Multi-user Droplet Combustion Apparatus (MDCA): Wilmore reviewed procedures and gathered hardware and tools for MDCA Hardware Replacement Part 1. Today’s activity had the crew configure the Fluid Combustion Facility (FCF) MDCA Chamber Insert Assembly (CIA) in support of the Flame Extinguishment Experiment-2 (FLEX-2) Binary-Droplet Array test points. Crew then removed the MDCA CIA from the CIR Combustion Chamber, restrained it to the Maintenance Work Area (MWA), removed the MDCA Fiber Arm, removed both MDCA Igniters, replaced the MDCA Color Camera, and re-installed the MDCA CIA in the Chamber. FLEX-2 uses small droplets of fuel to study the special burning characteristics of fire in space. The FLEX-2 experiment studies the rate and manner in which fuel is burned, the conditions that are necessary for soot to form, and the way in which a mixture of fuels evaporate before burning. The results from these experiments will give scientists a better understanding how fires behave in space and will provide important information that will be useful in increasing the fuel efficiency of engines using liquid fuels.