NASA-LLIS-0020

Abstract

<strong>Description of Driving Event:</strong> <br>A dual suit pressure controller failed to pressurize a crew coverall during manned suit testing and the shuttle flight STS-37 Terminal Countdown Demonstration Test (TCDT). The coverall is donned by an orbiter crew member during launch and entry. No previous failures of this type had occurred before. Upon disassembly of the suit, a small piece of fabric reinforced elastomer material (from a seal called a neck dam that separates the head and torso parts of the coverall) was found lodged inside the controller on the primary diaphragm assembly seat. Before the TCDT, a rapid replacement of the neck dam was performed. The usual, but undocumented, step in the replacement procedure that called for component removal before changing the neck dam did not occur. The piece of elastomer from the old neck dam remained in the suit as debris and migrated to the diaphragm during the pressure cycling. The corrective actions included: (1) documenting the procedural steps to require component removal, (2) protecting the component area from debris by adding plastic sheeting, and (3) vacuuming the inner volume of the coverall and inspecting it following all maintenance work. A failure of a coverall of this type during flight could result in the loss of the crew member if cabin pressurization failed.