Departure and Initial Indications
The pilot departed Malcolm Mc Kinnon Airport (SSI) on an instrument cross-country flight to Peachtree DeKalb Airport. After leveling off at 6,000 feet, the engine analyzer No. 2 cylinder light began to flicker, followed shortly by the illumination of the low voltage light. The pilot contacted air traffic control (ATC) and requested to return to SSI.
Emergency and Diversion
After the request to return to SSI was made, the engine began to shake violently while making a loud "banging" noise, and the propeller stopped. The pilot informed ATC of the emergency and requested a diversion to the nearest airport. ATC diverted the pilot to Jesup-Wayne County Airport (JES). The pilot stated that he was unable to maintain altitude and subsequently crashed into a stand of trees approximately 2 miles southeast of JES.
Examination and Findings
The crankshaft was removed from the engine and sent to the National Transportation Safety Board's Office of Research and Engineering Materials Laboratory Division for further examination. The examination disclosed that the crankshaft was broken due to fatigue through the crank cheek between the No. 1 and No. 2 connecting rod journals.
History and Maintenance Records
Review of the airplane logbooks revealed that on November 20, 1989, a gear-up landing had occurred. Following that incident, the propeller was removed and the crankshaft was run-out, found to be 0.0006 inches out of round. According to Service Bulletin M84-16, which was in place at the time of the mishap, if any damage greater than "minor dressing of the propeller tips to correct the problem" occurs, a complete teardown must be performed. A teardown was not performed; instead, a serviceable propeller was reinstalled and the airplane was returned to service. The logbooks indicated that approximately 750 flight hours had accumulated on the crankshaft before it failed.