The ditching of a twin-engine Cessna 53 km off the coast of Queensland after one of its engines failed was inevitable due to the weight of the aircraft and the failed engine’s propeller not being able to be feathered, an ATSB investigation report details.
The twin piston-engine Cessna 421C, with two pilots on board, had departed Sunshine Coast Airport on the first leg of a transpacific ferry flight to the United States early on the morning of 10 November 2023. The aircraft had been fitted with additional fuel tanks to extend its endurance, including a large (1,134 litre) bladder tank in the main cabin, and a smaller (132 litre) tank in the nose locker. A special permit had been issued to allow the aircraft to conduct the ferry flight exceeding its certified maximum take-off weight.
When about 250 km offshore and climbing through 12,000 ft the pilots heard a muffled bang as the left engine failed. Oil was observed streaming from the engine and a large bulge had developed in the cowling.
Due to the nature of the engine failure the propeller would not fully feather, meaning it windmilled, creating excessive drag.
After turning back, the pilots identified that the aircraft could not maintain altitude and they calculated based on their rate of descent that they would be unable to reach the Sunshine Coast.
“The drag from the propeller combined with the weight of the fuel onboard meant a ditching was unavoidable as the aircraft was unable to maintain altitude on one engine,” explained ATSB Director Transport Safety Dr Stuart Godley.
The pilots notified air traffic control of their intention to ditch, with ATC in turn alerting the Joint Rescue Coordination Centre (operated by the Australian Maritime Safety Agency), which immediately began coordinating a search and rescue response.
“The pilots’ chances of surviving the ditching were enhanced by their early liaison with air traffic control and their preparation of the aircraft during its descent,” Dr Godley noted.
The aircraft was ditched in the open ocean about 53 km off the coast, with the pilots configuring the aircraft to avoid a nose down attitude on touchdown and allowing their airspeed to slow before the aircraft contacted the water.
“The pilots reported the aircraft initially skimmed the crest of a wave before it rapidly decelerated when the nose pitched into the water,” Dr Godley said.
The pilots deployed a life raft from the rear cabin before exiting the aircraft. The first of two inbound rescue helicopters arrived overhead shortly after, and winched them to safety. The aircraft sank and was not recovered.
“Impact forces during the ditching were minimised by the pilots ensuring the descent and airspeeds were managed prior to their contact with the water.”
The investigation also found that the pilots did not hold the required licence ratings and approvals to conduct the flight, and that the aircraft was not compliant with the special ferry flight permit conditions.
“However, while these factors did remove important safety defences, they did not contribute to the engine failure and the need to conduct the ditching,” Dr Godley noted.
“Nonetheless, operating outside of aviation regulations removes built-in safety defences, increasing the likelihood that undetected problems can emerge.”
Read the report: Ditching involving Cessna 421C, VH-VPY, 53 km east of Sunshine Coast Airport, Queensland, on 10 November 2023