Accident Overview
On September 29, 2015, about 1100 central daylight time, a Piper PA-28RT-201T, registration N2175K, operated by a private individual, was substantially damaged during a forced landing to a field near Dawson Springs, Kentucky. The private pilot was seriously injured. The personal flight, operating under 14 Code of Federal Regulations Part 91, originated from Foley Municipal Airport (5R4), Foley, Alabama, about 0730, with a planned destination of Owensboro Airport (OWB), Owensboro, Kentucky. Visual meteorological conditions prevailed, and an instrument flight rules flight plan had been filed.
Engine Failure Event
According to the pilot, while in cruise flight at 7,000 feet mean sea level (msl), a loud bang was heard and the engine began to run rough. The pilot declared an emergency to air traffic control (ATC). Subsequently, another bang was heard, and the engine lost all power. Pieces of the engine exited the cowling, and oil flowed onto the windscreen. With ATC assistance, the pilot attempted to divert to runway 36 at Tradewater Airport (8M7) in Dawson Springs, Kentucky. However, after descending through a cloud layer at 1,800 feet msl, the pilot could not locate the turf runway and elected to perform a forced landing to a field.
Wreckage and Engine Examination
Examination of the wreckage by a Federal Aviation Administration (FAA) inspector revealed that the airplane came to rest upright against a small tree in a field about 1 mile west of 8M7. Damage was observed to both wings and the fuselage. The airplane was equipped with a Continental Motors TSIO-360 engine. A hole was found in the top rear of the engine crankcase near the No. 2 cylinder. Subsequent teardown examination of the engine revealed that a rear crankshaft counterweight had separated, and the adjacent (No. 2) connecting rod also separated at the connecting rod bolts. Metallurgical examination of the counterweight showed fatigue cracking originating at the counterweight aft blade surface near a bushing hole. Marks on the bushing hole were consistent with loose bushing movement over a period of time.
Maintenance History
Review of maintenance records and information provided by the pilot indicated that the engine had been operated for about 80 hours since its most recent annual inspection, completed on November 4, 2014. At that time, the engine had accumulated 1,049 hours since its last overhaul, which was completed on January 4, 1997. Continental Motors service bulletin M93-4 provided information about crankshaft counterweights at overhaul and included warnings about improper installation of bushings, retaining plates, or retaining rings leading to engine failure. Additionally, Continental Motors published a service information letter (SIL) recommending time limits between major overhauls of 1,800 hours of operation or 12 years, whichever occurred first, for the make and model engine.
Weather Conditions
Madisonville Regional Airport (2I0), Madisonville, Kentucky, located about 16 miles northeast of the accident site, recorded weather at 1055 as: wind from 100 degrees at 4 knots; visibility 5 miles in light rain; scattered clouds at 1,900 feet; broken ceiling at 3,700 feet; overcast ceiling at 4,400 feet; temperature 22 degrees C; dew point 22 degrees C; altimeter 29.90 inches of mercury.