Daytona Beach, FL, USA
N375LP
CESSNA 172S
Upon reaching a cruise altitude of 3,000 feet, the engine began to run rough and make loud noises. The flight instructor assumed control of the airplane, and the engine subsequently lost all power. Oil was present on the windscreen. The instructor performed a forced landing in a nearby field where the nose gear contacted a ditch, resulting in a nose over and substantial damage to the airframe. Initial examination of the engine revealed a hole on the lower case and the camshaft partially protruding from the upper case. Suspecting a failure of the No. 4 piston, it and cylinder were subsequently examined; all fracture surfaces showed signs of overstress; however, there was no indication of preexisting mechanical damage that would have led to progressive failure, including fatigue. No corrosion or chemical degradation was found on the piston fracture surfaces. Accordingly, the initiating event that led to the catastrophic failure of the engine could not be determined.
On April 9, 2012, about 1325 eastern daylight time, a Cessna 172S, N375LP, was substantially damaged during a forced landing following a total loss of engine power near Daytona Beach, Florida. The flight instructor and commercial-rated student pilot were not injured. The airplane was registered to and operated by Air America Flight Center LLC under the provisions of 14 Code of Federal Regulations Part 91 as an instructional flight. Visual meteorological conditions prevailed and no flight plan was filed. The local flight originated at Daytona Beach International Airport (DAB), Daytona Beach, Florida, at 1310. According to the flight instructor, upon reaching a cruise altitude of 3,000 feet mean sea level, the engine began to run rough and several loud noises were heard. He assumed control of the airplane from the student and assessed the situation. The engine then lost all power, with zero oil pressure and rpm. Oil was visible of the windscreen. After securing the engine, the CFI set the aircraft up for a forced landing in a nearby field. After an uneventful landing, the landing gear contacted a ditch and the airplane nosed over. The flight instructor reported substantial damage to the wings, fuselage, and vertical stabilizer. An inspector with the Federal Aviation Administration (FAA) performed a cursory examination of the airframe and engine and reported that the engine case was ruptured and the camshaft was partially exposed. The engine was secured until a more detailed examination could be performed. On April 12, 2012, the FAA inspector performed a disassembly and inspection of the engine. A hole was evident in the lower engine case due to internal damage. The internal parts appeared to be well lubricated and there was no evidence of oil starvation. The camshaft was partially pushed through the case and fractured. He suspected a failure of the number four piston. He removed the piston and associated cylinder for further inspection by the NTSB. The engine had undergone about 222.5 flight hours since the last overhaul and 2965.1 hours since new. The engine was inspected 66.6 hours prior to the accident. Maintenance records revealed that the airplane was involved in a propeller strike and subsequent inspection on February 10, 2012. Staff from the NTSB Materials Laboratory examined the number four cylinder, piston fragments, and a variety of other engine fragments from the Lycoming IO-360-L2A air-cooled piston aircraft engine. Most of the adjacent components in the engine assembly experienced indications of buffeting and impact with other metallic components. The lower bore of the connecting rod was collapsed inward. The oil seal gasket appeared in serviceable condition with no indications of tears or cracks. The inside bore of the cylinder exhibited some rust-colored oxidation, primarily located in areas where the piston crown was in contact with the cylinder surface. The rust was consistent with corrosion from exposure to the environment after the initial failure. The piston crown was fractured from the connecting rod, embedding itself in an off-center direction inside the bore of the cylinder. The piston was removed from the cylinder and cleaned to remove debris and oil. The piston crown was fractured in several locations, but exhibited two primary fracture surfaces perpendicular to the crown face. Both fracture surfaces exhibited damage such as smearing consistent with material contact after the initial fracture. The undamaged areas of the fracture surfaces exhibited a darker luster than the smeared areas. These undamaged areas appeared dull and fibrous, except for small microscopic facets that reflected light. The fracture surfaces exhibited river patterns and tear ridges parallel to the crack direction, which moved from the rod side to the crown face of the piston. The fracture surfaces were inspected using a scanning electron microscope (SEM). Much of the fracture surface was obliterated by smearing, and isolated areas revealed dimple rupture. Dimple rupture is indicative of overstress failure. The morphology of the dimples observed was indicative of failure in tensile, shear, and mixed directions. The fracture surface exhibited areas of second phases high in silicon that had fractured from cleavage. This fracture surface morphology is common in high-silicon aluminum castings, which typically exhibit less ductility than aluminum forgings. Inspection of the chemical composition using energy dispersive X-ray spectroscopy revealed the piston material consistent with a high-silicon aluminum casting material. Lead-based particles were also found on the fracture surfaces; these particles were consistent with lead-based additives used in aviation fuel. There was no indication of preexisting mechanical damage that would have led to progressive failure such as fatigue. No corrosion or chemical degradation was found on the piston fracture surfaces.
A total loss of engine power due to a catastrophic engine failure, the origin of which could not be determined during postaccident examination.
Source: NTSB Aviation Accident Database
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