On July 9, 1998, a Hughes 369D (registration N5063G) was involved in an aviation accident near Raymond, WA. Investigators recorded the probable cause as: The splice at the opposing end of the polypropylene line was not in accordance with acceptable industry standards, leading to its failure and release of the load. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During a helicopter lift of cedar shake blocks, a polypropylene line with a defective splice released, causing the load to fall and fatally strike a ground crewman.
Incident Overview
Two ground crewmen were preparing cedar shake blocks for movement by a helicopter. They used a three-quarter-inch diameter yellow plastic line provided by the contractor. The line, made of polypropylene, had each end attached to itself via a woven splice to create a loop. The line was centered around the load, with one spliced loop end threaded through the opposing spliced loop. The free loop end was placed into the hook at the end of the helicopter's sling line.
During the helicopter's liftoff, the spliced end of the line at the helicopter's long-line hook released. This caused the cedar shake load to fall freely, striking and fatally injuring one of the ground crew personnel.
Examination Findings
Post-crash examination of the line revealed that one end of the line had unraveled. Additionally, the splice at the opposing end was not spliced in accordance with acceptable industry standards.
Probable cause
The splice at the opposing end of the polypropylene line was not in accordance with acceptable industry standards, leading to its failure and release of the load.