Accident Overview
On September 24, 2013, about 0920 eastern daylight time, a Beech 35-BE33 Debonair airplane, registration N8910M, conducted a forced landing in a field near Urbana, Indiana. The pilot received minor injuries, the first passenger received serious injuries, and the second passenger was uninjured. The airplane sustained substantial damage. The flight operated under 14 CFR Part 91 as a personal flight in visual meteorological conditions. The flight originated from Washington Municipal Airport (KAWG), Washington, Iowa, about 0730 and was destined for Van Wert County Airport (KVNW), Van Wert, Ohio. The pilot received flight following services from air traffic control.
Pilot Information
The pilot, age 62, held a private pilot certificate with ratings for single-engine land airplanes. He was issued a third-class medical certificate on May 10, 2012, with a limitation to wear corrective lenses. His most recent flight review was completed in the accident airplane on May 28, 2012. According to the pilot, he had accumulated 1,348 total flight hours and 126 hours in the make and model of the accident airplane.
Aircraft Information
The Beechcraft 35-BE33 Debonair, serial number CD-690, was a single-engine, low-wing, retractable tricycle landing gear airplane manufactured in 1963. It was powered by a Continental Motors IO-470N engine driving a three-bladed McCauley propeller. On October 10, 2008, the engine received a D-Shannon engine upgrade under Supplemental Type Certificate #SA5527SW, which included the IO-470N engine and McCauley propeller. On March 21, 2009, the propeller was removed, repaired, and reinstalled. On August 10, 2010, all cylinders were removed, de-glazed, and reinstalled. A complete top overhaul was completed on August 13, 2009, at a tachometer time of 2,158. The most recent annual inspection on the airframe, engine, and propeller was completed on November 21, 2012, with no anomalies noted.
Meteorological Information
At 0935, the weather reported at Warsaw Municipal Airport (KASW), 24 miles north of the accident site, included wind from 120 degrees at 4 knots, visibility 10 miles, sky clear, temperature 50 degrees Fahrenheit, dew point 45 degrees Fahrenheit, and an altimeter setting of 30.12 inches of mercury.
Wreckage and Impact Information
The airplane landed upright in an open bean field. The engine compartment was displaced to the left. The wings were slightly bent aft and wrinkled, and the leading edges sustained damage during the landing. The propeller was located by a land owner two months after the accident and was shipped to the engine manufacturer for examination along with the engine.
Engine Examination
The engine was shipped to Continental Motors for examination and testing. The examination, observed by the NTSB investigator-in-charge, revealed that the crankshaft was fractured forward of the number six rod journal across the oil transfer collar area. All rod journals exhibited oil starvation signatures. The number six rod had released from the crankshaft. The forward portion of the crankshaft and flange remained attached to the propeller. The crankshaft cluster gear was intact and exhibited normal operating signatures; gear bolts were tight and safety wired, and gear teeth were undamaged. The crankshaft main bearing journals were intact, undamaged, and showed normal operating signatures. The counterweight assemblies were intact and had unrestricted movement on the hanger blades. The crankcase exhibited exterior damage concentrated at the nose and the area above the number six cylinder.
Further examination of the crankshaft revealed considerable corrosion on the fracture surface. After cleaning with a strong alkaline mixture, a fatigue fracture surface indicated by beach marks was revealed. There was subsurface growth of the crack, which emanated from an area below the surface and was a secondary crack from the first crack that originated from the surface perpendicular to the axis. The crankshaft was sectioned near the initiation area, and the cross section revealed several overheating events at the surface between the fracture surface and the oil transfer hole. The presence of white untempered martensite indicated temperatures at the surface in excess of 1,400 degrees Fahrenheit, and overlapping heat-affected zones indicated several heating events.