Accident Overview
After takeoff, the aircrew flew to the southern end of Lake Winnebago where they conducted several uneventful water landings. The wind was estimated from the northeast at 5 to 6 knots, and the water was smooth with only small ripples.
The Accident Sequence
On the sixth approach, the landing gear handle was checked in the up position and the amber gear up indicator light was illuminated. The amphibious aircraft touched down on the water with no bounce or porpoise. Approximately two to three seconds after touchdown, the aircraft yawed violently to the right and rolled left. The left float and wing tip struck the water, causing the left wing to separate. The hull then rolled over, but the occupants egressed before the aircraft sank.
Post-Accident Examination
A diver observed that the right landing gear was extended. After the aircraft was recovered, the right main gear actuator rod clevis was found to have fractured. The fracture surface exhibited signs of overload failure. The lock nut had been screwed tightly against the clevis, and the lock nut threads had produced gouge marks on the unthreaded portion of the clevis shank.
Official Findings
The investigation identified two occurrences. The first was an airframe/component/system failure or malfunction during the landing phase. Specific findings included an overload of the landing gear normal retraction/extension assembly, improper installation by other maintenance personnel, and a loose main landing gear. The second occurrence was a loss of control on the ground/water during landing.