scope:

Description of Driving Event:

"Hi-Lite" (similar to Hi-Lok) pin and collar fasteners are widely used on ISS Power Module structural assemblies. As part of an internal sharp-object-damage (SOD) identification and mitigation activity, it has been noted that small burrs are present on most installed collars. When accessible to an astronaut's EMU external surfaces, these burrs pose a sharp object hazard with risk of damage to the EMU outer fabric.

Root cause: As part of "Hi-Lite" fastener installation, a wrench is applied to a drive nut integral with the fastener collar. At a given torque, the drive nut shears from the collar body; the drive nut is then scrapped. This shearing action typically leaves burrs on the collar surface.