Incident Overview
On March 3, 2018, a helicopter EC 135 P2+ was involved in an incident at EPBC. The duty crew of the Warsaw unit had received clearance for a rescue flight. The pilot initiated the starting procedure using a ground power source. The left engine started without any anomalies.
Right Engine Start Issue
During the start of the right engine, the pilot observed a lack of rotation of the engine shaft. Additionally, a rise in gas temperature and an abnormal noise from the starter generator were noted. The pilot aborted the start sequence, shut down the left engine, and contacted the Technical Coordination Center (CKT).
Troubleshooting and Maintenance
The helicopter was grounded. During troubleshooting, the drive shaft of the right engine's starter generator was found to be sheared. A mechanic from the Warsaw-Babice maintenance station (SOT) replaced the damaged starter generator (serial number P2501) with a serviceable unit (serial number P1366), following the Aircraft Maintenance Manual (AMM 24-30-00, 4-2). After a test run, the starter generator operated without issues.
Return to Service
Following the repair, the helicopter was returned to service.
Probable Cause
The probable cause of the shearing of the starter generator drive shaft was its operational wear.
Preventive Actions
The event was discussed with all operational personnel of the LPR (Polish Medical Air Rescue service). No safety recommendations were formulated by the State Commission on Aircraft Accident Investigation (PKBWL).