ATL89FA078

According to the surviving passenger, a partial loss of pwr occurred drg flt & the plt tried to land in a field, but thefield was too short & the acft hit trees & crashed. Drg an exam of the eng, a metal fragment was fnd in the #3 cylinder. Evidence of foreign object dmg (peening) was fnd in the #2 & #3 combustion chambers & on their respective piston faces. The respective spark plugs were dmgd to the point that their ground electrodes had become displaced & shorted to the center electrodes. A metallurgical exam of the fragment revealed it was fm a broken exhaust valve; however, except for peening, the valves were intact. Further investigation revealed the eng had an exhaust valve failure in 1980 & had FLOWN98 hrs since then. Pieces of that valve were not fnd & were assumed to have been 'spit out' thru the exhaust sys. Drg anannual inspn on 1/12/89, an exhaust valve fragment was fnd in the eng muffler. The owner was notified; the exhaust pipeswere removed & inspected; no other fragments were fnd. The acft was not equipped with shoulder harnesses.