Significance of a Rotor Blade Failure for Fleet Operation, Inspection, Maintenance, Design and Certification

摘要

The catastrophic fracture of a rotor blade from a large helicopter was analyzed, with essentially immediate consequences for continued fleet operation, inspection and maintenance of the same type of rotor blade. Fractography indicated that the hollow blade spar had failed by fatigue originating from one or two corrosion pits under the spar/pocket joint. The service failure investigation was reviewed to serve as an essential illustration for subsequent discussion of remedial action for similar types of rotor blades, and design aspects, philosophy and procedure. This includes the adhesive bonding system, the pressurizing gas crack detection system, rotor blade working stresses, and estimation of fatigue initiative and crack growth lives.