Marco Aviation Cessna 310R accident

The airplane experienced a total loss of engine power from both engines and was ditched in the Gulf of Mexico. According to pilot, after takeoff, the flight climbed briefly to 3,000 feet mean sea level (msl), descended to and remained at 2,500 feet msl, and then proceeded to the destination airport. When the flight was near the destination airport, the pilot reduced both throttles to 21 inches manifold pressure, and began descending at less than 500 feet-per-minute. Approximately 15 miles from the destination, while flying at 1,500 feet msl, the right engine "coughed a couple times" with corresponding right yaw. The pilot noted the right fuel flow was "down" and described a split between the left and right fuel flow readings. He reported that the left and right fuel quantity gauges indicated 70 and 100 pounds respectively, at a point just before the ditching. He turned the right auxiliary fuel pump to the low position, and moved the right fuel selector to the "left main" position in an effort to restore engine power; however, the right engine lost engine power, followed by the left engine. Following recovery of the airplane, a total of 14 ounces of fuel were drained from the left main fuel tank and no fuel was recovered from the right main fuel tank. Historical fuel records associated with the accident airplane revealed the average fuel burn was approximately 35.09 gallons-per-hour, the actual fuel load for the accident flight being only 119 pounds, instead of the pilot reported 280 pounds. The pilot did not visually inspect the fuel tanks. Rather, he relied on gauge readings and his fuel calculations, that amount only allowed approximately 34 minutes of flight at the typical power settings. Testing of components of the fuel quantity indicating system revealed no evidence of preimpact failure or malfunction. Both engines were operated postaccident with no preimpact failure or mechanical malfunction noted.

Verbatim NTSB analysis and probable cause from the NTSB dataset