On May 27, 1988, an Enstrom F-28A (registration N9209) was involved in an aviation accident near Middletown, DE. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
Shortly after takeoff at about 400 ft, a helicopter experienced a loud bang and severe vibration. The CFI performed an autorotation; the helicopter struck tree branches and landed hard. Post-accident inspection revealed a fatigue failure of the #3 cylinder connecting rod cap.
Incident Overview
Shortly after takeoff, while the helicopter was at an altitude of approximately 400 feet, a loud bang was heard. The helicopter subsequently developed moderate to severe vibration. The certified flight instructor (CFI) took control of the helicopter and initiated an autorotation.
Landing and Post-Accident Findings
During the autorotation, the helicopter contacted small tree branches and then landed hard in a field. A post-accident inspection revealed that the #3 cylinder connecting rod cap had separated from the connecting rod. The separation was due to a fatigue failure that initiated at the bolt hole in the yoke section of the rod. Additionally, severe galling was visible on the failed connecting rod cap and yoke.