West Liberty, KY, USA
N831RS
Rans RANS S7 COURIER
While en route, about 2 hours into the cross-country flight, the engine lost all power. The pilot primed and restarted it twice; however, the engine would not sustain power. On the third attempt at restarting, the pilot noted that the propeller would not turn over, and he elected to perform a forced landing to a field. During the landing, the airplane struck a fence, which resulted in substantial damage to the left wing and engine mounts. Examination of the engine revealed that the oil injection tank was empty, and the aft piston exhibited vertical scoring, consistent with lack of lubrication. It is likely that the aft piston seized in flight as a result of a lack of lubrication, which resulted in the total loss of engine power. Leak testing of the oil system revealed no leakage; therefore, it is likely that the pilot departed on the flight without sufficient oil. Although the pilot should have checked the oil before the flight, the pilot operating handbook, which was written by the builder, contained incorrect oil consumption information, which likely contributed to the pilot's misunderstanding of the amount of oil needed for flight.
On November 15, 2019, about 1430 eastern standard time, an experimental, amateur-built Rans S7 Courier airplane, N831RS, was substantially damaged during a forced landing to a field in West Liberty, Kentucky. The private pilot was not injured. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan had been filed for the cross-country flight, which originated from Jackson County Airport (I18), Ravenswood, West Virginia around 1220, and was destined for Smyrna Airport (MQY), Smyrna, Tennessee. According to the pilot, while en route to the destination, the engine lost total power "like someone turned off" the magnetos. He primed and restarted the engine, however it only produced power for 3 to 4 seconds before it lost total power for a second time. He repeated the process again, and the engine again lost power. When he attempted to restart the engine for the third time, the propeller would not rotate to initiate the start. The pilot elected to make a forced landing to a nearby field. During the landing, the airplane struck a fence post, which resulted in substantial damage to the left wing and engine mounts. An examination of the engine by a Federal Aviation Administration inspector revealed that the propeller would rotate through 360° of motion when turned by hand. In addition, the oil reservoir was empty. Fuel samples were taken from both wings and no debris was noted in either sample of 100LL fuel. An examination of the two-stroke engine by an NTSB investigator and manufacturer representative revealed that the engine remained attached to the fuselage. The propeller could be rotated through 360° of motion and compression was confirmed on both cylinders. Fuel was noted in both carburetors that was free of debris. The spark plugs were removed, exhibited normal wear, and were not oil soaked. An examination of the oil system revealed that there were no leaks in the system and the oil injection tank was empty. There was no oil pooling in the oil ports in the carburetors. Furthermore, when the exhaust y-pipe was removed from the cylinders, the aft piston exhibited vertical scoring and was not lubricated. The front piston did not have any scoring and was slightly lubricated. The fuselage was examined, and no oil streaking was noted. Oil was added to the oil injection tank and no leaks were noted. According to the flight manual, the oil consumption of the engine was "approximately 0.2 [quarts] per hour at 5800 rpm (1 quart in 5 hours)," which converted to about 6.4 ounces of oil per hour. Furthermore, it stated that the oil tanks held about one gallon of oil and that the "oil tanks should supply enough oil for 20 hours of continuous engine operation." While examining the engine it was noted that there was only one oil tank and it could contain about 2 quarts of oil. No other oil tank that injected into the pistons was noted on the airplane. There were no maintenance entries that mentioned any oil tank maintenance in the logbooks. According to the engine operator's manual, the engine oil injection would be 8.2 cubic inches of oil per hour per outlet, which, with two outlets, converted to about 9 ounces of oil per hour. The preflight checklist stated to check the engine oil, hoses, wires, and cables prior to engine start.
The pilot's failure to verify that the engine oil tank contained adequate oil for the cross-country flight, which resulted in a total loss of engine power as a result of lack of lubrication. Contributing to the accident was the incorrect oil consumption information listed in the pilot operating handbook.
Source: NTSB Aviation Accident Database
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