CEN12FA025

The pilots were about 5 miles from the destination airport when they heard a "loud bang" and engine oil immediately covered the front windshield. The engine continued to produce partial power until the airplane was in the airport traffic pattern, and then it lost total power. Due to a complete lack of forward visibility and another airplane in the runway run-up area, the flight instructor elected to make a forced landing on a roadway bordering the east side of the airport. The airplane struck a car and a pole before coming to a stop. A postaccident examination of the engine revealed that the number 2 connecting rod had separated from the crankshaft. The connecting rod failed about mid-length, with the upper portion remaining attached to the piston. The lower portion of the connecting rod was not recovered. The upper portion of the connecting rod and a recovered section of the rod cap both failed as a result of overstress bending. Neither component appeared discolored, which suggests there was an adequate engine oil supply before the failure. The number 1 and 3 connecting rods remained attached to the crankshaft; the number 4 connecting rod had separated from the crankshaft. The number 1, 3, and 4 connecting rods were discolored, consistent with continued operation with an insufficient supply of engine oil. Deformation of the lower end of the number 4 connecting rod was consistent with secondary mechanical damage; however, the rod appeared otherwise undeformed. A lack of evidence of oil starvation and the preponderance of crankcase damage in the area of the number 2 cylinder suggests that the engine failure was initiated by the separation of the number 2 connecting rod from the crankshaft. Metallurgical examination of the number 2 cylinder assembly and related components did not identify the initiating cause of this connecting rod separation. The total loss of engine power occurred upon separation of the number 4 connecting rod, which was precipitated by the prior loss of engine oil and secondary to the initial failure.

HISTORY OF FLIGHT On October 17, 2011, about 1400 central daylight time, a Piper PA-28R-200 (Arrow II) airplane, N300KR, was substantially damaged during a forced landing following a loss of engine power near the Watertown Municipal Airport (RYV), Watertown, Wisconsin. The flight instructor and pilot receiving instruction were not injured. The airplane was registered to and operated by Wisconsin Aviation – Four Lakes Inc. under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed for the flight, which was not operated on a flight plan. The local instructional flight departed from RYV about 1300. The flight crew reported that they were about 5 miles northwest of RYV at 4,000 feet mean sea level, when they heard a "loud bang" and oil immediately covered the front windshield. The flight instructor assumed control of the airplane and altered course for the airport. The engine continued to produce partial power; although, it subsequently lost power completely in the airport traffic pattern. The flight instructor immediately established a glide for runway 29. However, due to a complete lack of forward visibility and another airplane in the runway run-up area, he elected to execute a force landing to a roadway bordering the east side of the airport. The airplane struck a car and a pole before coming to a stop. The driver of the car was not injured. The airplane sustained substantial damage to the right wing. PERSONNEL INFORMATION The flight instructor held a commercial pilot certificate with single and multi-engine land airplane, and instrument airplane ratings. He held a current flight instructor certificate with single and multi-engine airplane, and instrument airplane ratings. He was issued a first class airman medical certificate on January 18, 2011, with a restriction for corrective lenses. He reported a total flight time of 4,900 hours, with 400 hours in Piper PA-28R-200 airplanes. The pilot receiving instruction held a private pilot certificate with a single-engine land airplane rating. He was issued a third class airman medical certificate on August 25, 2010, with restrictions for corrective lenses and flight at night. He reported a total flight time of 190 hours, with 5 hours in Piper PA-28R-200 airplanes. He was receiving instruction for a complex airplane endorsement at the time of the accident. AIRCRAFT INFORMATION The accident airplane was a Piper PA-28R-200, serial number 28R-7635210. It was a low wing, four place, single-engine airplane, with a retractable, tricycle landing gear configuration. The airplane was powered by a 200-horsepower Lycoming IO-360-C1C engine, serial number RL-14894-51A. It was a four cylinder, normally aspirated, reciprocating engine. Maintenance records indicated that an annual inspection was completed on May 24, 2011, at 7,021.2 hours total airframe time. At the time of that inspection, the engine had accumulated 2,851.9 hours, with 698.1 hours since overhaul. Theengine overhaul was completed in May 2005. The airplane had accumulated 81.2 hours since the annual inspection. The records indicated that an oil change was completed on September 1, 2011, at 7076.2 hours total airframe time, with no anomalies noted. There were no subsequent entries contained in the engine maintenance logbook. METEOROLOGICAL INFORMATION Weather conditions recorded by the RYV Automated Weather Observing System, at 1415, were: wind from 260 degrees at 13 knots, gusting to 19 knots; 10 miles visibility; clear sky; temperature 15 degrees Celsius; dew point -6 degrees Celsius; and altimeter 29.76 inches of mercury. WRECKAGE AND IMPACT INFORMATION The airplane came to rest on a roadway bordering the airport. The right wing exhibited leading edge impact damage near mid-span. One propeller blade was bent aft about 20 degrees over the outboard two-thirds of the blade span. That propeller blade exhibited nicks, spanwise scratches, and transfer marks over the length of the blade. The remaining two propeller blades appeared undamaged. The lower, right area of the engine cowling exhibited fiberglass delamination and paint cracking consistent with impact damage. The engine crankcase was fractured near the number 2 cylinder. The crankcase interior exhibited multiple gouges consistent with mechanical damage. The number 1 and 3 connecting rods remained attached to the crankshaft; the number 2 and 4 connecting rods had separated. The crankshaft and camshaft remained intact. However, the camshaft contained gouges consistent with secondary mechanical damage. The crankshaft was discolored in the vicinity of the number 1, 3 and 4 connecting rods consistent with oil starvation. The crankshaft was not discolored at the number 2 connecting rod journal. The oil sump and oil filter contained multiple metallic fragments. The number 2 connecting rod had failed about mid-length and the upper portion remained attached to the piston. The lower portion of the rod was not recovered; although, a portion of the corresponding rod cap and an entrapped bolt fragment were recovered. The remaining rod bolt was not recovered. The rod cap was deformed consistent with secondary mechanical damage. The number 2 piston was retained within the cylinder bore. The piston exhibited impact dents and gouges on the lower portion, but appeared to be otherwise undamaged. The connecting rod and rod cap section did not appear to be discolored. The number 4 connecting rod remained attached to the piston and the full length of the rod remained intact. The piston appeared intact. The lower end of the connecting rod and the separated rod cap were discolored and deformed, consistent with both oil starvation and secondary mechanical damage. TESTS AND RESEARCH Metallurgical examination of the number 2 connecting rod revealed features consistent with overstress bending separation. The rod cap section recovered exhibited features indicative of bending overstress with no indication ofprogressive cracking. The entrapped rod cap bolt displayed features consistent with tension overstress fracture.