Incident Details
On 25 September 2017 at 13:23 local time, the crew of an EC 135 P2+ helicopter was conducting an Operational Proficiency Check (OPC) in accordance with the Operational Manual Part D. During a simulated engine failure before the takeoff decision point (TDP), the main rotor RPM dropped below 95%. This triggered an automatic deactivation of the training mode, resulting in a torque exceedance on both engines: left engine 87% and right engine 86% for 1.125 seconds.
After landing, the crew reported the occurrence to the Technical Coordination Center (CKT). By decision of the CKT, the helicopter was grounded.
Investigation and Findings
The CKT consulted with the Maintenance Station (SOT) in Szczecin. A mechanic performed an inspection of the helicopter in accordance with MSM 05-51-00, categories A through D. No abnormalities were found during the inspection, and the helicopter was returned to service.
The investigation was conducted by the State Commission on Aircraft Accident Investigation (PKBWL). No safety recommendations were issued.
Probable Cause
The probable cause of the incident was a reduction in the high vertical descent rate and an unexpected change in weather conditions, specifically wind direction and strength.
Actions Taken
The operator discussed the incident with all operational personnel. The helicopter was subsequently returned to normal operations after the inspection found no defects.