West Jordan, UT, USA
N31TE
Beech N35
Prior to takeoff, the pilot obtained a weather briefing from the flight service station. Witnesses, who were located on the airport, reported that shortly after takeoff, the airplane was 150 feet agl and flying runway heading. The right wing was low, landing gear extended, and the nose in a climb attitude, but the airplane was not climbing. As the airplane approached the end of the runway, the airplane lost altitude and "was still mushing along." The right wing then rolled to an almost vertical attitude, the nose dropped, the airplane rolled to the left and impacted terrain. One witness stated there were no mechanical problems with the airplane and the engine sounded normal. The airplane was destroyed by postimpact fire. Examination of the airframe and engine revealed no anomalies that would have precluded normal operation. The airplane was 126.2 lbs over gross weight at the time of the accident. Witnesses reported gusty wind conditions, thunderstorms in the area, and no precipitation. Weather data revealed environmental conditions that supported dry microburst activity at the time of the accident.
HISTORY OF FLIGHT On July 24, 2005, approximately 1620 mountain daylight time, a Beech N35 single-engine airplane, N31TE, was destroyed when it impacted terrain following a loss of control during takeoff from Salt Lake City Municipal Airport #2 (U42), near West Jordan, Utah. The private pilot, a pilot-rated passenger, and another passenger sustained fatal injuries. The airplane was registered to and operated by the pilot. Visual meteorological conditions prevailed, and a flight plan was not filed for the Title 14 Code of Federal Regulations Part 91 personal flight. The flight was originating at the time of the accident. According to a local fixed based operator (FBO), the airplane arrived at U42, on July 22, 2005, approximately 1130. According to a credit card receipt, the airplane was filled with $140.11 of 100LL aviation fuel. FBO personnel stated the airplane remained parked until the day of the accident. FBO personnel stated that on the day of the accident, the pilot and one passenger arrived at the airport approximately 1300. The pilot returned his rental car, waited for another passenger, and spent approximately 2 hours in the "weather room" at the FBO. A witness, who was located on the airport, reported the airplane departed runway 16. Approximately 2,000 feet down the runway, the airplane was 150 feet agl and flying runway heading. While at 150 feet agl, "the right wing was low, gear down, and nose in a climb attitude, but not climbing." The right wing was down for almost the entire length of the runway. As the airplane approached the end of the runway, the airplane lost altitude, was approximately 50 feet agl, and "was still mushing along." The right wing then rolled to an almost vertical attitude, the nose dropped, the airplane rolled to the left and impacted the terrain. The airplane appeared to impact the ground with the nose and left wing. The witness reported the wind was approximately 35-40 knots from a west-northwest direction at the time of the accident airplane's takeoff. Another witness, the wife of one of the passengers, reported to local authorities that she typically watched her husband take off. Located near the FBO during the takeoff, the witness observed the airplane remain low and level near the south end of the runway. She thought to herself, "good [pilot] stay level and low because the altitude is different here compared to California." She watched the airplane wobble two times and then strike the ground in the dirt mounds prior to the airport perimeter fence. She stated there were no mechanical problems during the takeoff, and the engine sounded "normal." According to a pilot who landed at U42 just prior to the accident airplane's takeoff, the airport UNICOM reported 10 knot winds from 220 degrees and gusting to 12-15 knots. During landing to runway 34, the pilot experienced light turbulence. The pilot stated, "at no time did we experience wind shear or change in wind direction." After landing, the pilot reported the winds "continued westerly and appeared steady." PERSONNEL INFORMATION The pilot held a private pilot certificate with airplane single-engine land and instrument ratings. The pilot was issued a second-class medical certificate on April 9, 2004, with the limitation, "Must Wear Corrective Lenses." The pilot's logbook was not located; however, a review of the pilot's insurance records, dated May 1, 2004, revealed the pilot had accumulated 5,000 total flight hours, and 4,000 hours in the accident airplane make and model. According to the pilot's last medical application, the pilot reported 5,000 total flight hours. AIRCRAFT INFORMATION The 1961-model Beech N35, serial number D-6745, was a single-engine, low wing, V-tail, retractable landing gear, semi-monocoque design airplane. The airplane was powered by a six cylinder, air-cooled, horizontally opposed, fuel-injected Teledyne Continental Motors IO-520-BB (2), (serial number 274578-R), engine, rated at 285 horsepower, and equipped with a three-bladed constant speed propeller. The airplane was configured to carry a maximum of four occupants. Maximum gross weight for the airplane was 3,125 pounds (lbs). The airplane was issued a standard airworthiness certificate on July 27, 1962, and was certificated for normal category operations. The airplane's current registration was issued to the pilot on April 25, 1985. The airframe, engine, and propeller logbooks were not located. METEOROLOGICAL INFORMATION Approximately 1400, the pilot obtained a weather briefing from Cedar City Flight Service Station. At 1505, the Salt Lake City Center (KZLC) Center Weather Service Unit issued Center Weather Advisory number 101 which was valid until 1605. The advisory was issued for an area of thunderstorms 30 miles wide from SLC to 50 miles south of SLC. The thunderstorms were identified as having tops to 38,000 feet and were moving from 260 degrees at 10 knots. At 1537, the National Weather Service (NWS) Salt Lake City Regional Forecast Office issued a short term forecast. According to the forecast, the area of Salt Lake, Tooele Valleys, and southern Wasatch Front was area of potentially strong thunderstorms that had developed over western Salt Lake and northwest Utah counties. The storms could produce locally heavy rain and gusty surface winds through 1615. At 1555, Convective SIGMET 75W was issued for portions of Colorado, Wyoming, and Utah, which was valid until 1755. The accident site resided on the northern border of the advisory. The advisory was issued for an area of thunderstorms moving from 240 degrees at 15 knots, with tops to 44,000 feet. At 1556, the Salt Lake City International Airport (SLC) automated surface observation system (ASOS), located approximately 10 miles north of U42, reported wind calm, visibility unrestricted at 10 miles, scattered clouds at 9,000 feet, ceiling broken at 13,000 feet and 20,000 feet, temperature 33 degrees Celsius, dew point 11 degrees Celsius, and altimeter setting of 29.99 inches of Hg. The following remarks were included: lightning distant southeast through southwest, thunderstorm distant southeast through southwest moving east, and towering cumulus clouds distant north through southeast. The calculated density altitude was 7,756 feet. At 1626, the short term forecast reported that thunderstorms would continue across Salt Lake and northern Utah counties through 1700. The storms could produce locally heavy rain and gusty surface winds. At 1639, the SLC ASOS reported wind from 210 degrees at 17 knots, visibility unrestricted at 10 miles, scattered clouds at 9,000 feet, ceiling broken at 13,000 feet and 20,000 feet, temperature 33 degrees Celsius, dew point 10 degrees Celsius, and altimeter setting of 29.98 inches of Hg. The following remarks were included: wind shift at 1619, cumulonimbus clouds distant east through southeast moving east, and towering cumulus clouds distant north through east. The calculated density altitude was 7,755 feet. The Geostationary Operations Environment Satellite number 12 data was obtained from the National Climatic Data Center. Both visible and infrared imagery was obtained surrounding the time of the accident. The satellite imagery surrounding the time of the accident from 1500 to 1645, approximately every 15 minutes, were reviewed. At 1610, the infrared image depicted an enhanced area of clouds associated with cumulonimbus clouds over the accident site with cloud tops in the range of 33,000 feet. The visible image depicted the accident site on the edge of a cumulonimbus cloud. A few overshooting domes are observed in the anvil an indication of an active mature stage storm with strong updrafts. The area forecast, valid at the time of the accident, for northwestern Utah was for scattered to broken clouds at 12,000 to 14,000 feet, with tops to 25,000 feet, with widely scattered thunderstorms and light rain showers, with cumulonimbus cloud tops to 40,000 feet. The closest upper air sounding or rawinsonde observation (ROAB) was from the NWS at SLC at 1800. The stability indices indicated an unstable environment favorable for thunderstorm development. The energy analysis of the sounding supported a moderate risk of thunderstorms. The maximum vertical velocity of the potential convective updrafts in the thunderstorms was determined to be 66 knots. The microburst potential measure of the downdraft instability indicated a strong potential for dry microbursts with estimated outflow winds near 65 knots. A dry microburst is defined as a microburst with little or no precipitation reaching the ground; most common in semi-arid regions. A witness, who was driving in a vehicle on a roadway adjacent to the airport, reported that at the time of the accident they experienced "a gust of wind, a microburst of rain, and lightning strikes." Another witness located in a vehicle stated, "The winds were erratic, variably strong. The prevailing wind was from the south and there were many passing thunderstorms with virga coming down from the clouds all around. No precipitation." AERODROME INFORMATION The Salt City Municipal 2 Airport, U42, is a public uncontrolled airport located 7 miles southwest of Salt Lake City, Utah, at 40 degrees 37.10 minutes north latitude, 111 degrees 59.34 minutes west longitude, at a surveyed elevation of 4,607 feet msl. The airport features a single asphalt runway, runway 16/34, which is 5,860 feet long and 100 feet wide. WRECKAGE AND IMPACT INFORMATION The airplane impacted an area of fill dirt, a rising embankment, and an airport perimeter fence, and came to rest located approximately 2,000 feet from the departure end of runway 16 on the side of a city road. The geographic coordinates of the airplane wreckage were 40 degrees 36 minutes north latitude and 111 degrees 59 minutes west longitude. The initial impact was located within the area of fill dirt and was consistent with the left wing tip. The outboard portion of the left wing, the nose landing gear and right main landing gear were separated and located in the debris path. The wreckage debris path measured approximately 300 feet in length on a measured magnetic heading of 140 degrees. The main wreckage came to rest on a magnetic heading of 330 degrees. The main wreckage consisted of the fuselage, right wing, a portion of the left wing, the empennage, and engine. The airplane was destroyed by a post-impact fire. The inboard portion of the left wing remained attached to the fuselage. The left flap remained attached to the inboard left wing, and the left aileron was separated from the outboard section of the left wing. The left wing tip was destroyed. The left main landing gear remained attached to the inboard left wing and was consumed by fire. The right wing remained attached to the fuselage and was consumed by fire. The right flap and aileron were attached to the wing and were consumed by fire. The right flap actuator was measured and corresponded to a flaps up condition. The empennage was attached to the fuselage. The left and right stabilizers and ruddervators were attached and consumed by fire. The ruddervator trim actuator was measured and corresponded to a 3 degrees nose up trim setting. The fuselage, cabin, and instrument panel were destroyed by fire. A single control wheel was found in the cockpit. One control wheel chain and sprocket were found in the fire consumed control column, consistent with the airplane equipped with a single control wheel. Both aileron cables remained attached to the control wheel chain and were intact to their terminating ends. The elevator control cables remained attached to the control column assembly to the aft mixer assembly. The aft pushrods remained attached to the mixer assembly and were separated from the ruddervator torque fittings. The right rudder cable separated from the forward rudder bellcrank. The terminating end was located in the cockpit and was intact. The left rudder cable remained attached to the bellcrank, and both rudder cables were intact to the mixer assembly. The landing gear retract rods about the landing gear motor assembly were found consistent with the landing gear in the extended position. All four seats remained attached to their respective seat tracks. None of the seat belts or buckles were located; however, according to the local authorities, all three occupants remained in their seats. The engine was separated from its respective engine mounts, and was found bent around to the left of the fuselage. The engine came to rest on its right side and displayed thermal damage. The engine accessories were removed, and the engine was rotated by hand. Thumb compression and valve train continuity was established to the number 1,2,3,4,5 cylinders. The number 6 cylinder intake valve seat was displaced within the cylinder head. The fuel pump, vacuum pump, propeller governor, and oil pump were rotated by hand. Continuity to the fuel system was not established due to thermal damage. The propeller assembly remained attached to the engine crankshaft. Two propeller blade tips were separated. All three blades displayed leading edge gouging and chordwise surface scratches and polishing. The propeller blades were free to rotate in the propeller hub. PATHOLOGICAL INFORMATION An autopsy was performed on the pilot by the Office of the Medical Examiner, State of Utah, Department of Health, Salt Lake City, Utah, on July 25, 2005, and specimens were retained for toxicological analysis by the Federal Aviation Administration's Civil Aeromedical Institute's (CAMI) Forensic and Accident Research Center, Oklahoma City, Oklahoma. Toxicological tests were negative for carbon monoxide, cyanide, and ethanol. An unspecified amount of Quinine, and 47.21 (ug/ml, ug/g) of Acetaminophen (commonly known as Tylenol) was detected in the urine. TEST AND RESEARCH A Basic Empty Weight and Balance sheet from the Pilot's Operating Handbook was located in the wreckage. Hand written weights and calculations were noted on the sheet; however, no revision date was found. The sheet listed a basic empty weight of 2,160.0 lbs. All baggage and personnel effects were gathered from the wreckage and were weighed with a digital scale. The baggage and personnel effects were partially consumed by fire. The weight of the baggage and personnel effects was 111.2 lbs. Adding the basic empty weight, fuel, baggage, and occupants weights resulted in a total of 3,251.2 lbs, which was 126.2 lbs over gross weight. Due to the lack of an arm listed for the basic empty weight, a center of gravity calculation could not determined. A Garmin hand-held global positioning system (GPS) GPSmap 295, serial number 98803597, was found on the gravel shoulder of the city road adjacent to the main wreckage. The GPS was shipped to Garmin's manufacturing facility to extract any available data. According to Garmin, the unit contained 73 waypoints, 4 stored routes, and 1,023 track points. The unit contained 472 track points recorded on July 22, 2005. No data was recorded for the accident flight. ADDITIONAL INFORMATION The FAA Aeronautical Information Manual (AIM), chapter 7, Safety of Flight, section 7.1.26 "Microbursts," is provided for reference. "Microbursts are small scale intense downdrafts which on reaching the surface, spread outward in all directions from the downdraft center. This causes the presence of both vertical and horizontal wind shears that can be extremely hazardous to all types and categories of aircraft, especially at low altitudes. Microbursts commonly occur within the heavy rain portion of thunderstorms, and in much weaker, benign appearing convective cells that have little or no precipitation reaching the ground. They may be embedded in heavy rain associated with a thunderstorm or in light rain in benign appearing virga. When there is little or no precipitation at the surface accompanying the microburst, a ring of blowing dust may be the only visual clue of its existence." According to FAA Advisory Circular AC 00-54, "Pilot Windshear Guide," a dry microburst is one "associated with high based convective clouds located
the pilot's improper preflight planning, his attempted flight into adverse weather conditions, and the stall resulting in the loss of control and subsequent crash. Factors contributing to the accident were the pilot's inadequate evaluation of the weather conditions, the airplane exceeding its gross weight limitations, and the dry microburst from thunderstorms located near the airport.
Source: NTSB Aviation Accident Database
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