External Thermal Control System (ETCS) Loop A Status: ETCS Loop A is still operating without full temperature control. The Loop A Interface Heat Exchangers (IFHX) are still bypassed and isolated, preventing internal heat rejection on loop A. ETCS Loop B continues to operate nominally. Due to the loss of heat rejection for the N2 Moderate Temperature Loop (MTL), half of the power loads in the N2, JEM and Columbus modules have been powered down. Overnight, the suspect Flow Control Valve (FCV) was successfully commanded through its entire range. The process commanded the FCV in 5 degree increments from the full radiator bypass position to the full radiator flow position and then returned it back to the full bypass position. Flow rates were measured to be less than expected.
At 3:50pm CST today the Flight Control Team removed power from ETCS Loop A Pump Control Valve Package (PCVP) and will leave it off for approximately 2 hours in an effort to regain FCV functionality. Engineering teams will continue to assess fault tree and impacts to the current on-board configuration.