On June 17, 1986, a Hiller UH-12E (registration N172ET) was involved in an aviation accident near Delano, CA. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter rotor blade delaminated shortly after departing the operator's north base in Delano, California. Investigation revealed extensive voids along the bond line. The blade had been rejected by the manufacturer as unairworthy and purchased by the operator in as-is condition.
Incident Details
Shortly after departing the operator's north base in Delano, California, a helicopter rotor blade delaminated. The incident occurred during the initial phase of flight.
Investigation Findings
Post-incident examination determined that the blade contained extensive voids on the bond line. The investigation also revealed that the blade had been rejected by its manufacturer as unairworthy. The operator acquired the blade in an as-is condition and could not produce any yellow serviceable tags for the component. Investigators were unable to determine who had performed the last overhaul on the blades.
Maintenance History
The blade's provenance included a rejection from the manufacturer due to unairworthiness, yet it was purchased by the operator without documentation of serviceability. The lack of yellow serviceable tags and the inability to identify the overhaul facility further complicated the maintenance record.