ERA20LA328 · Rockwell S2R

The pilot was ferrying the airplane for its new owner. According to the pilot, before the flight, he topped off the fuel and visually checked that the fuel tanks were full after allowing for equalization. He also noted that the fuel quantity indication system was inoperative. About 1 hour 35 minutes to 1 hour 45 minutes after takeoff, the airplane was cruising about 2,500 ft mean sea level when the engine lost total power. The pilot had been flying at a cruise power setting of 30 inches of manifold pressure at 2,000 rpm the entire flight. After the engine power loss, the pilot established best glide speed, shut off the fuel selector, and landed in a clearing in a forest. During the landing roll, the right wing struck a felled tree, which resulted in substantial damage to the fuselage and the right wing. Examination of the airplane and engine did not reveal any evidence of preimpact mechanical failures or malfunctions that would have resulted in a loss of power. It did reveal that the fuel tanks were empty of fuel, that the fuel strainer did not contain any fuel, and that the carburetor float bowl contained only 3 to 4 ounces of fuel. Both magnetos from the dual-magneto ignition system were tested and found to be functional. The left magneto "P" lead was found to have erratic indications when the magneto switch was placed in the BOTH or L positions. The reason for the erratic indications was an intermittent short between the shielding and the center conductor. This intermittent short would have occasionally led to intermittent operation of the left magneto; however, the right magneto would have continuously provided ignition spark during the flight. According to the previous airplane owner, if the pilot did not stop to refuel between the departure point and where the accident occurred, he was at risk of running out of fuel. He explained that the airplane’s engine was a geared radial engine that burned a large amount of fuel, typically about 50 gallons per hour. The previous owner also explained that the pilot departed before he arrived at the airport, so he did not go over the airplane with the pilot. He stated that there was a pilot’s operating handbook (POH) in the airplane. According to the new airplane owner, he had talked with the pilot the previous day and suggested the pilot study the POH regarding fuel burn and that the first leg of the flight be limited to 1 hour to ensure the actual fuel burn was as expected. The pilot later reported that, although he knew that the fuel quantity indicating system was inoperative before takeoff, he chose to fly because he "had good data as to what the aircraft's fuel burn should be per hour." The pilot also reported that although he had over 1,200 hours in the accident airplane make and model (S2R), the accident flight was the first time he had flown an S2R with a radial engine. Review of published data for the engine revealed that the maximum cruise power setting was 26 inches of manifold pressure and 2,000 rpm with a fuel burn rate of about 32 gallons per hour. Therefore, the engine power setting used by the pilot during the flight (30 inches at 2,000 rpm) exceeded the published maximum setting and would have markedly increased the rate of fuel consumption. The pilot’s decision to operate the engine beyond the indicated maximum power setting was likely due to his unfamiliarity with the engine installed on the airplane. The available evidence is consistent with a total loss of engine power due to fuel exhaustion.

Verbatim NTSB analysis and probable cause from the NTSB dataset