What happened
While operating over open water, the aircraft experienced a sudden and total loss of oil in the left engine. This mechanical failure prevented the left propeller from fully feathering, creating significant excess drag. Because the aircraft was carrying a heavy load of fuel, the pilots were unable to maintain sufficient altitude. The combination of the unfeathered propeller and the high weight of the fuel meant that a descent was inevitable. Given the distance from land and the rate of descent, the crew was forced to execute a ditching in the ocean.
The investigation
The investigation focused on the engine failure, the impact of the aircraft's weight on its climb capabilities, and the crew's regulatory compliance. Investigators found that at the time of departure from the Sunshine Coast, the aircraft's weight exceeded the limits specified in its special ferry flight permit. While the weight decreased as fuel was consumed, the aircraft remained above the certified gross weight for which standard performance data was available.
Furthermore, the investigation identified several regulatory discrepancies regarding the crew's qualifications. Although the pilot in the left seat was the pilot in command, they lacked the necessary instrument rating required by the ferry permit. Additionally, the pilot in the right seat held an FAA licence but lacked the specific validation required to operate an Australian registered aircraft in local airspace. While these licensing issues did not cause the engine failure, they represented a failure to adhere to the safety conditions of the flight permit.
Findings
- The left engine failure resulted in a loss of oil and prevented the propeller from feathering, increasing drag.
- The aircraft was operating above the gross weight limit defined in the special ferry flight permit.
- The inability to quickly reduce the fuel load meant the aircraft lacked the performance to maintain height.
- An unapproved bladder tank was found in the nose locker, though this did not directly cause the ditching.
- The crew's qualifications did not meet the specific requirements of the special flight permit, specifically regarding instrument ratings and licence validation.