scope:

Description of Driving Event:

Several items of EVA hardware were lost during the EVAs on STS-88. Impact to immediate mission is loss of availability of needed tools. Lost tooling, when unretrieved, also adds to on orbit debris.

• The flight support equipment (FSE) for the EVA installable slidewire and an on-orbit installed worksite interface (OIWIF) with an attached retractable tether were lost on EVA1.

• One of the trunnion pin covers was lost on EVA2.

• Two of the safety tether hook guards were also lost during the EVAs.

There is no identified common hardware cause for the lost hardware. The EVA Project Office chartered a team to investigate the issue and make recommendations for corrective action.

Root cause:

• Slidewire Carrier - inconclusive, most probable cause is inadvertent opening of Tool Stanchion bayonet.

• On orbit installed WIF/retractable tether - inconclusive, most probable cause was the hardware was tethered to another end item and was released when that end item was removed from the mini workstation.

• Trunnion pin cover - was not properly tethered due to a lack of a tether loop on the mockup/ trainer.

• Tether hook clips - inadequate restraint in design.