 35-second specification. The investigation confirmed that the hydraulic actuators and position sensors were intact and that no mechanical failure or inadvertent lever movement caused the gear to retract.
Investigators also examined the cockpit's warning systems. It was determined that the "Amphibian Landing Gear Position Advisory System," which provides audible alerts regarding gear configuration, was non-functional at the time of the accident. Furthermore, the investigation noted that the aircraft's landing gear extension time is notably long compared to other aircraft, requiring high levels of pilot anticipation.
Findings
- The landing gear was in the process of transitioning to the down position at the moment of touchdown.
- The pilot was operating a relatively new addition to the fleet, as previous aircraft used by the operator featured fixed landing gear.
- The absence of the audible landing gear position advisory system deprived the pilot of a critical secondary warning.
- High ambient light conditions can make it difficult to visually distinguish whether the cockpit landing gear lights are illuminated.
- The extended transit time of the landing gear on this specific model requires significant pilot concentration and early configuration during approach.