History of Flight
On November 10, 2010, at approximately 1353 central standard time, an experimental amateur-built Gearn Swearingen SX300 airplane, registration N3ZX, was substantially damaged when it collided with terrain near Milford, Iowa. The pilot, who was also the registered owner and operator, sustained fatal injuries. The personal cross-country flight was conducted under 14 Code of Federal Regulations Part 91 without a flight plan. Visual meteorological conditions prevailed near the accident site. The flight departed Airlake Airport (LVN) in Minneapolis, Minnesota, at about 1240, with an intended destination of Hereford Municipal Airport (HRX) in Hereford, Texas.
Radar track data depicted the aircraft on a visual flight rules (VFR) transponder code, proceeding southwest at 8,600 feet mean sea level (msl). Around 1338, the aircraft turned west briefly before turning left to a southwest course. During this time, altitude data indicated a descent had commenced. The final radar data point was recorded at 1340:14, approximately 1 mile southeast of the accident site, at an altitude of 7,000 feet msl.
Witnesses reported hearing an airplane flying southwest. About two minutes later, they heard the engine sound increase, followed by a loud boom, and then silence. They searched the area and located the accident site. The first call to the 911 center was received at 1353. The accident site was in an open agricultural field about 8 miles west of Milford and approximately 10 miles northwest of Spencer Municipal Airport (SPW) in Spencer, Iowa.
Personnel Information
The pilot, aged 67, held a private pilot certificate with single-engine land and instrument airplane ratings. He was issued a third-class airman medical certificate on February 5, 2009, on which he reported a total flight time of 3,160 hours, with no flight time in the previous six months. The pilot's flight time logbook was not available to the NTSB.
Aircraft Information
The accident airplane was a Gearn Swearingen SX300, serial number 25, with an experimental amateur-built airworthiness certificate issued in August 1989. It was powered by a 300-horsepower Lycoming IO-540-L1C5 engine, serial number L-23211-48A.
A maintenance logbook entry dated April 20, 2009, noted the installation of the engine after overhaul and completion of a 100-hour inspection. The entry referenced a partial engine overhaul due to an overspeed event. The recording tachometer time was 155 hours, with no subsequent entries. An avionics upgrade, including installation of flat panel flight displays, was completed the day before the accident flight. The airplane had been down for approximately three months for the upgrade. A pitot static system inspection was completed before returning the airplane to service. The pilot performed a test flight the day before the accident, with only minor discrepancies noted.
Meteorological Information
Weather at Spencer Municipal Airport (SPW), about 10 miles south-southeast of the accident site, at 1353 included wind from 220 degrees at 6 knots, visibility 6 miles in light rain, overcast clouds at 2,300 feet above ground level, temperature 13°C, dew point 10°C, and altimeter 29.78 inHg. A wind shift occurred between 1353 and 1427, consistent with a cold front passage, from 220° at 6 knots to 260° at 13 knots, with a 4°C temperature drop.
A model upper-air sounding for 1500 near the accident site indicated saturated, cloudy conditions between 4,000 and 8,500 feet msl, a freezing level at approximately 8,800 feet msl, and no significant turbulence. Satellite imagery showed extensive cloud cover over western Iowa and southwestern Minnesota, with cloud tops near the accident site at about 13,000 feet msl. NOAA data indicated no icing threat at 7,000 feet msl over Iowa, but at 9,000 feet msl there was a high probability of light intensity icing near the accident site. Weather radar showed light precipitation along the flight path and near the accident site.
An AIRMET advisory for moderate icing between the freezing level and 15,000 feet msl was active at the time of the accident and included the accident site. An AIRMET for instrument flight conditions was active for an area of western Minnesota, bordering the flight path to the northwest, but not including the accident site. A Convective SIGMET warning was in effect for an area of southwestern Minnesota, also bordering the flight path to the northwest. There was no record of a preflight weather briefing for the accident flight.
Wreckage and Impact Information
The airplane was fragmented during the accident sequence. The debris field was approximately 400 yards long by 250 yards wide. The main wreckage consisted of the fuselage, engine, and empennage. The ground impact crater was about 12 feet in diameter and 4 feet deep. The engine remained attached to the airframe, but the propeller assembly separated from the engine at the crankshaft. The propeller was recovered from the impact crater; one blade had completely separated from the hub, and the remaining two blades were partially retained, all exhibiting bending.
The right wing, with aileron attached, separated and came to rest roughly 300 yards south-southwest of the main wreckage. The right flap came to rest about 200 yards east. The right horizontal stabilizer, with elevator and trim tab attached, separated and was located about 30 yards south-southeast. Fragments of the windshield and auxiliary fuel tank were found within the debris field. Flight control surfaces were recovered, and discontinuities in the flight control system appeared consistent with overload failures. No anomalies consistent with a preimpact failure or malfunction were observed.
Medical and Pathological Information
An autopsy of the pilot was performed at the Iowa State Medical Examiner's Office on November 12, 2010. The cause of death was attributed to multiple blunt force injuries due to the accident. A toxicology report from the FAA Civil Aerospace Medical Institute, with samples received on November 19, 2010, noted putrefaction. No drugs were detected in muscle tissue, and specimens were unsuitable for ethanol analysis.