Accident Overview
On July 14, 2020, at approximately 1555 Alaska daylight time, an Air Tractor AT802A airplane, registration N80166, sustained substantial damage during a firefighting flight near Birch Creek, Alaska. The pilot was not injured. The aircraft was operating under Title 14 Code of Federal Regulations Part 137 as a firefighting flight.
Aircraft Configuration
The mission-modified airplane was equipped with Wipline 10000 amphibious floats. Water scoops/probes could be manually deployed via a switch on the control stick, which actuated an electrically driven hydraulic pump. Releasing the switch retracted the scoops. Water flowed through the scoops on each float to a hopper. The aircraft also featured an asymmetric scoop warning system that would sound an audible "scoop malfunction" alert and illuminate a red warning light if scoop deployment was uneven.
Sequence of Events
According to the pilot, on the 28th scoop of the day, he touched down on the water and deployed the scoops. The airplane then veered to the right. Attempting to correct, he released the scoop switch and applied left rudder, but the veer continued. He retarded the throttle and applied reverse thrust as the airplane struck trees along the lake's shoreline. The aircraft came to rest upright in a marshy area on the shoreline, with substantial damage to the right wing.
Postaccident Examination
Postaccident examinations of the aircraft's fuel system, flight control system, and water scoop system revealed no preaccident mechanical failures or malfunctions that would have precluded normal operations. Control continuity was verified for all flight and engine controls.