Overview
On October 10, 2017, at 10:35 LMT, a Guimbal Cabri G2 helicopter, operated by the AOSL WSOSP Dęblin, experienced an in-flight anomaly during the approach phase at EPDE Dęblin. The pilot, the sole occupant, was not injured. The incident involved intermittent warning indications on the power indicator (MIL) display, leading to a loss of power readings just before landing.
Incident Details
While completing a training task in a square pattern and approaching the entry gate, the pilot observed the MIL display change from white (normal operation) to yellow (caution). Subsequently, the display flickered between yellow and white at short intervals. Moments before touchdown, the indications disappeared entirely, then reappeared intermittently. After landing and engine shutdown, power indications fluctuated between 0% and 20%. When electrical power was reapplied, a "throttle fault" warning appeared.
Maintenance Findings
The helicopter was grounded following the incident. The maintenance organization determined that the erratic power indications were caused by a faulty throttle position sensor. In accordance with service bulletin SB14-031D, the sensor (part number HG70-2308, serial number 120025) was replaced along with the SB14-031 kit. Adjustment was performed per maintenance manual MM 72-A10. After the replacement, the throttle position measurement system functioned correctly, and the helicopter was returned to service.
Cause
The probable cause of the incorrect engine power indications was a faulty throttle position sensor.