ISLE OF WIGHT, VA, USA
N4595Z
Piper PA-22-108
The pilot stated that the airplane began to vibrate slightly while in cruise flight, and he decided to return to the airport. The engine then began to shake violently, and the pilot performed a forced landing. The airplane landed short, nosed over, and came to rest inverted. Examination of the wreckage revealed that the left rear cylinder on the engine had separated from it's mounting flange. The engine had accumulated about 13 hours since overhaul, when all four cylinders were replaced on the engine with chromed cylinders purchased from an outside source, then overhauled by the engine overhaul facility. During the metallurgical examination of the failed cylinder, a fatigue origin was found near the bottom of the fin radius, between the tenth and eleventh fins from the inboard end of the cylinder barrel. Severe corrosion attack was also observed on the fin immediately adjacent to the fatigue origin location. Corrosion damage was also noted in the radius, including a corrosion pit from which the crack arrest features appeared to emanate. The corrosion pit was filled with a non-conductive substance.
On July 11, 1999, about 1430 Eastern Daylight Time, a Piper PA-22-108, N4595Z, was substantially damaged during a forced landing near Isle of Wight, Virginia. The certificated private pilot was not injured. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight conducted under 14 CFR Part 91. The pilot stated that the airplane began to vibrate slightly while in cruise flight, at about 1,800 feet above the ground. The pilot also noticed a decrease of 100 rpm on the engine tachometer, and decided to return to the Hampton Roads Airport (PVG), Portsmouth, Virginia. As the airplane continued toward PVG, the engine began to shake violently, and the engine rpm decreased rapidly. The pilot selected a freshly cut peanut field, reduced engine power, and started a descent to a forced landing. After realizing the airplane would not make it to the selected field, the pilot attempted to add power, but the engine did not respond. The airplane then landed short, struck corn stalks, nosed over, and came to rest inverted. Examination of the wreckage by a Federal Aviation Administration Inspector revealed that the left rear cylinder on the engine had separated from it's mounting flange. Damage to the engine crankcase was local to the vicinity of the failed cylinder. The engine turned smoothly by hand, and the remaining three cylinders were not damaged. The Inspector further revealed that the engine had accumulated about 13 hours since it was overhauled during the month of January 1999, by the facility where the pilot worked. All four cylinders were replaced on the engine with chromed cylinders purchased from an outside source, then overhauled by the engine overhaul facility. The total time and cycles of the engine and cylinders, prior to the overhaul, could not be determined. The pilot additionally stated to the FAA Inspector that he had been trying to locate a mysterious oil leak on the side of the engine of the failed cylinder. The failed cylinder was forwarded to the NTSB Materials Lab in Washington, D.C. on August 4, 1999. According to the NTSB Materials Lab Factual Report, the cylinder was separated through the eight and eleventh fins outboard of the attachment flange, along a fracture plane that spiraled slightly around the cylinder. A fatigue origin was found approximately at the bottom of the radius between the tenth and eleventh fins, from the inboard end of the cylinder barrel. Severe corrosion attack was also observed on the fin immediately adjacent to the origin location. Corrosion damage was also noted in the radius, including a corrosion pit from which the crack arrest features appeared to emanate. The corrosion pit was filled with a non-conductive substance. Energy-dispersive spectroscopy of the material revealed large amounts of titanium, a common material in many paints. A large amount of oxide on the surface of the fracture, which resists cleansing, prohibited observation of fatigue striations on the surface.
The improper visual inspection of overhauled engine components by maintenance personnel.
Source: NTSB Aviation Accident Database
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