On June 1, 1988, a Hiller UH-12E (registration N4029R) was involved in an aviation accident near Gretna, FL. Investigators recorded the probable cause as: The No. 3 cylinder connecting rod failed at the shoulder near the crankshaft journal due to fatigue. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During an aerial application flight, the pilot reported a screeching noise followed by engine failure. The helicopter landed hard, breaking its skids, and came to rest on its right side. Post-crash inspection revealed a connecting rod failed due to fatigue.
Accident Narrative
While conducting an aerial application flight, the pilot reported maneuvering the helicopter to release the remaining chemical. Shortly thereafter, he heard a loud 'screeching' noise, which was followed by silence as the engine quit. The helicopter subsequently landed hard, breaking its skids. The aircraft came to rest on its right side.
Post-Crash Inspection
A post-crash inspection of the engine revealed that the No. 2 cylinder was partially separated. Additionally, the No. 3 cylinder connecting rod had failed at the shoulder near the crankshaft journal. The failure was attributed to fatigue.
Probable cause
The No. 3 cylinder connecting rod failed at the shoulder near the crankshaft journal due to fatigue.