History of the Flight
On October 12, 2014, at about 1250 eastern daylight time, a Cessna 180K, registration N2590K, experienced a loss of engine power and subsequently nosed over during a forced landing in Boca Raton, Florida. The private pilot sustained minor injuries, while the passenger was uninjured. The flight had departed Columbus Airport (CSG), Columbus, Georgia, around 0930, destined for Boca Raton Airport (BCT), Boca Raton, Florida. Visual meteorological conditions prevailed, and an IFR flight plan was filed for the personal flight conducted under 14 CFR Part 91.
According to the pilot, the day before the accident, he and his wife departed Southwest Michigan Regional Airport (BEH), Benton Harbor, Michigan, at approximately 1015, flew about 1.5 hours to Monroe County Airport (BMG), Bloomington, Indiana, for fuel. After landing at BMG, they had the airplane refueled with 24 gallons and then departed for CSG. After 3.2 hours of flight, they landed at CSG, where the pilot had the airplane refueled again, topping off the tanks with 54.3 gallons, and then checked into a hotel.
The following morning, the pilot and his wife returned to CSG and departed for BCT at about 0930. The pilot reported that the flight was pleasant with some clouds and buildup near Sebring, Florida, and that he entered and flew in instrument meteorological conditions for about 42 minutes at a cruising altitude of 5,000 feet mean sea level (msl) without issues. As they were handed off to Palm Beach Approach, they descended to 4,000 feet msl, then gradually to 2,000 feet msl. After leveling at 2,000 feet, they were cleared to 1,000 feet msl and handed off to BCT control tower. Moments later, the airplane began shaking violently, a loud noise was heard, and the propeller stopped rotating, then began windmilling slowly. The engine would not produce any power. The tower cleared them for a visual approach to runway 05.
The pilot realized they would not reach the airport, so he and his wife began looking for an undeveloped area for an engine-out landing while he trimmed the airplane and attempted to restart the engine. He spotted a former polo field being developed into home sites and turned toward it, considering it the only chance for an unobstructed landing. His wife spotted wires and advised him while he continued flying and attempting restart. After clearing the wires, he turned to align with the polo field and landed. The ground was soft and sandy; during the landing roll, the airplane nosed over and came to rest inverted. The pilot and his wife released their safety harnesses and egressed.
Aircraft Information
The airplane was a 4-place, single-engine, high-wing monoplane of conventional metal construction, equipped with tailwheel landing gear. It was powered by a normally aspirated, 285-horsepower, air-cooled, horizontally opposed, direct-drive engine driving a three-bladed Hartzell controllable-pitch propeller. According to FAA airworthiness records, the engine had been converted from a fuel-injected Continental IO-550-F to an O-550-F/TS by Texas Skyways Incorporated under STC, which involved removing the fuel-injection system, replacing 8.5:1 compression pistons with 7.5:1 pistons, and installing a carburetor. The STC applied to Cessna 180s and 182s manufactured from 1953 through 1986. The airplane was manufactured in 1978.
The engine's most recent major component replacement was on March 21, 2012, at 983.53 hours of operation (46.16 hours prior to the most recent annual inspection), involving removal, overhaul, and reinstallation of the No. 3 and No. 4 cylinder assemblies. The most recent annual inspection was completed on December 1, 2013, at which time the airplane had 4,545.74 total hours and the engine had 1,096.43 total hours.
Meteorological Information
The recorded weather at BCT, located 3 nautical miles northwest of the accident site, at 1153 included winds 090 at 10 knots, 10 miles visibility, scattered clouds at 2,500 feet, temperature 30°C, dew point 23°C, and an altimeter setting of 30.06 inches of mercury.
Wreckage and Impact Information
Examination of the airplane revealed substantial damage. The engine cowling was bent and dented. One propeller blade was bent aft about 15°, and a second blade had a visible bend about 12 inches outboard of the blade clamp. The left lift strut was bent at a 20° angle near midspan, and the left aileron was bent in two places. The upper surface of the left wing displayed wrinkling forward of the wing flap and at the leading edge forward of the fence. The tops of the vertical stabilizer and rudder were crushed.
The engine remained intact with no impact damage. The crankshaft was intact externally; the crankcase had a very small crack near a backbone bolt. All rear accessories were attached and undamaged. The exhaust and induction systems showed normal operating signatures. Both magnetos produced spark on all six posts on the test bench. The ignition harness was intact. All spark plugs displayed normal operating signatures; No. 5 and No. 6 top spark plugs were Autolite, others Champion. The carburetor was undamaged with a clear fuel inlet screen. The oil sump contained multiple metallic components and particles consistent with bearing material, piston material, one counterweight pin retaining plate, and one snap ring. The oil pick-up tube and screen had a small amount of metallic particles. The oil pump housing displayed scoring consistent with hard particle passage. The oil filter pleats contained significant metallic material. All six cylinders remained attached; detailed examination revealed anomalies including a loose hold-down nut on No. 1 cylinder, corrosion and mechanical damage on No. 2 cylinder piston, blue staining on No. 6 cylinder, and a small valve strike indentation on No. 6 piston. The crankcase displayed mechanical damage in multiple locations, including a No. 2 bearing support damage consistent with a bearing shift and spun bearing event. The crankshaft was fractured between the No. 2 main journal and No. 2 connecting rod journal; a crack was also found along the bend radius of the No. 1 journal via magnaflux. A counterweight leading edge pin was loose in the crankcase. Connecting rod bearings showed signs of lubrication distress on No. 2, No. 4, and incipient distress on No. 2.
Tests and Research
Continental Motors Service Bulletin SB03-3 advises that cylinder removal should not be done unless a borescope inspection reveals a definite problem. The engine's cylinder installation process involves a multiple-step torque procedure to maintain proper main bearing crush. Service Bulletin SB96-7C warns that failure to torque through bolt nuts on both sides of the engine can result in a loss of main bearing crush with main bearing shift and subsequent engine failure.
The investigation did not identify a specific cause for the engine failure, but the mechanical damage observed in the engine was consistent with a loss of lubrication leading to a catastrophic failure.