What happened
During a cruise flight at 14,000 feet mean sea level, the aircraft engine experienced a failure. Air traffic control vectored the aircraft toward a nearby airport; however, the pilot flew toward a different airport, resulting in a crash in a residential area.
The investigation
Mechanical examination of the engine revealed that only 1.8 quarts of oil had been drained. Investigators found that three of the six connecting rods had failed due to a lack of lubrication. Further inspection showed detonation damage on the No. 6 cylinder piston and scoring on the piston sidewalls in five of the six cylinders. Additionally, heat discoloration was present on the connecting rod journals for three cylinders.
The aircraft's turbine inlet temperature (TIT) gauge was found to be inaccurate. The gauge had been miscalibrated by 30 to 40 degrees at the time of manufacture and was indicating 110 degrees Fahrenheit low when near the maximum continuous operating point of 1,750 degrees.
Investigators also discovered that the air/oil separator hose leading to the scavenge pump was blocked approximately 10 inches along its length by a substance with a high lead content. This blockage was linked to previous pilot reports of excessive oil consumption. Due to these consumption issues, four of the six cylinders had been replaced within the six months preceding the accident. Furthermore, one cylinder piston had been replaced approximately one month prior to the crash after being found to have sidewall damage consistent with detonation.