scope:

Description of Driving Event:

After the STS-83 mission metallic particles were found in several locations of the SpaceLab module floor. This FOD was determined to be from the Express Rack Flight experiment, which included a Space Station International Standard Payload Rack. The source of the FOD was determined to be metal particles entrapped in inaccessible areas of the rack. All of the metal particles were trapped in the Spacelab module subfloor so there was no crew exposure to floating metal particles. The incident occurred after Boeing Huntsville had already taken steps to correct the processes that were generating the FOD so there was no impact on the factory operations. While actions to control the FOD in the assembled rack were taken prior to the flight, they were not 100% effective due to the restricted access to the rack interior once the flight experiment was assembled.

Based on this incident it is apparent that extraordinary efforts will be required to ensure and maintain the cleanliness of the ISS interior hardware. There are many inaccessible areas where an inspection to ensure "visibly clean" will require more than a simple visual inspection.