CHI95LA139

Shortly after takeoff, as the airplane reached its assigned cruise altitude, the airplane's engine lost total power. The pilot made a forced landing in a field and during the rollout collided with a tree and ditch. Postaccident examination of the engine revealed that five of six hydraulic tappet body heads were separated from the tappet body. The tappet heads were found throughout the engine case. The reason for the tappet body head failures was not determined.

On April 30, 1995, at 1355 central daylight time, a Mooney M20J, N4145H, operated as a flying club airplane, experienced a total loss of engine power shortly after departure from Kirksville Regional Airport in Kirksville, Missouri. The airplane sustained substantial damage during the resultant forced landing. The certificated flight instructor and private pilot received minor injuries. The two passengers were not injured. Visual meteorological conditions prevailed for the flight, which operated on an IFR flight plan. The flight operated under 14 CFR Part 91, and originated from Kirksville, Missouri, approximately 1328.

According to the instructor and private pilot, the private pilot was seated in the front, left seat and conducted the flying duties throughout the flight. The private pilot reported, "Normal pre-flight run-up, take-off, and climb to assigned altitude. Just reached assigned altitude - 6,000 feet - loud bang, terrible engine vibration." The pilot stated that he declared an emergency and made a 180 degree turn to try to land at the departed airport. The pilot stated that the instructor pilot accomplished the emergency checklist but the engine did not restart. Due to oil on the windshield, the instructor pilot's view was totally obscured. The private pilot had some visibility and continued to fly the airplane.

The private pilot stated that he made an emergency landing in a field. During the rollout the airplane's left wing collided with a tree and separated from the fuselage. The pilot stated that railroad tracks were "...fast approaching. Did a 180 [degree] turn to right and slid across a drainage ditch backwards, stopping against the train track embankment...."

Postaccident examination of the internal engine case revealed metal contaminates (later identified as hydraulic tappet heads). The engine's rods, pistons, and cylinders were damaged. Five of the six hydraulic tappet body heads were entirely, or partially, separated from their respective tappet.

A metallurgical examination of the tappet bodies and heads were accomplished at the Safety Board's Materials Laboratory. The Metallurgist's Factual report denoted, "The head portion of tappet 1 appeared relatively intact. However, examination with the aid of a bench binocular microscope revealed regularly spaced slant indentations on the cam follower face...Visual examination reveled that the periphery of the head portions of tappets 2 and 3 were broken off. All fractures had a large-scale faceted appearance, as if sections of the tappet heads had broken off in segments. The cam follower faces [that] remained on the tappet bodies exhibited evidence of extensive wear. The fracture faces on tappets 2 and 3, and on all submitted separated pieces of tappets had a brittle appearance and their fracture features were typical of overstress separations...The head portions of tappets 4,5, and 6 were broken off and subsequently worn down to the cylinder portion. The wear between the contact surfaces of tappet 6 and the corresponding cam lobe developed a through-the- wall hole extending into an oil supply chamber."

A hardness test was accomplished on tappet 1. Hardness values obtained were above the minimum hardness specified by the manufacturer.

According to the airplane's engine log books, the engine was overhauled on March 17, 1994, about 190 hours prior to the accident. On June 27, 1994, about 138 hours prior to the accident, the engine received a "propeller strike inspection" and a 100 hour inspection.