scope:

Description of Driving Event:

The mishap occurred in the air drive section of a research wind tunnel. During an evening research run, a six foot stepladder was drawn into the wooden drive blades of the tunnel. The stepladder was destroyed and the wooden blades were damage.

The investigating committee determined that the principal cause of the mishap was the unsecured stepladder left in the tunnel by day shift personnel who used it for inspection purposes. Factors that contributed to the mishap were: the distraction of tunnel operator/mechanic by other duties, inadequate checklist elements that would require verification that the tunnel is clear for operation, and no requirement for a pre-run tunnel walk through just prior to a test run.