What happened
During a takeoff from a lake, the pilot reported that the aircraft struck a submerged log while traveling at approximately liftoff speed. The impact caused the aircraft to become airborne at a low airspeed before dropping back onto the water surface. Upon recontact with the water, the right wing float dug into the surface, resulting in the float separating from the wing. The stress generated by this separation also caused partial detachment of the wing at the root. Consequently, the loss of the float led to the aircraft rolling inverted.
The investigation
The investigation focused on the mechanical failures following the impact. Examination confirmed that the right wing float had separated from the wing structure. Additionally, evidence indicated partial wing separation occurred at the wing root due to the stresses imposed during the incident.
Findings
Contributing factors included the presence of a submerged log in the takeoff path and the resulting structural failures. The sequence of events began with the aircraft striking the obstruction at low altitude, which initiated the chain of mechanical separations.