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Description of Driving Event:

On April 4, 1990, at approximately 9:05 a.m. EDT, one of the three fuel cells (#3) installed in the Orbiter Atlantis, OV-104, was damaged while an attempt was being made to vent the fuel cell prior to its removal and replacement. Atlantis returned to the Kennedy Space Center (KSC) on March 3, 1990, after successfully completing the STS-36 mission. The vehicle was undergoing processing in the Orbiter Processing Facility (OPF) in preparation for the STS-38 mission in July of this year. Testing and processing was being accomplished by the Shuttle Processing Contractor (SPC) at KSC. The Fuel Cell Single Cell Voltage Test was accomplished on March 30 and 31, and the analysis of the test results indicated there were two degraded internal cells. A decision to remove and replace the fuel cell was subsequently made on April 2 by the Orbiter Project Manager.

The accident occurred while attempting to vent the fuel cell with the Orbiter hydrogen (H 2) purge vent port capped. This allowed the H2 pressure to exceed the oxygen (02) pressure in the fuel cell, 2 side of the fuel cell. The Potassium Hydroxide (KOH) was found at the 02 purge port of the fuel cell indicating the ninety-six internal cells, the regulator, and the accumulator would have to be replaced due to the corrosive qualities of KOH. No one was injured and damage was limited to fuel cell #3.