ERA09FA228

About 10 minutes after takeoff, when the airplane was in level cruise flight, the engine lost power. The pilot performed a forced landing to a road, which resulted in minor damage to the airplane when the right wing impacted a road sign. An initial examination of the engine revealed a hole in the upper deck in the vicinity of the Nos. 5 and 6 pistons. Further examination revealed that both of the No. 6 connecting rod bolts were fractured. One bolt was missing the self-locking nut, and fretting adjacent to the bolt hole on the split-line face of the connecting rod indicates that the bolt was probably not tightened with sufficient torque and backed off the bolt. The bolt then likely backed out of its hole on the connecting rod, enabling the cap to hinge open, and the loading of the other bolt in tension and bending to the point of overstress. The connecting rod then separated from the crankshaft and punched a hole in the crankcase.

HISTORY OF FLIGHT On April 3, 2009, at 1853 eastern daylight time, a Cirrus SR22, N509SR, incurred minor damage during a forced landing, following an engine failure, in Northport, Florida. The certificated airline transport pilot and the two passengers were not injured. Visual meteorological conditions prevailed. The airplane was operating on an instrument flight rules flight plan from Page Field (FMY), Fort Myers, Florida, to St. Petersburg-Clearwater International Airport (PIE), St. Petersburg, Florida. The on-demand air taxi flight was conducted under the provisions of 14 Code of Federal Regulations Part 135. According to the pilot, about 10 minutes after takeoff, when the airplane was level at 6,000 feet, he noticed that the engine oil pressure had dropped to about 28 psi. About 2 minutes later, the engine began to run "real rough," and the oil pressure dropped to 10 psi. Shortly after that, the engine quit, and the pilot performed a forced landing to a road. During the landing rollout, the right wing hit a road sign. A download of flight data revealed that the airplane took off about 1841; at 1850, the engine failed; and at 1853, the airplane landed. AIRCRAFT INFORMATION The airplane was powered by a Teledyne Continental Motors (TCM) IO-550-N engine. According to maintenance records, total engine time was 1,707.7 hours since new. The build date was August 28, 2006. The latest phase inspection was completed on March 30, 2009, at 1,695.5 hours since new. There was no indication in the maintenance records that the number 6 connecting rod had been removed since the engine was new. WRECKAGE AND IMPACT INFORMATION An examination of the airplane revealed only minor damage to the right wing leading edge. An initial examination of the engine revealed that the upper deck was breached in the vicinity of the number 5 and number 6 cylinder positions. The engine was subsequently disassembled and examined under NTSB oversight at the manufacturer's facilities. Examination confirmed that the crankcase was breached above the number 5 and number 6 cylinder positions. The crankshaft and counterweight assembly exhibited lubrication distress, thermal damage, and mechanical damage. The number 2 and number 3 crankshaft main bearings exhibited thermal discoloration. The number 3, 5 and 6 connecting rods were separated from the crankshaft journal, and the number 1 through 5 connecting rod bearings exhibited thermal discoloration and damage. The number 6 connecting rod exhibited mechanical damage and was bent below the pin bushing. The connecting rod cap was distorted, and both cap bolts were fractured. The connecting rod bearing exhibited some mechanical damage, but no sign of thermal distress. One of the cap bolt self locking retaining nuts was missing. The oil galleys and passages in the left and right crankcase halves were clear and unrestricted. With agreement from the NTSB Materials Laboratory, the number 6 connecting rod, piston, piston pin, and connecting rodbolts were submitted to the TCM materials laboratory (M&P Laboratory) for analysis. According to the laboratory factual report, which was reviewed by the Chief, NTSB Materials Laboratory, one bolt exhibited separation consistent with ductile overload below the splitline location. The self locking retaining nut was still in its original position on the bolt. The fracture surface of the other bolt exhibited "extensive" post-separation damage to the fracture surface, which occurred above the split line location on the bolt. There was fretting adjacent to the bolt hole on the split line face of the connecting rod, indicating that the rod cap and rod were separating and hitting for a period of time. The bolt also showed "extensive" thread damage. The hardness of each bolt and the one nut conformed to the manufacturing requirements.