NTSB Factual Report

On January 17, 2005, at 1605 eastern standard time, a Beech C-23, N9JY, registered to and operated by a private individual, collided with trees following a loss of engine power after takeoff from a private turf airstrip in Roseboro, North Carolina. The personal flight was conducted under the provisions of Title 14 CFR Part 91 and visual flight rules. Visual meteorological conditions prevailed at the time of the accident and no flight plan was filed. The private pilot was not injured and the airplane sustained substantial damage. The flight originated at a private turf airstrip in Roseboro, North Carolina, on January 17, 2005 at 1600.

According to the pilot, he made a preflight inspection and run-up of the airplane prior to takeoff. He stated that after takeoff, as he climbed through 1,000 feet, he heard a knocking sound coming from the engine and immediately observed low oil pressure on the oil pressure gauge in the cockpit. He stated that within 60 seconds, "the engine seized" and the airplane began to lose altitude. The pilot stated he immediately turned toward an open field, established an approach, but collided with trees 40 yards short of the field. The airplane came to rest in a wooded area in a nose low, right wing low attitude.

The post-accident examination of the airplane revealed the right wing was partially separated at the root and the left wing was displaced aft. The horizontal stabilizer was separated from the empennage assembly. There was oil residue on the external oil hoses, the starter, and underside of the fuselage. There was also oil observed at the airstrip apron where the preflight run-up was conducted.

During the examination of the engine assembly, a readily visible crack was located in the first segment of the engine oil cooler adjacent to the joint between the first and second segments and in line with one of the oil ports. Further examination at the NTSB Materials Laboratory disclosed that the crack appeared to completely penetrate the thickness of the cooler over a length of 0.29 inch, although visible deformation extended beyond this length. The crack was gaped open up to 0.020 inch. Detailed visual examination of the exterior surface of the oil cooler revealed the presence of a second, much smaller, crack on the side of the cooler opposite from the side containing the readily visible crack. The smaller crack was in nearly an identical location as the readily visible crack, in the first segment of the cooler adjacent to the joint between the first and second segments and in line with the other oil port. The joint between the two segments had a slight jog near the crack location. The crack measured 0.088 inch long and was gaped open very slightly, on the order of several thousandths of an inch. It was noted that oil would seep out of this crack when the cooler was held with the crack on the bottom, confirming that the crack completely penetrated the wall thickness of the cooler. One face of the readily visible crack was cut from the remainder of the cooler; the crack surface was then cleaned and examined with a scanning electron microscope. The scanning electron microscope examination showed that the exterior portion of the crack was damaged, apparently by contact with the mating face of the crack, and that fracture features on undamaged portions consisted of ductile dimples, indicative of overstress fracture. No evidence of fatigue cracking or other type of progressive cracking was noted during the scanning electron microscope examination.

According the engine maintenance logs, the engine oil cooler was overhauled 442 hours before the accident on June 19, 2000.

NTSB Probable Cause

The overload fracture of the engine oil cooler for undetermined reasons.