NYC95LA028

The pilot departed an airport and at approx 700 ft AGL, the engine lost power. The pilot made a 180 degree turn and contacted trees 30 ft high, 200 feet before the end of the runway. Post accident examination revealed the piston in the forward cylinder of the two stroke engine had seized due to a lean mixture.

On October 15, 1994, at 1105 eastern daylight time, an experimental, homebuilt, Rans S-10, N104AH, owned and operated by Alison Hine, of Stratham, New Hampshire, lost power after takeoff, and struck trees. The airplane received substantial damage. The certificated private pilot and passenger were not injured. Visual meteorological conditions prevailed and no flight plan had been filed for the flight which operated under 14 CFR Part 91.

In the NTSB Accident report, the pilot stated:

...At approx. 700 feet altitude, the engine stopped. There was no sputtering or coughing, it simply stopped. Believing it had seized, I did not attempt to restart it, but concentrated on landing. From previous testing, I knew I could accomplish a 180 degree turn from less than 700 feet. With no known suitable landing areas ahead, I immediately lowered the nose and executed a 180 degree turn, and established a glide towards the runway. Approximately 200 feet before the end of the runway, the aircraft contacted the tops of trees about 30 feet from the ground. The contact apparently on the nose and left wing, rotated the aircraft 90 degrees to the left. The aircraft contacted the ground in this attitude, striking right wing first....

Under the section of the report titled, "Mechanical Malfunction Failure", the pilot stated:

The forward piston [two stroke engine] seized in the cylinder. The seizure occurred in the area adjacent to the center of the exhaust port, indicating a too-lean mixture...

On January 31, 1993, FAA Airworthiness Inspector Arnold C. Silverstone, of the Portland, Maine, Flight Standards District Office, meet with the pilot. In a letter he stated:

...I observed that the forward piston showed evidence of overheating to the extent of melting the aluminum on the sides of the piston. The cylinder wall was scored from a binding condition as the piston overheated and finally seized. A very plausible hypothesis is that the forward carburetor experienced diminished fuel supply and the mixture became too lean, causing the overheating condition. How this lean mixture situation may have developed is completely described in a very comprehensive report prepared by Alison Hine. I retraced the scenario in the report using the actual aircraft system, all things appear to be accurate and factual as described.

In a detailed report submitted by the pilot, she reported finding air in the fuel line to the forward carburetor, and that the carburetors are supplied fuel by a Mikuni dual-output pump driven by a pulse line from the aft crankcase. Additionally, she noted that the fuel vent lines were off alignment by approximately 20 degrees each; however, she continued that due to impact damage she could not be positive that this was a pre- impact condition.