Accident Overview
On September 30, 2016, about 1430 central daylight time, a Cessna 177RG, registered as N1528H, experienced a loss of engine power during cruise flight, necessitating a forced landing near Cloquet, Minnesota. The pilot, who was the sole occupant, was not injured. The airplane sustained substantial damage to the aft fuselage during the landing. The flight was operated under 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and no flight plan was filed.
The flight originated from Cook Municipal Airport (CQM) in Cook, Minnesota, at about 1300, with a destination of Field of Dreams Airport (04W) near Hinckley, Minnesota. While in cruise, the pilot detected a slight ticking sound from the engine. He checked the oil pressure gauge and found the indication just below the green arc but above the critical red line. He decided to divert to Cloquet/Carlton County Airport (COQ) in Cloquet to inspect the engine. As the airplane approached COQ, the engine noise grew louder, and oil pressure continued to drop. About 5 miles from COQ, oil pressure fell below the red line, and the engine began knocking loudly. Approximately 3 miles from COQ, the engine stopped, and the propeller ceased windmilling. The pilot attempted to glide to the runway but was unable to reach it, landing in a field short of runway 17. The landing was smooth, but during rollout, the airplane entered a roadside ditch, resulting in structural damage.
Engine Examination
The airplane was powered by a Lycoming IO-360-A1B6D engine (serial number L-18530-51A) rated at 200 horsepower. National Transportation Safety Board and Federal Aviation Administration investigators conducted a partial teardown examination. A fracture was found in the engine case above the No. 4 cylinder, with a portion of the No. 4 connecting rod visible. A crack was also noted in the accessory case behind the No. 4 cylinder. The engine contained about 5.5 quarts of oil. Examination of the rocker covers revealed no anomalies in rocker arms, valve springs, or push rod ends. The rear accessories and accessory case were removed, and gear train continuity was confirmed.
The No. 1, 3, and 4 cylinders were removed; the No. 2 cylinder could not be fully removed due to a damaged cylinder skirt. The No. 4 connecting rod remained attached to its piston, with the large end fractured adjacent to the rod cap bolt holes. Portions of the connecting rod and rod cap were found in the oil sump. The large end exhibited discoloration consistent with heat distress. The No. 1 cylinder, piston, and connecting rod were intact, but the connecting rod could not rotate on the crankshaft; the No. 1 bearing was extruding, indicating imminent failure. The No. 3 cylinder assembly was intact, and the No. 3 bearing showed signatures consistent with a lack of lubrication. The No. 2 cylinder assembly was intact.
The oil pressure relief valve was disassembled with no anomalies. The oil screen was plugged with debris, but it could not be determined if the debris was secondary to the failure. The oil pump and remainder of the oil system showed no anomalies.
Maintenance History
A review of the airplane's maintenance records indicated that the most recent annual inspection was completed on January 27, 2016, at a recording tachometer reading of 4,250.8 hours. A 100-hour inspection of the engine was performed on the same date. At that time, the engine had accumulated 1,320.56 hours since its most recent overhaul, which was completed on April 26, 1993. The engine was installed on the accident airplane on June 4, 1993. The recording tachometer read 4,278.4 hours postaccident, indicating 27.6 hours since the annual/100-hour inspection. Engine oil and filter were changed on April 19, 2016, at a tachometer reading of 4,259.22 hours.
Lycoming Service Instruction 1009AT recommended that engines not accumulating the specified overhaul time within twelve years be overhauled due to potential deterioration. The recommended time between overhauls for the accident engine was 2,000 hours.