Incident Overview
On 18 September 2017, during a scheduled hangar maintenance check at the Warsaw-Babice maintenance station, a defect was identified on the main rotor blade of an EC135 P2+ helicopter. The inspection was conducted in accordance with Aircraft Maintenance Manual (AMM) 62-11-00, 6-1.
Defect Description
The defect, described as an irregular crack in the composite structure, was located at the edge of the mounting hole for the blade attachment bolt. Measured dimensions were approximately 4 mm in the horizontal plane along the hole edge and about 5 mm vertically along the hole. The affected blade was marked with red color.
Disposition
Per AMM 62-11-00, 6-1 E.26.b(2), the damage was classified as unacceptable. The maintenance organization queried the manufacturer (inquiry number TE-2017-EC 135-02221) regarding further action. Following consultation, the blade was shipped to the manufacturer for verification. The helicopter remained in scheduled maintenance as of the report date.
Probable Cause
The probable cause of the incident was a defect in the composite structure, detected after 2,492 flight hours during a scheduled maintenance check.
Follow-Up Actions
The incident was discussed with all operational personnel of the user organization (Polish Medical Air Rescue – LPR). No safety recommendations were issued by the Polish State Commission on Aircraft Accident Investigation (PKBWL).