Clear, AK, USA
N42DC
Helio H-295
The certificated airline transport pilot reported that while in level, cruise flight, the engine began to run rough and lose power. The pilot said that while performing the engine emergency procedures, he smelled smoke in the cabin, and noted a substantial amount of engine oil on the windscreen. The airplane collided with trees during a subsequent forced landing. A postaccident investigation revealed that the number two connecting rod had sustained a complete fracture. The number 2 connecting rod journal displayed significant amount of heat induced bluing. The fractured connecting rod, main journal bearing shells (7 halves), and rod bearing shells (7 halves) were sent to the NTSB's Materials Laboratory for examination. A Senior Safety Board metallurgist reported that the separated connecting rod displayed evidence of low cycle, high stress fatigue cracking. A scanning electron microscope (SEM) examination of the rod bearing shells disclosed pitting, with irregular-shape metal particles embedded on the surface of the bearing material. The area around the pits showed evidence of metallic flow from the pits.
On March 3, 2001, about 1300 Alaska standard time, a wheel/ski equipped Helio H-295 airplane, N42DC, sustained substantial damage during a forced landing about 20 miles south of Clear, Alaska. The airplane was being operated as a visual flight rules (VFR) positioning flight under Title 14, CFR Part 91, when the accident occurred. The airplane was registered to, and operated by, Wright Air Service, Inc., Fairbanks, Alaska. The solo airline transport pilot was not injured. Visual meteorological conditions prevailed, and a VFR flight plan was filed. The flight originated about 1245, from the Stampede Airstrip, located about 37 miles west of Healy, Alaska, and was en route to Fairbanks. During a telephone conversation with the National Transportation Safety Board investigator-in-charge on March 5, the pilot reported that while in level, cruise flight, the engine began to run rough and lose power. The pilot said that while performing the engine emergency procedures, he smelled smoke in the cabin, and noted a substantial amount of engine oil on the windscreen. The airplane collided with trees during a subsequent forced landing, and sustained substantial damage to the wings, fuselage, and empennage. The pilot stated that a postaccident inspection revealed a fist-sized hole on the left side of the engine crankcase. The director of maintenance for the operator reported that at the time of the accident, the engine had accrued a total time in service of 1,143.0 hours since overhaul, and was installed in the accident airplane in late August of 1999. The engine maintenance records note that the engine was "overhauled" and reassembled per Lycoming overhaul manual 60294-5-6 on August 17, 1999. All work was performed by the operator, at the operator's maintenance facility, in Fairbanks. The airplane was eventually recovered by the operator and insurance personnel, and moved to the operator's maintenance facility in Fairbanks. On April 12, 2001, in the presence of a Federal Aviation Administration (FAA) airworthiness inspector from the Fairbanks Flight Standards District Office, an engine tear down and inspection was conducted at the operator's maintenance facility in Fairbanks. According to the FAA inspector, the inspection revealed that the number two connecting rod had sustained a complete fracture. The fracture surfaces displayed postfailure circumferential scoring, and damage. In addition, the FAA inspector noted a significant amount of heat induced, bluing of the number 2 connecting rod journal. The fractured connecting rod, main journal bearing shells (7 halves), and rod bearing shells (7 halves) were sent to the National Transportation Safety Board's Materials Laboratory for examination. A Senior Safety Board metallurgist reported that the separated connecting rod displayed evidence of low cycle, high stress fatigue cracking. He noted that a scanning electron microscope (SEM) examination of the rod bearing shells disclosed irregular-shape metal particles that were embedded on the surface of the bearing material. He added that the rod bearing shells displayed many pits. The area around the pits showed evidence of metallic flow from the pits.
The shifting of engine connecting rod bearings, and the fracture of an engine connecting rod.
Source: NTSB Aviation Accident Database
Aviation Accidents App
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