Edisto Island, SC, USA
N475RT
PIPER PA-32-300
Shortly after takeoff the engine started to “sputter,” then stopped producing power; oil then blew out of the engine cowling onto the windshield. The pilot made a forced landing in a field and the airplane contacted a wire fence, resulting in substantial damage to the airframe. A postaccident inspection of the engine revealed that the engine crankcase was ruptured in two places near the Nos. 5 and 6 cylinders. Subsequent detailed examinations showed the Nos. 5 and 6 connecting rods were fractured and that a counterweight retaining ring (circlip) was missing its eyelets and had separated from the counterweight assembly. Additional metallurgical examination revealed that the counterweight retaining ring failed due to fatigue. The failure allowed the counterweight roller to eject from the counterweight. Additionally, the No. 6 connecting rod exhibited evidence of a fatigue failure in multiple locations and the Nos. 5 and 6 pistons showed evidence of detonation. It is likely that the fatigue failure of the retaining ring or the fatigue failure of the No. 6 connecting rod occurred and propagated throughout the engine until a catastrophic failure resulted. The failure sequence could not be determined, but it is likely that the piston detonation exacerbated the process.
On January 11, 2022, about 1247 eastern standard time (EST), a Piper, PA-32-300, N475RT, was substantially damaged when it was involved in an accident near Edisto Island, South Carolina. The private pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, who was also the owner of the airplane, the first leg of the flight was uneventful. After landing at Columbus County Municipal Airport (CPC), Whiteville, North Carolina to get fuel, he resumed the flight to Florida. After departure, about 15 minutes into the flight, while cruising at 4,500 ft mean sea level, the engine started to sputter, then stopped, followed immediately by oil coming out of the engine cowling onto the windshield, partially limiting his field of view. Seeing no immediate landing location ahead of him, the pilot maintained 100 mph, turned 180° and declared an emergency. The pilot observed a straight road between two fields out of his side window and proceeded towards the area. After setting up for a short final to the road, he observed an electrified livestock fence on both sides of the road, but he was already committed for landing and was unable to avoid the fence. After touching down, both wings struck the fence. The airplane veered to the right traveled through the fence, and into a field for about 300 ft before coming to rest. The airplane came to rest upright. The right wing contained a large tear in the leading edge and the right landing gear collapsed. Closer examination of the engine revealed oil spray and a hole located on top of the No. 6 cylinder. The airplane was transported to a secured facility and the engine, and its components were subsequently examined. One propeller blade was twisted with its blade tip torn off. The other blade was bent aft about mid span. The propeller governor remained attached to the engine. The propeller governor gasket was found free of debris. All other components were free of preimpact or anomalous damage. All the spark plugs appeared slightly dark in color but were otherwise considered normal wear in accordance with the Champion Aviation Check-A-Plug chart. Two holes were found at the rear of the engine above the Nos. 5 and 6 connecting rods, exposing the camshaft. Crankshaft continuity could not be established because of internal damage that prevented movement. Upon disassembly, the Nos. 5 and 6 connecting rods were found broken at the connecting rod caps with no heat signatures present. One connecting rod cap bolt remained intact (bent) with visible threads and a missing nut. Both connecting rod caps were broken into pieces. Minor scoring was noted on the adjacent bearings and surfaces. The engine oil pump also showed minor scoring on the pump housing and there was ferrous material located in the pleats of the oil filter. The Nos. 5 and 6 piston crowns and cylinder head domes exhibited features consistent with detonation. The piston crowns were smooth and clean and had the appearance of being sandblasted with the compression and oil rings compressed into the ring walls. The internal retaining ring (circlip), washer, and roller were found separated from one of the counterweights. All of the internal retaining rings exhibited anomalous damage; their eyelets were broken off. One of the counterweight circlips had features consistent with fatigue and subsequent failure. The failed circlip corresponded to a counterweight roller that was ejected from the counterweight assembly. In addition, the No. 6 connecting rod showed evidence of fatigue failure in multiple areas. The areas showing fatigue were located on the main body of the rod and on the cap, along the bearing surfaces in the area where the connecting rod bolt joined them together, and where the I-beam of the rod transitioned to the bearing end of the rod. In addition, the Nos. 5 and 6 piston crowns, valve faces, and cylinder head domes were clean and free of combustion residue. The engine had accrued about 555 hours since overhaul by the manufacturer in 2011.
A loss of engine power due to the fatigue failure of the crankshaft counterweight retaining ring and the No. 6 connecting rod.
Source: NTSB Aviation Accident Database
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