scope:

Description of Driving Event:

The supply system for the 750 psig GN2 is designed such that pressure may not be removed from flodyne valves for removal/replacement, a SCAPE operation, without removing pressure which actuates other relevant components. Inadequate isolation capability of actuation pressure could result in loss of valve control, allowing valve to open when it should be closed. This could allow trapped residuals in the cross country line to drain back to the storage area, possibly resulting in a hypergol spill or fire.