On November 15, 1983, an Enstrom F28F (registration N8622U) was involved in an aviation accident near Hillsboro, OR. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An aircraft experienced a hard landing during autorotation after the engine ran rough and quit at 250 feet AGL during takeoff. The pilot had leaned the mixture prior to takeoff and was uncertain if he returned it to full rich when the engine misfired.
Accident Sequence
The aircraft was performing a takeoff when the engine began to run rough and subsequently quit at approximately 250 feet above ground level. The pilot initiated an autorotation, maintaining 50 miles per hour with minimal flare for landing. The landing was hard.
Investigation
Following the accident, the engine was examined and operated normally. The mixture control was slowly turned to simulate the conditions under which the engine had run rough. It was found that the engine ran rough when the mixture was approximately 3 inches from the full rich position. The pilot reported that he had leaned the mixture prior to takeoff and was not sure if he had pushed the mixture control to full rich when the engine started to miss and run rough.