Accident Overview
On November 26, 2014, at 1550 central daylight time, an experimental amateur-built Huebbe Sonex HB, registration N244HB, nosed-over during a forced landing on a field near Plainview, Illinois. The airplane experienced a total loss of engine power during cruise flight. The pilot sustained fatal injuries, and a sport pilot rated passenger sustained minor injuries. The aircraft was registered to and operated by the pilot under Title 14 Code of Federal Regulations Part 91 as a personal flight not operating on a flight plan. Visual meteorological conditions prevailed for the flight, which departed from Taylorville, Illinois, and was destined for St. Charles, Missouri.
Wreckage Examination
According to the Federal Aviation Administration inspector who performed an on-scene examination, the wreckage path extended about 45 to 75 feet through a cut agricultural field, then about 160 feet through a corn field. The airplane came to rest inverted with flaps extended. The inspector reported usable fuel aboard and confirmed flight control continuity.
Pilot Information
The pilot, age 66, held a private pilot certificate with a single-engine land rating and a repairman experimental aircraft builder certificate. On his last airman medical application dated May 24, 2004, he reported a total flight time of 2,500 hours, with 40 hours in the last six months. His third-class medical certificate had no limitations.
Autopsy and Toxicology
An autopsy conducted by the Macoupin County Coroner's Office reported the cause of death as "blunt force injuries to head and neck" and the manner of death as "airplane crash." The FAA Final Forensic Toxicology Fatal Accident Report detected no ethanol in vitreous, no carbon monoxide in blood, and cyanide was not performed. The report found several drugs: Diclofenac in urine; Dihydrocodeine in urine, liver, and femoral blood; Hydrocodone in urine, liver, and femoral blood; Hydromorphone in urine but not in femoral blood; and Trazodone in urine and heart blood.
Aircraft and Engine Examination
N244HB, a 2010 Sonex HB serial number 24, was built by the pilot, passenger, and the passenger's brother. The aircraft logbook noted engine installation on March 20, 2010; engine removal, lifter and cam replacement, and valve lapping on November 20, 2011; cam and lifter break-in on July 1, 2012; and the last inspection on August 10, 2014, at 300.4 hours total time.
Post-accident disassembly of the Great Plains Aircraft Supply kit engine revealed a fractured crankshaft. The crankcase halves bore the inscriptions "AS-41" and "043.101.101.A" with Volkswagen/Audi symbols. The crankshaft was sent to the NTSB Materials Laboratory for examination.
The laboratory found the crankshaft fractured through the forward cheek of the number two main bearing (numbering from the aft end). The camshaft was fractured between the number one and two lobes. The crankshaft fracture surface was flat with curved crack arrest marks, consistent with a fatigue crack initiating at the intersection of the number two main bearing journal and the forward cheek. Visual examination showed the journal-to-cheek transition consisted of a small radius fillet (approximately 0.014 inch) blended into a large radius fillet (approximately 0.090 inch). Similar dual-radius fillets were observed on the number two journal's aft cheek and the number one journal's forward cheek.
Owner Statement
The registered owner, who is the passenger's brother, stated that the engine was purchased as a kit from Great Plains Aircraft Supply Company and assembled from supplied instructions. He noted no engine serial number. Maintenance on the lifters was performed due to a notification from Great Plains regarding pitting, requiring removal of the camshaft and crankshaft. The crankshaft bearings and the crankshaft were never replaced since initial assembly.