Bend, OR, USA
N199L
MKII Corporation Lancair Legacy 2000
While at 9,000 feet, the engine lost oil pressure, suddenly oversped (3,560 rpm), and lost power. The pilot made a dead-stick approach to a nearby runway. During the landing flare the airplane's main landing gear impacted a trench and sheared off just short of the runway. The airplane slid down the runway on its nose gear, main mount struts, and tail. The airplane then veered off to the right and departed the runway. Examination of the engine revealed a 4- to 5-inch diameter hole in the top of the engine case above the No. 3 cylinder. Further examination revealed that the No. 3 connecting rod of the engine had failed due to fatigue just below the wrist pin. The loose end of the connecting rod produced metal shavings that obstructed the oil pickup tube as the crankshaft continued to rotate. The blocked tube led to oil starvation, propeller overspeed, and catastrophic engine failure. Material Laboratory testing revealed that the connecting rod fatigue fracture was located in a decarburized region of the rod. The engine manufacturer could not identify the connecting rod as a component supplied by them.
On June 8, 2008, at 1709 Pacific daylight time, a MKII Corporation Lancair Legacy 2000, N199L, experienced a loss of engine power and the pilot executed a forced landing to Bend Municipal Airport, Bend, Oregon. Lancair International Incorporated operated the airplane under the provisions of Title 14 Code of Federal Regulations Part 91. The airline transport pilot and single passenger were not injured, and the airplane was substantially damaged. Visual meteorological conditions prevailed, and no flight plan had been filed. The flight originated at Marysville, California, about 1400. The pilot reported to the Safety Board investigator that while cruising at 9,000 feet, the engine suddenly oversped and quit. The failure was accompanied by a loud noise, heavy vibration, and smoke. The pilot immediately secured the engine, turned the fuel selector to off, and diverted to the nearest airport. He attempted to restart the engine but shut it down after observing heavy smoke. He made a dead stick approach to runway 34 at Bend Municipal Airport. During the landing flare the airplane's main landing gear impacted a trench and sheared off just short of the runway. The airplane slid down the runway on its nose gear, main mount struts, and tail. The airplane then veered off to the right and departed the runway. Examination of the engine revealed a 4- to 5-inch diameter hole in the top of the engine case above the number 3 cylinder. The engine logbook documented that the experimental Continental IO-550-FI-EXP was installed on the airplane November 12, 2006, with a time since overhaul (TSOH) of 0.0 hours. On August 1, 2007, the engine was reinstalled on the airplane after it had been overhauled by AvWorks Custom Engines & Components, and designated IO-550-L2-X, serial number 0813. An annual inspection was performed on June 1, 2008, at TSOH of 236 hours. The airplane was equipped with an Electronics International MVP-50P Flight Data Recorder. Engine data indicated a drop in oil pressure at 1606:00, followed by sudden engine rpm rise from 2,520 to 3,560, at 1606:14. On June 16, 2008, the engine was examined at the Lancair facility, Bend, by a Federal Aviation Administration inspector and a technical representative of Teledyne Continental Motors (TCM). The crankcase was missing a portion of the material above the number two, three, and four cylinder deck areas. The internal surfaces of the cylinder bays all exhibited mechanical related damage. Metal shavings were identified obstructing the oil pickup tube and screen. Following the inspection, the engine was shipped to the TCM factory, Mobile, Alabama, for further examination under the supervision of the Safety Board investigator-in-charge (IIC). On December 2, 2008, the engine was laid out and examined by investigators at the TCM Factory. Two halves of the number 3 cylinder connecting rod exhibited fracture signatures consistent with fatigue, and were sent to the Safety Board Materials Laboratory for detailed examination. The Materials Laboratory determined that the fracture surfaces on the crank shaft portion of the number 3 connecting rod sustained mechanical damage consistent with continued crankshaft rotation after the fracture. The wrist pin portion of the connecting rod was protected by the piston skirts, and the fracture surface was preserved. Stereomicroscope examination of the fracture surfaces indicated that the number 3 connecting rod failed due to tensile or single-sided bending fatigue. Numerous ratchet marks indicated that multiple fatigue cracks initiated at the surfaces of both rails of the I beam before growing together and independently progressing into the I beam cross sections. The two fatigue cracks covered about 60 percent of the connecting rod cross section, before the section failed due to mechanical over stress. Micrograph images of the rail surfaces in the immediate vicinity of the fatigue initiation points on the number 3 connecting rod rails indicated no grinding marks or unusual surface features. The roughness in the region appeared to be consistent with a shot peened surface, consistent with TCM specifications. A metallurgical section through the fatigue region of the connecting rod was examined. Metallographic analysis indicated that scale was embedded in the surface of the connecting rod to a depth of approximately 0.001-inch. Metallographic analysis also indicated that the surface of the connecting rod, in the vicinity of the fatigue fracture initiation site, had about 0.015-inch of total decarburization. Discussions with a representative from TCM revealed the connecting rod surface should not have any embedded scale in critical areas and should have no more than about 0.002-inch of decarburization. Representatives from TCM did not recognize the markings on the number 3 connecting rod and could not positively identify it as a TCM supplied part. The entire Materials Laboratory Factual Report is located in the official docket of this accident investigation.
A total loss of engine power due to the fatigue failure of the Number 3 cylinder connecting rod.
Source: NTSB Aviation Accident Database
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