As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN)ON FIRST POWER REDUCTION AFTER AIRBORNE ON FLOATS, ENGINE LOST POWER. AIRCRAFT LANDED AND WATER TAXIED BACK TO DOCK. #2 CYLINDER EXHAUST VALVE FAILED. HALF OF VALVE FACE WAS MISSING. TOP OF PISTON PEE NED BY VALVE PIECES BOUNCING AROUND IN CYLINDER.