What happened
The aircraft experienced a ground collision followed by a roll while the pilot was conducting a hover taxi maneuver on the downwind side of the runway. At the time of the incident, wind conditions were reported at 15 knots with gusts reaching as high as 45 knots.
The investigation
Following the event, an Enstrom chief engineer reviewed the operational parameters and mechanical factors involved. The analysis indicated that performing a downwind hover taxi can lead to a decay in main rotor revolutions per minute (RPM). This decay is typically caused by the excessive use of tail rotor pedals required to maintain directional control against crosswinds.
Findings
The investigation highlighted two critical contributing factors. First, the aircraft was operating near its maximum gross weight, which exacerbates handling difficulties in high wind conditions. Second, the combination of heavy weight and strong downwind gusts placed excessive demand on the tail rotor system to maintain heading, leading to the loss of main rotor RPM and subsequent control issues.
Safety message
Operators should be aware that hover taxiing downwind at or near maximum gross weight can significantly reduce main rotor RPM due to increased tail rotor pedal input. This condition reduces available power margin and control authority, increasing the risk of loss of control.