NTSB Identification: LAX08LA179
14 CFR Part 91: General Aviation
Accident occurred Thursday, June 12, 2008 in Beaver, UT
Probable Cause Approval Date: 06/11/2009
Aircraft: CESSNA 172S, registration: N233GW
Injuries: 1 Serious,2 Minor.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The pilot obtained the local weather information and observed the windsock. Another airplane had just landed on runway 13, and with the weather information, he determined that he would take off on runway 13. The pilot said that he used a short-field takeoff technique with zero flaps, and the airplane encountered a wind gust and windshear conditions. The engine momentarily lost power and sputtered, and he checked the mixture control to make sure that it was at the full rich position and that the throttle was in. He maneuvered to avoid power lines and a circular agricultural irrigation system. The airplane then quickly lost altitude and the pilot nosed the airplane over to avoid a stall. The airplane impacted terrain about 2,850 feet from the end of runway 13, and approximately 1,000 feet to the right of runway centerline, damaging the firewall, wings, and crushing the fuselage bottom. Examination of the airframe, engine, and its fuel control unit identified no preexisting anomalies. The 4,984-foot-long paved runway had an uphill gradient of 1.5 percent and was at an elevation of 5,863 feet. The reported wind at the airport was from 330 degrees at 8 knots, gusting to 14 knots. The density altitude was calculated at 7,457 feet. The pilot who landed just before the accident said that the winds were variable between 330 to 350 degrees at 5 to 10 knots. He further reported that the sky conditions were clear and that he observed no windshear or hazardous conditions around the airport. The terrain surrounding the airport was flat agricultural land, which was gently rising to the south, about 150 feet per nautical mile. The airplane was near its maximum gross weight. The Pilot's Operating Handbook for the airplane states that prior to takeoff from fields above 3,000 feet elevation, the mixture should be leaned to give maximum rpm in a full throttle, static run up. According to the engine manufacturer, if the engine is properly leaned for a density altitude of 7,457 feet, the normally aspirated engine's maximum output of 180 horsepower (hp) would be reduced to 138 hp. Since the engine was not leaned, but was operating at full rich mixture, its output would have been reduced even further, thus not allowing the airplane to outclimb the rising terrain for the existing conditions.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's failure to attain and maintain an adequate airspeed during the initial climb as a result of his inadequate preflight planning and improper use of the mixture control. Contributing to the accident were the tailwind and high density altitude. Full narrative available
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