NTSB Identification: CHI01LA152.
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Accident occurred Sunday, June 03, 2001 in Jerseyville, IL
Probable Cause Approval Date: 05/28/2002
Aircraft: Allen Rotorway 162F, registration: N242KA
Injuries: 1 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The experimental amateur-built helicopter impacted muddy terrain and rolled over when its skids became stuck in the mud during an emergency autorotation following a total loss of engine power. The pilot reported that after the number one electronic control unit (ECU) had failed followed by the number two ECU failing while returning to the departure point at an airspeed of 40 mph and at an altitude of 100 feet agl. An operation at 40 mph and at 100 feet agl was within the shaded region of the height velocity envelope for the helicopter. A postaccident engine run was performed while operating on the primary and secondary fully automated digital electronic control systems. Inspection of the number one electronic control unit revealed two resistors damaged within its circuit board. The number one ECU was found to be inoperative during testing and the number two ECU did not communicate with the number one ECU.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

the improper autorotation by the pilot. Contributing factors were the engine failure for undetermined reason(s) and the muddy terrain.

Full narrative available

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