Accident Overview
On April 1, 2010, at about 1440 central daylight time, a Beech model 95, registration N20FP, impacted a flooded ravine approximately 2 miles south of Flying Cloud Airport (FCM) near Eden Prairie, Minnesota. The flight had departed from Runway 18 at FCM, a 2,691-foot by 75-foot asphalt runway. The airplane was registered to Fisher Air LLC and operated by the pilot under 14 Code of Federal Regulations Part 91 as a repositioning flight following avionics maintenance. Visual meteorological conditions prevailed, and no flight plan was filed. The flight was originating at the time of the accident. The pilot and passenger both sustained serious injuries.
Witness and Passenger Accounts
The pilot reported no recollection of events leading up to the accident. According to the passenger, the engines seemed to reach full power during takeoff. The airplane lifted off about halfway down the runway but did not climb well. The stall warning sounded just off the end of the runway at about 50 feet above ground level (agl). The pilot appeared to check the landing gear position and auxiliary fuel pump in an attempt to troubleshoot. The pilot then reduced the pitch attitude to increase airspeed, but the airplane was unable to maintain altitude. The right wing dropped, and the airplane descended from about 300 feet agl, coming to rest in a flooded area at the bottom of a hill off the end of the runway.
A witness reported that the accident airplane's nose was pitched up about 10 to 15 degrees, with wings level, flying in ground effect at about 10 feet agl. The engines seemed to be running, and no sputtering or smoke was observed. A hill dropped off past the end of the runway. The airplane came to rest upright about 30 yards into a flooded area, with the wings facing north and the fuselage canted about 30 degrees relative to the wings. The nose section was separated from the remainder of the fuselage, and the windshield was broken. Fuel was present at the accident site.
Engine Examination
Examination of the right engine revealed a lack of compression on the #4 cylinder. Further investigation found that the #4 cylinder intake valve spring was fractured into five pieces. Metallurgical examination indicated that some spring fracture surfaces had been damaged by mechanical contact, but undamaged surfaces exhibited features indicative of fatigue progression. The fatigue initiation was located at corrosion pits on the spring surface. Similar corrosion pits and red rust deposits were observed on many areas of the spring. The fatigue initiation also coincided with longitudinal tooling marks consistent with the original forming of the spring.
Aircraft Information
The accident airplane was a 1958 Beech model 95, serial number TD-14. It was powered by two Lycoming O-360-A1A engines, each rated at 180 horsepower. According to maintenance logs, an annual inspection was completed on October 15, 2009, at a total airframe time of 7,078.1 hours. The left engine (serial number L515-36) was overhauled in July 1990, and the right engine (serial number L2076-36) was overhauled in June 2008. At the time of the annual inspection, the left and right engines had accumulated 1,837.0 hours and 2.1 hours since overhaul, respectively. The pilot reported that at the time of the accident, the left and right engines had accumulated 1,940 hours and 18 hours since overhaul, respectively. A flight log for N20FP, covering January 7, 2010, through April 1, 2010, showed a total of 14.1 hours flown.