Bolt jammed tether's reel.

Investigators have attacked the nuts and bolts of the problems encountered during deployment of the Tethered Satellite System (SN: 8/15/92, p. 101) and found a bolt at fault.

Last-minute modifications to the satellite's tether-reel assembly included the addition of a quarter-inchdiameter securing bolt, which apparently jammed the mechanism inflight, a board of international investigators reported last week.

The board's preliminary analysis indicates that this bolt prevented the free movement of a device called the level wind mechanism, which feeds out tether much as a fishing reel feeds out line. This is believed to have caused the tether to jam first at 179 meters and again at 256 meters.

Although shuttle astronauts managed to clear both snags, this problem would have prevented the full deployment of the satellite even without the other failures that occurred during the mission, the board said.

Investigators continue to examine all of the major problems encountered during the mission, including an initial failure to deploy the satellite and the final tether snag, which developed at the far end of the deployment boom.