AKRON, CO, USA
N51CC
PIPER PA-46-350P
DURING A CROSS COUNTRY FLIGHT ON AN IFR FLIGHT PLAN IN VFR CONDITIONS, ENGINE OIL PRESSURE DECREASED AND THE PROP WENT INTO OVERSPEED. THE PILOT SECURED THE ENGINE AND CONDUCTED A FORCED LANDING. HE ATTEMPTED TO GLIDE TO THE NEAREST AIRPORT BUT LANDED IN A WHEAT FIELD APPROXIMATELY 1,320 FEET SHORT OF THE RUNWAY. THE LANDING GEAR COLLAPSED AND THE WINGS AND FUSELAGE WERE DAMAGED. INVESTIGATION PROVIDED EVIDENCE OF OIL SCRAPER RING FAILURE WHICH RESULTED IN OIL EXHAUSTION. EVIDENCE OF OIL VENTING INTO THE EXHAUST WAS PRESENT.
HISTORY OF FLIGHT (Note: All time are depicted in mountain daylight time unless otherwise noted.) On June 25, 1994, at 1300, a Piper PA-46-350P, N51CC, sustained substantial damage during a forced landing in a field approximately one quarter mile short of runway 29 at Akron, Colorado. The pilot and one passenger received serious injuries, and the other passenger received minor injuries. Visual meteorological conditions prevailed for this personal flight and an IFR flight plan was filed. The trip originated from Kenosha, Wisconsin, at 0800 the day of the accident. A servicing stop was conducted at Grand Island, Nebraska, with the flight departing that facility at 1116. During that stop, the aircraft was serviced with 67.8 gallons of 100 LL aviation fuel and 2 quarts of engine oil. The oil level after servicing is unknown, and according to the owner, the fuel on board at the time of departure was 120 gallons. An IFR flight plan was filed and the route of flight was direct to Aspen, Colorado, with an assigned cruise altitude of flight level 200. At 1202, the pilot of N51CC contacted Denver Center and advised he was having "turbo" problems and requested a descent to 17,000 feet above mean sea level (msl). He was cleared to 17,000 feet and at 1216, the pilot requested and was granted a descent to 12,000 feet msl. At 1245, the flight advised center of oil pressure problems and requested vectors to the nearest airport. The controller advised that Akron was 300 degrees at 20 miles. At 1249, the pilot stated that he had lost the engine. At this time, the flight was 14 miles from Akron at 9,000 feet msl. At 1251 Denver Center lost radar and radio contact with N51CC and at 1257 another aircraft in the area reported an emergency locator transmitter (ELT) signal. The aircraft landed approximately 450 feet short of runway 29 at Akron in a wheat field. Following touch down on a heading of 290 degrees, the aircraft rotated to the left around the vertical axis, and came to rest on a heading of 210 degrees after sliding for 440 feet on a track of 290 degrees. (See attached diagram.) According to the pilot, when he began losing oil pressure, the propeller went into overspeed and he secured the engine. WRECKAGE AND IMPACT INFORMATION At the time of the landing in a wheat field, the landing gear was down and the flaps were up. The field consisted of loose sandy soil and unharvested wheat. Following touch down, all three landing gear failed upward and the engine broke loose from the upper mounts at the firewall. No oil was present on the dip stick and approximately 2 quarts of oil was recovered from the engine. Both wings were wrinkled on the upper and lower surfaces and the left aileron detached at the outer hinge. Integrity of the left wing fuel tank was lost. Fuel on board at the time of the accident is estimated to be between 80 and 100 gallons. The underside of the aircraft sustained damage at the antenna mounts with upward deformation of the structure. It was noted that the left side of the belly was coated with oil residue. The cockpit and cabin areas were undamaged with no exhibited deformation. All restraint devices were in place, undamaged and functional. TESTS AND RESEARCH The aircraft was recovered by Beegles Aircraft Services, Greeley, Colorado, and taken to their facilities. A representative of the engine manufacturer was present for an examination of the engine. Their report is an enclosure. Pictures submitted with that report have been removed and are the property of the manufacturer. Findings of that examination follow: Magnetos - The magnetos were removed from the engine and were not tested. Neither magneto was equipped with an impulse coupler. Spark plugs - Removal and examination revealed that all spark plug electrodes appeared normal. The plugs were dry except for number 6 which was oil fouled. Engine fuel system - The fuel servo was not disassembled or examined. Fuel was observed dripping from the inlet fitting when the unit was removed from the engine. Lubrication system - Oil residue from the oil lines, waste gate, turbochargers and oil cooler did not exhibit evidence of metal contamination. Both the oil filter and suction screen were contaminated with ferrous and nonferrous metal. In addition, metal was present in the oil sump assembly. The oil pump was removed and visually examined. The drive shaft could not be rotated by hand. Distress and metal contamination were present in the area around the drive shaft and housing bore. Scoring on the housing wall and pits in the oil pump gears were present. Valve and gear train - Continuity was visually checked during the course of the engine examination with no discrepancies noted. Crankcase - The crankshaft was free to rotate. All connecting rod bearings were distressed. The number 1 bearings still contained babbitt material, while this material was missing from the other bearings. All rods remained attached to the crankshaft. Distress on the crankshaft journals was present. Several of the connecting rod bearing caps had strike marks present on the piston skirts. The main and front bearings exhibited slight smearing from metal contamination. The breather system was visually examined. Oil residue was present in the breather line and inside the exhaust tail pipe assembly around the breather nipple. The oil stain was moist and dark. Cylinders - On cylinder number 1 piston, the second compression ring was found stuck, and the oil control ring was partially stuck. The top ring was free and rust was present on the cylinder wall. Cylinder number 2 piston rings were free and intact. Cylinders number 3 and 4 oil control rings were found stuck. Cylinder number 5 piston rings were free and intact. Cylinder number 6 cylinder wall exhibited some rust but no scoring was present and hone marks were present. The number 6 piston dome was saturated with oil residue. The oil control ring was broken in several places and was stuck in the ring land. Three of the four oil drain back holes were damaged and enlarged. The damage consisted of the holes being augured out. The compression rings were free and intact. Turbochargers - Teardown and examination of both turbochargers disclosed that both were capable of normal operation, and that the internal bearings and journals had not experienced unusual wear or damage. The wastegate was undamaged, and the internal parts of the wastegate actuator were normal. Oil residue was present in the overboard vent boss and on the outside of the piston below the seal assembly. The piston spring assembly had evidence of some oil residue, but no wet oil was observed in that area.
THE LOSS OF ENGINE POWER DUE TO OIL EXHAUSTION WHICH RESULTED FROM A FAILED OIL SCRAPER RING. A FACTOR WAS UNSUITABLE TERRAIN FOR A FORCED LANDING.
Source: NTSB Aviation Accident Database
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