The flight had been arranged by one of the passengers as a scenic joy flight. The aircraft took off from the waters of Pumicestone Passage, near Bribie Island, and landed on sheltered water near South Stradbroke Island, where the occupants had lunch. During lunch one of the passengers requested that the flight continue further down the coast than had been planned. This change required a landing at Archerfield for fuel. The aircraft departed South Stradbroke Island and proceeded by the newly planned route before landing at Archerfield to refuel. The pilot has stated that after departing Archerfield he had retracted the gear. However, several witnesses reported seeing the aircraft fly overhead with the gear extended. The flight was continued to Somerset Dam where it was intended that the passengers have a swim before returning home. As the aircraft was approaching to land on Somerset Dam, witnesses observed that the four wheels were in the extended position. When the aircraft alighted on the water it immediately nosed over, then floated inverted with the floats on the surface and the cabin submerged. The pilot surfaced and immediately dived down to the cabin and freed one of the passengers. However, the efforts of the pilot and others were unsuccessful in rescuing the remaining occupants. When the aircraft was recovered from the dam numerous retraction tests were carried out on the landing gear system of the aircraft. The gear extended and retracted normally throughout these tests. However, when components of the gear system were removed from the aircraft it was found that the landing gear motor solenoid was faulty and would only operate intermittently. It is therefore considered possible that when the pilot selected the gear lever up, the gear did not actually retract. The aircraft is fitted with gear position indicators on the instrument panel as well as mechanical devices which are attached to each wheel and indicate the position of each wheel. The tests revealed that both these indicating systems were operating correctly.