History of Flight
On May 23, 2008, about 1150 mountain standard time, a Cessna P210N, registration N4753K, experienced a total loss of engine power during cruise flight near Peach Springs, Arizona. The airplane subsequently collided with terrain during the forced landing. The certificated private pilot, who was also the owner, was not injured. The airplane sustained substantial damage to both wings due to impact forces.
The cross-country personal flight departed Grand Canyon National Park Airport, Grand Canyon, Arizona, about 1100, with a planned destination of Bullhead City, Arizona. Visual meteorological conditions prevailed, and an instrument flight rules flight plan had been filed.
The pilot reported that while flying at 16,000 feet mean sea level, the engine experienced a total loss of power. He informed air traffic control that he intended to land at Grand Canyon Caverns Airport (L37), about 12 miles from his position. The pilot was unable to reach the airport. During the landing attempt on desert terrain, one of the main landing gear wheels struck a cactus, causing the airplane to nosed over.
During recovery, internal engine components were observed in the debris field. The airplane was recovered for further examination.
Aircraft Information
The airplane was a 1979 Cessna P210N, serial number 21000284. At the last annual inspection, the total airframe time was 2,950 hours. The logbooks contained an entry for the annual inspection dated October 4, 2007, with a tachometer reading of 1,483.6 hours. At the accident site, the tachometer read 1,519.6 hours.
The engine was a Teledyne Continental Motors TSIO-520-P5B, serial number 278661-R. Total time on the engine at the last annual inspection was 978 hours since major overhaul.
On March 21, 2007, a field top overhaul was completed, which included removing all six cylinders, overhauling them, and reinstalling them on the engine. The tachometer reading at that time was 1,399.2 hours. The engine failure occurred 120 hours after that overhaul.
Engine Examination
During the engine teardown inspection, thermal discoloration was noted on the main journals of the crankshaft, and damage was observed on the counterweight hanger blade. The crankshaft had separated forward of the number two main journal, and the number two main bearing was not found. The Safety Board decided to continue the inspection at the TCM Analytical Department in Mobile, Alabama.
Further inspection revealed that the crankshaft exhibited a fracture just forward of the number 2 main bearing journal. The crankshaft main bearings and connecting rod bearings showed signatures of lubrication distress. The number 2 main bearing support exhibited signatures of bearing shift, tang slot elongation, and rotation. The crankcase had an approximate 4- by 6-inch breach above both the number 3 and number 4 cylinders.
The crankshaft fracture was sectioned and forwarded to the TCM Metallurgical Laboratory for examination on December 12, 2008.
Hardness at the journal surface measured 70R30N, meeting specification. A sectioned piece perpendicular to the surface showed a case depth of 0.020 inches and a core hardness of 35 HRC, both meeting specification. The fracture surface indicated that the fracture initiated at the surface adjacent to the number 2 main bearing and progressed toward the number 3 rod journal in fatigue. Much of the fracture surface was damaged, presumably due to continued operation during and after separation.