Loss of Control in Flight · NTSB CEN11LA050
MCFARLAND BILL CHALLENGER II — Praire Du Sac, WI
| Date | November 1, 2010 |
| Location | Praire Du Sac, WI |
| Aircraft | MCFARLAND BILL CHALLENGER II (amateur-built) |
| Purpose of flight | Personal |
| Conditions | Day · Visual Meteorological Cond |
| Phase / occurrence | Uncontrolled descent Collision with terr/obj (non-CFIT) |
| Pilot age | 51 |
| Pilot total time | 6,000 hrs · High time |
| Time in type | Unknown |
| Fatalities | 1 |
Probable cause
NTSB findings
- Not determined-Not determined-(general)-(general)-Unknown/Not determined - C
- Aircraft-Aircraft structures-Fuselage-Wing attach fittings (on fus)-Failure - C
- Aircraft-Aircraft structures-Wing structure-(general)-Failure - C
What happened
The airplane impacted the ground following an in-flight separation of the left wing during cruise flight. The pilot, who was the sole occupant, was fatally injured. Witnesses reported seeing the airplane traveling north, about 300-500 feet above ground level, when one wing suddenly separated from the airplane. One of the witnesses stated that the other wing separated shortly after the first one. Postaccident examination confirmed that both wings were completely separated from the airplane with the exception of the right wing aft spar and aileron. Examination of the fractures in the wing attachment fittings revealed signatures consistent with overload failure with the exception of one fitting that had no perceptible damage due to deformation or fracture. The attachment bolt for the fitting that showed no perceptible overload damage was not recovered during the investigation; however, the relative lack of damage to the strut fitting indicates that the attachment bolt either failed, or its corresponding nut had loosened and separated during the flight. A portion of wing fabric retained for testing showed that the fabric met the minimum performance requirements as set forth in regulations. No preaccident defects were found with regard to the components examined.