NTSB Identification: WPR12FA378
14 CFR Part 91: General Aviation
Accident occurred Thursday, August 30, 2012 in Nephi, UT
Probable Cause Approval Date: 06/12/2013
Aircraft: AIRCRAFT MFG & DEVELOPMENT CO CH 2000, registration: N651AM
Injuries: 2 Fatal.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

Witnesses observed the airplane operating in the airport traffic pattern. As the airplane turned from a crosswind to a downwind leg, witnesses estimated that the airplane was about 150 feet above ground level at a slow speed when it suddenly pitched downward and descended into the ground. Witnesses further stated that at the time of the accident, thunderstorms with strong wind, heavy rain, and lightning were arriving in the area.

A regional radar mosaic for about the time of the accident depicted several scattered weather echoes with one defined cell of moderate-to-strong intensity just over the accident site. Archived lightning data for the time revealed seven in-cloud and cloud-to-ground lightning flashes within a 50-mile radius of the accident site; however, no cloud-to-ground lightning strikes were detected within 15 miles. The detection of lightning confirmed the presence of a cumulonimbus cloud in the area.

Wreckage and impact signatures were consistent with a right-wing-low and nose-low impact. Postaccident examination of the airframe, flight control system, and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. Based on the witness observations and recorded weather data, it is likely that, as a result of the approaching thunderstorm, the airplane encountered a microburst or downdraft that exceeded the airplane's climb performance and resulted in a loss of airplane control.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The pilot's inability to maintain airplane control due to an encounter with a microburst/downdraft that exceeded the climb performance capabilities of the airplane.

Full narrative available

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