20050517012609A

(-23) On may 17, 2005, at approximately 1013 EDT, a KR2, an amateur built experimental aircraft, N1701L crash landed approximately six miles east of Vienna, Georgia on Georgia highway 215. The crash location was N32.04.567' latitude and W083.41.455' longitude, and 464 feet above sea level, as determined by global positioning system (GPS). The pilot stated that the CFR 91 flight originated in atlanta, Georgia at the cobb county - mccollum field airport (ryy) and was enroute to the valdosta regional airport, at valdosta, Georgia (vld). The pilot stated that while in level cruise flight at 3,500 feet mean sea level (MSL) and east of Vienna, Georgia the engine lost power and simultaneously developed a severe vibration. The pilot shutdown the engine and said he was unable to make a crop dusting strip to the west and elected to land on the highway. The aircraft was on a westerly heading and aligned with the road and just below the tree tops the pilot stated that the aircraft was descending and landed very hard on the roadway, collapsing the right main landing gear in a forward direction. The aircraft then veered off the paved surface and the left main landing gear was sheared completely from the aircraft and the nose section impacted the ground and the aircraft rotated 180 degrees to the left and came to rest on a easterly heading. During the crash sequence the right wing aft spar was fractured. The aircraft was intact with the exception of the main landing gears. The weather conditions as reported at macon, Georgia were kmcn 171353Z 00000KT 10SM clr 22/13/A3000. An examination of the aircraft revealed that control continuity was available to all control surfaces. The left wing fuel tank holds approximately four gallons, and was nearly full, the right wing fuel tank did not have any visible fuel, and the main header fuel tank holds approximately 15 gallons and appeared to have approximately 13 gallons of fuel remaining. All flight and engine instruments were in a static position and indicating what would be expected at engine shutdown. The throttle was closed and the mixture was in the cut-off position. All switches were off except the master avionics and the handheld VHF communication radio and the GPS receiver, which were on and operating on internal battery power. A check of the oil quantity in the engine revealed the oil level to the approximately between fulland one quart low. An examination of the engine revealed the crankshaft was broken just behind the front main bearing before the crankshaft exits the engine and attaches to the propeller. The crankshaft has an extension between it and the propeller in order for the propeller to clear the cowling. A review of the maintenance records show that the aircraft had a condition inspection conducted on March 13, 2005 by the pilot/owner who holds a repairman certificate. On may 05, 2005 there is a maintenance record entry indicating that the prop extension was found to be out of true, and the shaft, prop, and spinner combo were balanced. At the accident site it was observed that washers were affixed to the back of the propeller spinner in order to balance the shaft, propeller, and spinner combo. The pilot stated that after this was accomplished there was a marked smoothness in the engine/propeller operation. Approximately 8.2 hours after the shaft, propeller, and spinner combo was balanced the crankshaft broke. Examination of the propeller spinner revealed voids in the fiberglass which could explain some of the out of balance condition. Additionally, the fact that an extension was used between the crankshaft and the propeller and it was found to be out of true probably contributed to the vibration. The extension caused a wobble and placed an undue strain on the crankshaft over a period of time causing the crankshaft to fail. At the time of the aircraft accident there was approximately 154.4 hours on the corvair engine since installation. If an extension between the crankshaft and the propeller was not used or if it was in true and balanced on this installation it is believed that this accident would not have occurred.