OXFORD, NC, USA
N9385C
Piper PA-32RT-300
During cruise flight, the pilot felt a vibration, which continued. Subsequently, oil began covering the windshield, and the engine lost power. The flight was vectored toward a nearby airport, but the pilot did not communicate his intentions of a forced landing over the correct UNICOM frequency. Due to an airplane ahead, he landed hard on the displaced portion of the runway. Several holes were noted in the crankcase near the Nos. 1 and 4 cylinders. Examination of the engine revealed that the connecting rods for the Nos. 1 and 4 cylinders had failed. Metallurgical examination of the failed components revealed high stress low cycle fatigue on the No. 4 rod. Also, galling was noted in critical areas on the Nos. 1, 2, and 4 connecting rods and/or caps. A service bulletin indicated that galling in critical areas could cause failure of connecting rods, and galling could occur as a result of high loading such as during engine overspeed or operation with excessive manifold pressure. The engine had been overhauled by the manufacturer and had accumulated about 1,252 hours.
On September 13, 1997, about 1215 eastern daylight time, a Piper PA-32RT-300, N9385C, co-registered to private individuals, landed hard during a forced landing at the Henderson-Oxford Airport, Oxford, North Carolina. Visual meteorological conditions prevailed at the time and an IFR flight plan was filed for the 14 CFR Part 91 personal flight. The airplane was substantially damaged and the commercial-rated pilot and 1 passenger were not injured. The flight originated about 1155 from the Raleigh-Durham International Airport, Raleigh, North Carolina. The pilot stated that before departure he added 1 quart of oil to the oil sump, which brought the oil quantity to about 10 quarts; the engine oil capacity is 12 quarts. He completed the remainder of the preflight, started the engine and performed an engine run-up before departure, with no discrepancies noted. The flight departed and while flying in VFR conditions at 5,000 feet mean sea level, at 22 inches manifold pressure and 2,400 rpm, he first felt a sudden vibration. He reduced power, increased the propeller blade angle, and turned on the boost pump which did not reduce the vibration. He advised the controller of the emergency and asked the location of the closest airport which the controller advised the pilot of. The pilot then advised the controller that the airport was in sight and he flew toward that location. He then secured the engine with the mixture control and simultaneously oil began covering the windshield. He was advised by the controller of the field elevation and runway length, but the controller did not provide him with the UNICOM frequency. He advised the controller that oil was covering the windshield and while descending, he asked his son, who is not a pilot, in part for the UNICOM frequency. His son did not know what he was asking for but he did select 122.7; the UNICOM frequency is 122.8. The flight continued toward the airport and while on a 1/8 to 1/4 mile final with the landing gear extended, he observed another airplane ahead on short final. He maneuvered the airplane to the right and the airplane touched down hard on the displaced threshold then bounced twice. The left main landing gear then collapsed and the airplane traveled off the left side of the runway coming to rest upright on grass. Examination of the engine by FAA airworthiness inspectors revealed a hole in the crankcase above the No. 4 cylinder, and the cylinder base nut for the upper aft, 3/8 inch diameter stud at that cylinder was not in place. Also, the upper forward 3/8 inch diameter stud for that same cylinder was extended from the crankcase but the nut was installed. A hole was also located above the No.1 cylinder, and a section of the crankcase beneath the No. 1 cylinder was missing. Disassembly of the engine revealed that the Nos. 1 and 4 cylinders connecting rods were failed. The failed components and associated hardware were sent to the NTSB materials laboratory for examination. Metallurgical examination of the failed connecting rod from the No.4 cylinder revealed high stress, low cycle fatigue. Most fractures had been severely damaged by post mechanical impacts. All undamaged fracture areas except the fatigue noted, exhibited evidence of overstress separation. Visual examination of the cylinder Nos. 1, 2, and 4 connecting rods and/or caps was accomplished. Ten separate areas of galling were noted on the No. 2 cylinder connecting rod and rod cap. All the areas were noted to be in critical areas, as described in Lycoming Service Bulletin No. 439A. With respect to the No. 4 cylinder failed connecting rod, galling was noted in the yoke area opposite the failed area. That area was also in a critical area. Examination of the No. 1 cylinder failed connecting rod revealed evidence of galling in one area. Review of the Service Bulletin revealed that the location of the galling determines if the rod is or is not likely to fail. The non-critical areas on the bearing bore of the connecting rod are directly under the I-beam of the rod. All other areas along the bearing bore are considered critical. The Service Bulletin also states that galling is caused by a movement between the surfaces of the bearing insert and the connecting rod during periods of high loading, such as produced during overspeed or excessive manifold pressure operation. Review of the maintenance records revealed that the engine was recorded as being overhauled/rebuilt by the manufacture on May 18, 1990. The engine was recorded as being installed in the accident airplane on August 2, 1990, at a tachometer time of 4,438 hours. The tachometer time at the time of the accident was 5,690.06 hours. According to overhaul records provided by the engine manufacturer, the connecting rods were reworked and during that process, an examination in part for fretting and galling was accomplished to the connecting rods and rod caps. The airplane, minus the retained engine components, was released to Mr. Mark Thompson of USAIG on November 24, 1997. The retained engine components were released to Mr. Mark Ash, the former co-owner, on June 19, 1998.
fatigue failure of the No.4 connecting rod in an area where galling had occurred, which resulted in loss of engine power and a forced landing. Related factors were: the pilot's lack of communication by failing to select the proper UNICOM frequency; and his failure or inability to flare the airplane during the forced landing, while avoiding another airplane that was landing on the same runway.
Source: NTSB Aviation Accident Database
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