# NTSB CEN11LA050: Mcfarland Bill Challenger II, N448WM, Praire Du Sac, WI, November 1, 2010 - Type: NTSB accident investigation - Classification: Accident · Fatal · Limited investigation · Final report - Date: November 1, 2010, 14:15 local (19:15 UTC) - Place: Praire Du Sac, WI - Coordinates: 43.346389, -89.753334 - Nearby events: https://openairdocs.org/map.md?lat=43.3464&lon=-89.7533&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Aircraft structural failure](https://openairdocs.org/ntsb-events/337) - Highest injury: Fatal - Injuries: 1 fatal - Status: Completed, report August 7, 2012 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA - Milwaukee FSDO - NTSB case key (mKey): 77712 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN11LA050 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/77712/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=77712 - Page: https://openairdocs.org/ntsb/CEN11LA050 ## Probable cause The separation of the fuselage-mounted wing strut attachment fitting for an undetermined reason, which resulted in the separation of the left wing of the airplane. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined (probable cause); cases with it: [Mcfarland Bill CHALLENGER II, 1 case](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=05615B0), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) - [Fuselage: wing attach fittings (on fus)](https://openairdocs.org/ntsb-findings/01035341): Aircraft › Aircraft structures · Failure (probable cause); cases with it: [Mcfarland Bill CHALLENGER II, 1 case](https://openairdocs.org/ntsb-findings/01035341/cases.md?model=05615B0), [All aircraft, 2 cases](https://openairdocs.org/ntsb-findings/01035341/cases.md) - [Wing structure](https://openairdocs.org/ntsb-findings/01035700): Aircraft › Aircraft structures · Failure (probable cause); cases with it: [Mcfarland Bill CHALLENGER II, 1 case](https://openairdocs.org/ntsb-findings/01035700/cases.md?model=05615B0), [All aircraft, 48 cases](https://openairdocs.org/ntsb-findings/01035700/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-cruise: Aircraft structural failure](https://openairdocs.org/ntsb-events/337) (defining event); cases with it: [Mcfarland Bill CHALLENGER II, 1 case](https://openairdocs.org/ntsb-events/337/sequence.md?model=05615B0), [All aircraft, 290 cases](https://openairdocs.org/ntsb-events/337/sequence.md) - [Uncontrolled descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Mcfarland Bill CHALLENGER II, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=05615B0), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis 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. ## Factual narrative HISTORY OF FLIGHT On November 1, 2010, about 1415 central daylight time, an amateur-built McFarland Challenger II airplane, N448WM, was substantially damaged when it 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. The airplane was registered to and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight, which was not on a flight plan. The flight originated about 1400 from the Sauk Prairie Airport, Prairie Du Sac, Wisconsin, and was en route to the Merrill Municipal Airport, Merrill, Wisconsin. Witnesses reported seeing the airplane traveling north when one wing suddenly separated from the airplane. One of the witnesses stated that the other wing separated shortly after the first one. The witnesses estimated that the airplane was 300 to 500 feet above the ground prior to the first wing separation. The airplane subsequently impacted a corn field. PERSONNEL INFORMATION The pilot held a commercial pilot certificate with helicopter and instrument helicopter ratings. The pilot’s most recent second class airman medical certificate was issued on February 17, 2010. On the pilot’s application for the medical certificate, he reported 6,000 total flight hours. The pilot did not have a rating for fixed wing single engine airplanes. A friend of the pilot reported that the pilot had taken several hours of flight instruction in the accident airplane. The pilot’s flight logbook was not available for review during the course of the investigation. AIRCRAFT INFORMATION The airplane was a high wing, tricycle gear kit aircraft with a frame structure built from aluminum alloy tubing fastened with bolts and rivets and covered with fabric. The airplane was fitted with amphibious floats and could carry 2 occupants in a tandem seat arrangement. The 65-horsepower Rotax 582 engine was mounted in pusher configuration. According to Federal Aviation Administration records, the airplane was initially certified in the experimental amateur-built category on July 14, 2004. The airplane was sold to the pilot by the widow of the original builder on August 20, 2010. METEOROLOGICAL INFORMATION A review of recorded data from the Baraboo Wisconsin Dells Airport automated weather observation station, elevation 979 feet, revealed that at 1415 the weather conditions were: calm wind; 10 miles visibility; scattered clouds at 3,200 feet above ground level; temperature 8 degrees Celsius; Dew Point 0 degrees Celsius; altimeter setting 30.42 inches of mercury. WRECKAGE AND IMPACT INFORMATION The airplane impacted a harvested cornfield. The components came to rest in 3 major groupings; the left wing, right wing, and fuselage. The fuselage structure was upright with the lower fuselage crushed upward. The rudder and vertical stabilizer remained attached to the aft fuselage of theairplane. The right horizontal stabilizer and elevator had separated from the airplane and were found next to the left wing. The left horizontal stabilizer and elevator were separated from the airplane but were located next to the aft fuselage at approximately their normal installed position. Both wings were completely separated from the airplane with the exception of the right wing aft spar and aileron. The internal structure of the right wing remained attached to the forward spar. The right wing aft spar and control surfaces remained attached to the fuselage. The forward right wing attach fitting was fractured. The left wing was separated from the fuselage and both wing attachment fittings were fractured. The fabric covering was torn and a large portion of the lower wing fabric covering was found a short distance away. The left rear spar and control surfaces exhibited uniform bending along the entire span that resulted in an upward curvature. Components retained for further examination included 9 wing attachment fittings that exhibited deformation or fracture at the accident scene. Examination of the wing fittings by a specialist in the National Transportation Safety Board's Materials Laboratory revealed signatures consistent with overload failure on all parts exhibiting fractures. The parts that were not fractured exhibited evidence of plastic deformation, with the exception of one fitting that had no perceptible damage due to deformation or fracture. That fitting was the left-rear-lower wing strut attachment fitting that connected the wing strut to the fuselage. The attachment bolt for this fitting was not recovered. A piece of fabric covering material from the left wing was also retained for testing. A portion of the fabric was sent to a commercial laboratory to perform the ASTM D 5035-08 Breaking Strength of Textile Fabrics (1" Cut Strip Method). The results of this test indicated an average breaking strength of 67.75 pounds. Federal Aviation Administration minimum performance standards for new intermediate grade fabric are specified in TSO-C14B “Aircraft Fabric Intermediate Grade” and indicate a minimum of 65 pounds as the requirement when applicable. No preaccident defects were found with regard to the components examined. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy of the pilot was performed on behalf of the Sauk County Coroner by the University of Wisconsin School of Medical and Public Health, on November 2, 2010. The pilot’s death was attributed to injuries received in the accident. Toxicology testing was performed by the FAA Civil Aerospace Medical Institute. Testing results were negative for all substances in the screening profile. ## Aircraft - Registration: [N448WM](https://openairdocs.org/deregistered/N448WM-2012-07-24), registration cancelled 2012-07-24, S/N CH2-1002-2263, built 2004 (OpenAirDocs) - Reported make and model: MCFARLAND BILL CHALLENGER II - Registry model: [Mcfarland Bill CHALLENGER II](https://openairdocs.org/model/mcfarland-bill-challenger-ii) (registry code 05615B0) (OpenAirDocs) - Registry engine: [Bombardier ROTAX (ALL)](https://openairdocs.org/engine/bombardier-rotax-all) (registry code 09050, reciprocating) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: CH2-1002-2263 - Engines: BOMBARDIER ROTAX (ALL) 65 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, August 16, 2010 - Departed: 91C, Prairie Du Sac, WI - Destination: RRL, Merrill, WI ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 51; injuries: fatal; commercial; instrument ratings: helicopter; medical: class 2, with waivers/limitations; toxicology performed; flight hours: 6,000 total ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 46 °F, dew point 32 °F - Altimeter: 30.42 inHg - Observed at: DLL, 10 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20101101050989A](https://openairdocs.org/incident/20101101050989A), Nov 1, 2010: Mcfarland B CHALLENGER, Prairie Du Sac, WI, Destroyed, 1 fatal. On November 1, 2010 at 14:15 CDT, the pilot of an amatuer bulit Challenger ii experienced an in flight breakup 3 miles north of the Sauk-Prairie Airport,… ## Docket (14 files) The files NTSB released with the investigation on June 7, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=77712. 30.1 MB in all. - Materials Laboratory Report 11-044 (7 photos) (item 1, .PDF, 7 photos, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40355035&FileExtension=.PDF&FileName=Materials%20Laboratory%20Report%2011-044%20(7%20photos)-Master.PDF - Witness Statements (item 2, .PDF, 547 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369343&FileExtension=.PDF&FileName=Witness%20Statements-Master.PDF - Statement from Flight Instructor (item 3, .PDF, 119 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369336&FileExtension=.PDF&FileName=Statement%20from%20Flight%20Instructor-Redacted.PDF - Sauk County Sheriff Report (item 4, .PDF, 781 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369346&FileExtension=.PDF&FileName=Sauk%20County%20Sheriff%20Report-Redacted.PDF - Wreckage scene - photo 1 (provided by Sauk County Sheriff's Department) (item 5, .PDF, 4.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369325&FileExtension=.PDF&FileName=Wreckage%20scene%20-%20photo%201%20(provided%20by%20Sauk%20County%20Sheriff%27s%20Department)-Master.PDF - Wreckage scene - photo 2 (provided by Sauk County Sheriff's Department) (item 6, .PDF, 3.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369327&FileExtension=.PDF&FileName=Wreckage%20scene%20-%20photo%202%20(provided%20by%20Sauk%20County%20Sheriff%27s%20Department)-Master.PDF - Wreckage scene - photo 3 (provided by Sauk County Sheriff's Department) (item 7, .PDF, 4.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369328&FileExtension=.PDF&FileName=Wreckage%20scene%20-%20photo%203%20(provided%20by%20Sauk%20County%20Sheriff%27s%20Department)-Master.PDF - Wreckage scene - photo 4 (provided by Sauk County Sheriff's Department) (item 8, .PDF, 4.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369330&FileExtension=.PDF&FileName=Wreckage%20scene%20-%20photo%204%20(provided%20by%20Sauk%20County%20Sheriff%27s%20Department)-Master.PDF - Wreckage scene - photo 5 (provided by Sauk County Sheriff's Department) (item 9, .PDF, 3.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369331&FileExtension=.PDF&FileName=Wreckage%20scene%20-%20photo%205%20(provided%20by%20Sauk%20County%20Sheriff%27s%20Department)-Master.PDF - Wreckage scene - photo 6 (provided by Sauk County Sheriff's Department) (item 10, .PDF, 2.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369332&FileExtension=.PDF&FileName=Wreckage%20scene%20-%20photo%206%20(provided%20by%20Sauk%20County%20Sheriff%27s%20Department)-Master.PDF - Airworthiness Information (item 11, .PDF, 2.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369333&FileExtension=.PDF&FileName=Airworthiness%20Information-Redacted.PDF - Registration Information (item 12, .PDF, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369335&FileExtension=.PDF&FileName=Registration%20Information-Redacted.PDF - Aircraft Bill of Sale (item 13, .PDF, 167 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369337&FileExtension=.PDF&FileName=Aircraft%20Bill%20of%20Sale-Redacted.PDF - Toxicological Report (item 14, .PDF, 104 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40369334&FileExtension=.PDF&FileName=Toxicological%20Report-Redacted.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.