What happened
During a scheduled periodic inspection of an Airbus Helicopters/Eurocopter EC-135P2+ helicopter at the Heli Invest sp. z o.o. Services base (EPBC), maintenance personnel discovered a defect in the transmission system. The inspection revealed a broken spring pin (Part Number L651M1008217) located within the attachment of the long fenestron drive shaft end.
At the time the defect was identified, the aircraft had accumulated 356 flight hours since its last significant milestone. The incident was recorded as an occurrence involving the operator DIM SA.
The investigation
Following the discovery, the operator notified both the user and the Type Certificate holder to request technical consultation and assistance in determining the root cause of the failure. The investigation included a physical examination of the fractured component. Analysis of the fracture surfaces indicated that the break did not exhibit characteristics of material fatigue.
Findings
- A broken spring pin was found in the fenestron drive shaft assembly.
- The fracture surfaces showed no evidence of fatigue.
- The specific cause of the pin failure could not be determined.