Space Shuttle Main Engine:

NASA Has Not Evaluated the Alternate Fuel Turbopump Costs and Benefits

NSIAD-94-54: Published: Oct 29, 1993. Publicly Released: Oct 29, 1993.

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Donna M. Heivilin
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GAO reviewed the National Aeronautics and Space Administration's (NASA) planned development of an alternate high pressure fuel turbopump for the Space Shuttle's main engines, focusing on whether NASA has adequately analyzed cost, performance, and expected program benefits in comparison to other alternatives before resuming its development of the alternate pump.

GAO found that: (1) the current engine pump is safe and reliable if existing safety controls are effectively implemented; (2) NASA supports continued development of the alternate pump because of safety concerns about some aspects of the current pump's design; (3) NASA has not analyzed the costs and benefits of modifying the existing fuel pump because a major upgrade will require an expensive full certification test; (4) NASA has not determined what contribution the alternative fuel pump will make to the Shuttle's reliability in conjunction with other engine safety improvements; (5) the alternate fuel pump will require extensive testing and possible redesign as problems occur; (6) NASA did not analyze the costs and benefits of modifying the existing fuel pump and other alternatives before resuming development of the alternate pump; and (7) NASA expects that the alternate pump will reduce operating costs by decreasing inspections and maintenance, but it has not estimated the expected savings.

Recommendation for Executive Action

  1. Status: Closed - Not Implemented

    Comments: NASA did not agree to comparatively assess the life-cycle costs of AFP and the existing pump before restarting the AFP development program. The NASA explanation is based on its belief in the overriding importance of the safety considerations of replacing the existing pump. AFP is intended to increase the safety margins of the space shuttle's main engines.

    Recommendation: The Administrator, NASA, should require agency officials to estimate the life-cycle costs and benefits for the alternate fuel pump program and compare those with the costs and benefits of further improvements to the existing pump before deciding whether to resume development of the alternate fuel pump.

    Agency Affected: National Aeronautics and Space Administration


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