Seaplane or Amphibian
Flight Crew Multiengine; Flight Crew Private; Flight Crew Instrument
Flight Crew Last 90 Days 11.4; Flight Crew Total 2877.7; Flight Crew Type 30.5
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Ground Strike - Aircraft
Aircraft Aircraft Damaged; General Maintenance Action; General Evacuated
Procedure; Aircraft
Upon landing seaplane Aircraft X;  I stuck an unrecognized 'rogue' wave at ZZZ. Intersecting rolling waves believed caused by wake boats created a sea state larger than usual and under-appreciated.  The seaplane bounced into the air; power was added and an uneventful touchdown was completed. The port-side float at its fuselage attach point was fractured; however; and the airplane tilted down and leftward; the prop striking the first of five float chambers; breaking a blade lodged in the float. The passenger and I exited the plane to the starboard float and the seaplane was towed to shore.  No one was injured.A significant contributing factor was the discovery post-event that the forward; port upper strut was 75% fractured and unrecognized prior to breaking.  The starboard attachment was discovered post event to have sustained a previous (estimated) 10% prior fracture. I purchased the amphibious seaplane in month; year; with approximately 665 TTA+E. At the time of the incident; I had flown the aircraft another 30.5 hours. (I have accumulated approximately XXX logged seaplane hours.) There is no inspection requirement pertaining to the float strut attachment points and the fractured area would not be visible without physically removing the floats from the aircraft.  Both the aircraft and float manufacturers were informed with a written report and photographs. It was suggested that an inspection requirement be implemented and/or a redesigned; strengthened fuselage float mount bracket be designed.Considering human performance factors; the larger than usual sea state containing nearly invisible rolling waves contributed to the incident. Though the area selected for landing was clear of all boat traffic; I (the pilot) underestimated the effect of the wave action created by the powerboats operating closer to shore on either side of the selected landing area. Had the float strut been completely intact; the bounced landing would not have been beyond the capability of pilot or seaplane. With the fracture; the incident was just waiting to happen.
Seaplane pilot reported aircraft suffered a strut failure during a difficult landing. Investigation revealed unrecognized previous fracture of its mounting bracket.