On May 26, 2018, an EUROCOPTER, EC-135 (registration SP-HXG) was involved in an aviation accident near Zielona Góra Przylep (EPZP), PL. Investigators recorded the probable cause as: Operational wear of the bearings of the long drive shaft from the main gearbox to the fenestron. This summary draws on records from the Polish State Commission on Aircraft Accidents Investigation (PKBWL).
Aircraft registered SP-HXG. Photo: MaciekSnk / Public domain, via Wikimedia Commons
On 26 May 2018, a helicopter crew heard abnormal noises from the fenestron. Inspection revealed excessive heating of bearings in the long drive shaft. Bearings were replaced, and the aircraft returned to service.
Incident Details
On 26 May 2018, the duty crew from the Zielona Góra branch performed a flight to Nowa Sól for a medical emergency. The mission was completed and the helicopter landed at the base without any consequences. During a pre-flight inspection of the main rotor, while rotating it, the crew commander heard unnatural noises (crackling) coming from the fenestron area. The pilot informed the Technical Coordination Center (CKT) duty officer. The CKT decided to perform a cold start of the engines to confirm the unnatural sounds. After the test, an audio file was sent to the CKT.
Findings
The Technical Coordination Center grounded the helicopter from further operation. A maintenance technician from the base's maintenance station in Szczecin diagnosed the fault and determined that the cause was excessive heating of the bearings of the long shaft that transmits power from the main gearbox to the fenestron. Based on order no. 086/021/HXG/3/1, the technician replaced five bearings in the drive shaft supports with new ones.
Outcome
A ground run of the helicopter was performed with a positive result. The helicopter was returned to service. The incident was discussed with all operational personnel of the Polish Medical Air Rescue (LPR). The State Commission on Aircraft Accident Investigation did not issue any safety recommendations.
Probable cause
Operational wear of the bearings of the long drive shaft from the main gearbox to the fenestron.
