As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THREE MINUTES AFTER TAKEOFF, THE PILOT EXPERIENCED A LOSS OF POWER AND SLIGHT OIL ON THE WINDSHIELD IN HIS FLOAT EQUIPED ACFT. RETURNED TO THE WATER TAKEOFF AREA UNDER ITS OWN POWER. VISUALLY DETERMINED THAT 6 OF THE 10 CYLINDER BASE STUD ATTACHMENTS FOR CYLINDER NR 1 HAD FAILED.