History of Flight
On April 3, 2009, at 1853 eastern daylight time, a Cirrus SR22, registration N509SR, executed a forced landing to a road in Northport, Florida, following an engine failure. The airplane sustained minor damage, and the certificated airline transport pilot and two passengers were not injured. Visual meteorological conditions prevailed. The flight was operated under 14 CFR Part 135 as an on-demand air taxi, on an instrument flight rules flight plan from Page Field (FMY) in Fort Myers to St. Petersburg-Clearwater International Airport (PIE). According to the pilot, about 10 minutes after takeoff, while level at 6,000 feet, engine oil pressure dropped to 28 psi. Approximately two minutes later, the engine began running rough and oil pressure decreased to 10 psi. Shortly after, the engine quit. The pilot performed a forced landing onto a road; during the landing rollout, the right wing struck a road sign. Flight data download showed the airplane took off about 1841, engine failed at 1850, and landing at 1853.
Aircraft Information
The airplane was powered by a Teledyne Continental Motors IO-550-N engine. Total engine time was 1,707.7 hours since new, with a build date of August 28, 2006. The most recent phase inspection was completed on March 30, 2009, at 1,695.5 hours. Maintenance records contained no indication that the number 6 connecting rod had been removed since the engine was new.
Wreckage and Impact Information
Examination revealed only minor damage to the right wing leading edge. The engine's upper deck was breached near the number 5 and number 6 cylinders. At the manufacturer's facilities under NTSB oversight, disassembly confirmed the crankcase breach. The crankshaft and counterweight assembly exhibited lubrication distress, thermal damage, and mechanical damage. The number 2 and 3 main bearings showed thermal discoloration. Connecting rods for cylinders 3, 5, and 6 had separated from the crankshaft journal. Bearings for rods 1 through 5 displayed thermal discoloration and damage. The number 6 connecting rod was bent below the pin bushing; its cap was distorted, and both cap bolts were fractured. The rod bearing had mechanical damage but no thermal distress. One cap bolt self-locking retaining nut was missing. Oil galleys and passages in both crankcase halves were clear and unrestricted.
Materials Laboratory Examination
With NTSB Materials Laboratory agreement, the number 6 connecting rod, piston, piston pin, and connecting rod bolts were submitted to the TCM materials laboratory. The laboratory factual report, reviewed by the NTSB Materials Laboratory Chief, indicated one bolt separated consistent with ductile overload below the splitline; its self-locking retaining nut remained in its original position. The other bolt's fracture surface exhibited extensive post-separation damage, occurring above the split line. Fretting adjacent to the bolt hole on the connecting rod split line face indicated the rod cap and rod had been separating and contacting for a period. That bolt also showed extensive thread damage. Hardness of each bolt and the one nut conformed to manufacturing requirements.