Last July, a privately registered Cessna 182 crashed at Griffith Island, killing everyone on board.
The report, released Tuesday, states that while conducting an approach to the runway, the overweight aircraft stalled and hit the water approximately 305 metres from the runway threshold.
The TSB indicates the plane was about 20 kilograms over its maximum weight, which increased the risk of stalling.
The plane also had major, undocumented modifications to the seat and safety belts. The TSB said the changes were likely done in 2000, when the aircraft was rebuilt after it was purchased from the previous owner. The plane was operated for 11 years by the previous owner and, although it had been inspected and maintained regularly, as required, the TSB said the changes were never noted.
At the time of the crash, the TSB said, the plane was "not in conformance with applicable airworthiness standards."
The force of the impact was survivable, but sufficient enough to cause extensive damage to the plane, which resulted in fatal injuries to the men in the front seats, the report said.
The TSB said the man in the back, who was wearing an improperly installed seat belt, survived the impact of the crash, but then drowned.
All three men on board were from the Sudbury area — Richard Leland Gougeon, 71, James Thornton Gougeon, 42 and pilot Richard Ross, 51.
The TSB is an independent agency that investigates marine, pipeline, railway and aviation transportation occurrences. Its aim is to advance transportation safety and not to assign fault or determine civil or criminal liability.