Presenter Date Page 1 October 30, 2006 Pre-decisional. Internal Use Only Design Overview Ground Side Flight Side Interface Seal GH 2 Vent Disconnect

Presenter Date Page 2 October 30, 2006 Pre-decisional. Internal Use Only STS-116 GUCA Performance Body Seals Pre STS-116 and STS-122 and subs STS-116

Presenter Date Page 3 October 30, 2006 Pre-decisional. Internal Use Only Background – Design / Leakage History (Pre-STS-116) STS-116 / ET-123 was first use of new ground umbilical disconnect flight seal design –One-piece seal replaced with flexible two-piece seal to accommodate misalignment during installation History of leakage with previous disconnect ground side / flight seal design STS-27 through STS-105 (>120 loadings) STS-108 through STS-115 (19 loadings) and STS-122 and subs STS-116/ET-123 (2 loadings) Design History Ground Side Bellows Probe Material: CRES 321 Spring Force: 165 lbs min. Material: Inconel 718 Spring Force: 225 lbs min. Material: Inconel 718 Spring Force: 225 lbs min. Flight Seal Design One-piece rigid seal Two-piece flexible seal Leakage History (11) occurrences of leakage. Contingency procedures required on (4) occurrences to reduce / control leakage No leakage observed(2) occurrences of leakage. Contingency procedures not required

Presenter Date Page 4 October 30, 2006 Pre-decisional. Internal Use Only Historical Changes Seal Graphic: Flight-Side Seal Configuration (Pre-STS-108 and Post STS-120) STS-116 Flight-Side Seal Redesign

Presenter Date Page 5 October 30, 2006 Pre-decisional. Internal Use Only IFA STS-116-T-001, Unexpected GH2 Leakage Critical Environments For Excessive Leakage Not Present During Majority Of Loading Operations Fast Fill Tank volume partially filled with LH 2 Ullage gas consists of mixture of GHe / GH2 – GH2 concentration increases as tank is filled Vent valve opening / closing Tank pressure: 32.9 – 43.2 psia Transition to Topping (leakage detected on STS-116) Valve opens and vents high concentration of GH 2 and some LH 2 into the vent line Vent line/umbilical interface exposed to rapid cryo cool-down/press. pulse Background – Loading Phases GH2 unavailable GH 2 vent valve open LH 2 GH 2 GH e GH 2 press. line Ground/ET Interface GH 2 vent valve GH 2 diffuser GH 2 vent line GH 2 vent valve closed LH 2 Terminal Count Vent valve closed – GH2 unavailable Replenish Steady-state thermal conditions present No delta pressure at umbilical / tank interface Less volume / lower concentration of GH2 than during topping phase LH 2 GH 2 vent valve remains open in Replenish