AAIB investigation to Robinson R22 Beta, G-KKRN
Inadvertent engine shutdown leading to autorotation, near Wokingham, Berkshire, 3 February 2025
At approximately 800 ft agl while approaching White Waltham, the trainee pilot inadvertently moved the fuel mixture control to the lean position instead of selecting the carburettor heating (carb heat) on. The selection of lean caused the engine to stop. After immediately taking control, the instructor established the helicopter in autorotation but did not have sufficient time and height available to initiate an engine restart. While the helicopter experienced a partial rollover on landing, neither pilot was injured in the accident.
The risk of misidentification of the mixture control when selecting carburettor heating in the Robinson R22 Beta (R22) was first formally documented by the manufacturer in January 1981. The instructor was aware of the mis-selection risk and had briefed his student on the correct operation of the controls before the accident flight.
This accident is a reminder that, while risks can be identified and mitigated, the limitations of human performance mean lapses leading to risks maturing cannot be completely eradicated.
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