Incident Overview
An occurrence took place while a helicopter was in a hover to track and balance the rotor system. A main rotor blade and grip separated from the aircraft. The main rotor blade and grip were subsequently examined.
Examination Findings
Examination determined that the separation was due to fatigue cracking of 40 out of 49 main blade strap laminates. The blade that had been changed and did not separate was found to have 26 out of 49 main blade strap laminates separated due to fatigue. The fatigue initiated at the strap pin hole.
Maintenance History
The main blade straps have a life limit of 1,200 flight hours. Logbook records showed that the main blade straps were installed in the rotor hub assembly during an overhaul in Singapore, 640.4 flight hours before failure. The main rotor straps were reported to be new when installed.
Technical Details
The main rotor blade had been previously changed during troubleshooting of the main rotor system. The specific aircraft type, registration, operator, location, and other details are not provided in the source material.