Incident Overview
On August 9, 2006, at approximately 12:45 local time, an Air Tractor AT-802A, registration EC-IQC, operated by CEGISA, was damaged during a water landing in the Ría de Pontevedra near the port of Raxo (Pontevedra). The aircraft had departed from Rosinos base (Zamora) at 10:55 local time and landed at Vigo Airport about 50 minutes later. After a 45-minute ground stop, it departed for the Ría de Pontevedra to load water for a firefighting mission.
Approximately 20 minutes after departure from Vigo, the pilot reported that while performing the water-scooping maneuver, he felt a strong deceleration, causing the nose to drop sharply and the propeller to strike the water. The pilot, the sole occupant, was uninjured and evacuated the aircraft without incident.
Aircraft Damage
The aircraft sustained substantial damage including loss of the propeller, damage to the lower engine cowling, and fracture of the forward strut connecting the two floats.
Investigation Findings
No evidence was found of an impact with an underwater object. Inspection revealed no impact marks on the floats. The landing gear was found retracted when the aircraft was recovered from the water. Three extension/retraction cycles were performed successfully.
The fracture of the strut and damage to the cowling appeared to have been caused by the detached propeller.
Landing Gear System
The Air Tractor AT-802A is equipped with two floats allowing water operations and a retractable landing gear with four legs (two per side) housed within the floats. The gear is actuated by two electrically driven hydraulic pumps and four independent actuators. Eight proximity sensors (two per leg) indicate gear position via four blue lights (gear up) or four green lights (gear down). Two red lights indicate the pumps are operating (gear in transit). Extension and retraction order is random, and a full cycle requires approximately 35 seconds.
Analysis
All evidence indicated the aircraft contacted the water with the landing gear extended or partially retracted. This would explain the sudden deceleration and nose-down pitch, leading to propeller contact. The propeller likely detached upon water impact, causing the subsequent damage.
The lighting system for gear position is not especially intuitive, and the green and blue lights may be confused under high brightness conditions. The relatively long gear transit time may contribute to uncertainty about gear position.
The pilot had extensive overall experience and firefighting experience in various land and amphibious aircraft, but not extensive experience specifically in the AT-802A (190 hours on type). The three previous takeoffs and landings that day were on land, and this was the first water operation of the day.
The investigation considered that the most probable cause of the accident was that the aircraft landed on water with the landing gear extended or in transition.