While liquid oxygen loading into the interim cryogenic propulsion stage continues and core stage tanks continue to be replenished with propellants, engineers are troubleshooting an issue conditioning one of the RS-25 engines (engine 3) on the bottom of the core stage. Launch controllers condition the engines by increasing pressure on the core stage tanks to bleed some of the cryogenic propellant to the engines to get them to the proper temperature range to start them. Engine 3 is not properly being conditioned through the bleed process, and engineers are troubleshooting.
Teams also are assessing what appears to be a crack in the thermal protection system material on one of the flanges on the core stage. The flanges are connection joints that function like a seam on a shirt, are affixed at the top and bottom of the intertank so the two tanks can be attached to it.