What happened
The flight occurred the day after an annual inspection had been completed. Shortly after departure, the pilot reported that the right engine was running rough. The control tower subsequently cleared the aircraft for an emergency landing back at the airport.
While attempting to return, the pilot was unable to maintain altitude. The aircraft impacted the water approximately one mile south of the airport. According to the pilot's statement, the aircraft was flying westbound over water when the right engine stopped. The pilot secured the right engine, but approximately one minute later, the left engine also stopped. After securing the left engine, the airplane hit the water. The loss of engine power occurred approximately 15 minutes into the flight.
The investigation
An examination of the right engine revealed rusty water in the sediment bowl at the firewall. Additionally, rusty water and contamination were discovered in the corresponding fuel servo screen.
The left engine's sediment bowl was found to be dry, but its respective fuel servo screen contained rust stains, contamination, and debris described as 'trash.' Investigators found that the fuel selector valves operated without any discrepancies, and no preimpact mechanical discrepancy was found with either engine.