Abstract
During a Shuttle flight in the early part of 1999, one of the crewmembers was unable to operate the backrest lever for the new lightweight seat in microgravity. It is essential that the crewmembers are able to adjust this backrest lever. Hence, an experiment was designed to investigate the amount of pull force exerted by subjects, wearing an unpressurized or pressurized crew launch/escape suit, when controls were placed in the front and back (on the right side) of the lightweight seat. The results from this study showed that subjects were able to pull on the lever at the back position with only about half the amount of force that they were able to exert on the lever at the front position. The results also showed that subjects wearing the pressurized suit were unable to reach the seat lever when it was located at the back. The pull forces on the front lever diminished about 50% when subjects wore pressurized suits. Based on these results from this study, it was recommended to NASA that the levers should not be located in the back position. Further investigation is needed to determine whether the levers at the front of the seat could be modified or adjusted to increase the leverage for crewmembers wearing pressurized launch/escape suits.
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