Occurrence
On May 31, 2021, just before 06:00 UTC, an aerial agricultural work team consisting of two pilots, two human flaggers, and two field workers began rice seeding on a farm near Virtudes, Azambuja, Portugal. The aircraft, a Piper PA36-285 registered CS-DDL, was used for the mission. The team performed eight initial flights, each with several swath passes, until the first pilot was relieved by his colleague for another series of eight scheduled flights.
For the mission, the aircraft was prepared with a standard big bag weighing 500 kg of dry rice seed, estimated at around 650 kg considering actual moisture conditions. After taking off from a nearby agricultural airstrip, the pilot headed to the rice field seeking visual references from the flaggers. Unable to see the first flagger due to nearby vegetation, no seed was dropped on the first northwest pass. After a 180° left turn, the pilot lined up southeast over the second flagger and initiated a partial drop covering 30 to 40 meters, as radio communication indicated the swath was not over the intended location.
The pilot then began another turn with a right exit followed by a left 180° turn to align with the first flagger. During this left turn, when nearly aligned northwest, the pilot received radio information that he was overshooting to the right and would not be able to line up on the intended spot. The pilot reported feeling the aircraft sink, leading him to apply maximum power as he sensed engine power loss. He heard the stall buzzer, attempted to level the wings and lower the nose to gain airspeed, and was aware of nearby power lines. The aircraft assumed a left-wing and nose-down attitude (>60°) with no possibility of recovery, colliding with the ground without the pilot having time to release the seed load.
Injuries and Damage
The initial ground impact involved the left-wing tip and leading edge, followed by the engine, hopper, and main gear, all separating from the fuselage. The right wing leading edge then struck. The aircraft rotated about its vertical axis, pivoting on the tail wheel, elevators, and rudder, before coming to rest inverted. The cockpit remained intact despite forward fuselage destruction; the pilot sustained minor injuries from the seat belts and was able to exit the wreckage unaided. He was transported to Vila Franca de Xira hospital as a precaution and discharged hours later. The aircraft was destroyed. All flight control surfaces were identified, and their continuity was confirmed. No evidence of in-flight structural failure was found. All components forward of the firewall were detached due to collision forces. No relevant pre-existing faults were identified. The propeller damage was consistent with the engine producing power at impact.
Investigation
The GPIAAF (Portuguese Aviation Safety Authority) was notified at 08:19 UTC and deployed investigators. The accident occurred during daylight with clear skies, calm wind, and a temperature of about 16°C. The aircraft's mass at the time could not be directly measured, but was estimated at 2096 kg (4621 lbs) considering 100 liters of fuel, about 600 kg of rice seed after the first pass, basic mass, pilot, and equipment. This value exceeded the maximum authorized takeoff mass. The ELT functioned correctly, emitting a valid signal processed by the Lisboa Rescue Coordination Centre. Law enforcement (GNR) and Azambuja firefighters attended the scene.