What was found
2 NUTS FITTED TO MAIN ROTOR BLADE PITCH CHANGE HORNS ON ACFT R227/09 FOUND CRACKED IN SERVICE. FURTHER ENQUIRIES FOUND OTHER NUTS FROM SAME LOT NR 16838 SUPPLIED 7/09 FITTED TO H369 M/R DRAG DAMPER 7 OUT OF 12 NUTS ALSO CRACKED. INVESTIGATION LABS DISCOVERED HYDROGEN EMBRITTLEMENT OF NUTS. SUPPLIER TRACED MFG . MOST OF APPROX 400 NUTS SUPPLIED FROM THIS LOT NR 16838 TRACED AND AIRWORTHINESS ACTION PENDING. REMAINING 600 NUTS QUARANTINED. THIS IS A SIGNIFICANT ISSUE AS THESE STANDARD PARTS ARE FITTED TO NUMEROUS ACFT COMPONENTS.