History of Flight
On July 25, 2011, at 2036 central daylight time, a Beech model A36 airplane, N41MK, collided with terrain during a forced landing near Williston, North Dakota. The pilot was fatally injured, and the passenger sustained serious injuries. The aircraft, operated by Bonanza Air Incorporated, departed Sloulin Field International Airport (ISN) around 2018 on a local flight under day visual meteorological conditions without a flight plan. The passenger reported the flight's purpose was to take aerial photographs of an oil well installation and a cabin. After departure, the flight proceeded eastbound at low altitude. Shortly before the accident, the pilot noted abnormal engine operation and asked the passenger to locate a suitable landing area. The pilot selected an open area, and during the landing attempt, the right wing struck the terrain, causing the aircraft to slide. The passenger exited and called 911. A foreman at a nearby oil drilling site observed the aircraft flying low and straight-and-level before the impact and later assisted the passenger.
Personnel Information
The 53-year-old pilot held a private pilot certificate with single-engine land and instrument ratings. His last FAA medical examination was on February 16, 2010, with a corrective lenses restriction. According to his logbook, the pilot had accumulated 1,721.4 total flight hours, all in single-engine land airplanes, with 1,595.9 hours in the accident airplane. In the previous 90 days, he logged 25.5 hours; in the 24 hours before the accident, he flew 3.2 hours. His last flight review was completed on May 8, 2009, in the accident aircraft. No previous accidents or enforcement proceedings were on record.
Aircraft Information
The 1975 Beech A36 (serial number E-662) was powered by a 300-horsepower Continental IO-550-C engine modified with a Tornado Alley Turbo turbo-normalizing system (STC SA5223NM). It had a constant-speed Hartzell propeller and retractable tricycle landing gear. The airframe had 6,172.27 total hours; the engine had 2,619.17 total hours with 711.27 hours since a field overhaul and 115.27 hours since a top overhaul. The last annual inspection was on September 29, 2010, at 5,993.0 hours. Maintenance records showed no unresolved airworthiness issues. The aircraft was fueled on July 24, 2011, with 60.3 gallons (74 usable) before a 3.1-hour cross-country flight from Rocky Mountain Metropolitan Airport (BJC) to Sloulin Field International Airport (ISN). It was not refueled after that flight; the accident flight was the first since then.
Meteorological Information
The nearest weather station, at ISN (19.5 miles west), reported at 2052: wind 110° at 10 knots, visibility 10 miles, clear skies, temperature 26°C, dew point 14°C, altimeter 29.84 inHg.
Wreckage and Impact
The wreckage was on open, rolling terrain. The debris path began 109 feet west of the main wreckage with navigational lens cover fragments; a ground depression was 20 feet from the initial debris. The main wreckage, facing south, consisted of the entire airframe, engine, and propeller. The flaps and landing gear were retracted. Throttle, propeller, and mixture controls were full forward; magneto switch was LEFT; electric fuel pump OFF; fuel selector on left tank. The left wing tank contained about 21 gallons (18 usable); the right wing tank had minimal fuel (about 1 gallon) and was punctured. Flight and engine control continuity was established. The engine showed no preimpact mechanical malfunctions; it was removed for testing. The propeller blades had leading edge gouges and chordwise scratching.
Medical and Pathological Information
An autopsy on July 27, 2011, attributed the pilot's death to multiple blunt-force injuries. Toxicological tests detected no carbon monoxide, cyanide, or ethanol; ibuprofen was present in urine.
Tests and Research
An engine operational test run at the manufacturer under NTSB supervision showed the engine started and ran smoothly at all power settings, producing rated horsepower without hesitation. The engine monitoring system (JPI EDM-700) recorded 20 minutes of data from the accident flight. During a 24-second period, exhaust gas temperatures (EGT) and turbine inlet temperature (TIT) increased an average of 225°F before all temperatures decreased significantly. The electronic fuel flow indicator (Shadin Microflo-L) showed fuel used as 3.9 gallons and fuel remaining as 70.0 gallons, but the latter was inconsistent with the 18 gallons of useable fuel recovered from the left tank. No useable fuel remained in the right tank. Calculations based on flight tracking and engine data indicated an average fuel consumption rate of about 16.5 gallons per hour since the last refueling, consistent with the aircraft's historical average of 17.4 gph.