Abstract—This research studies the performance characteristic, Static Transmission Error (STE), of a spur gear pair rotating under friction with and without damage in the form of a pit on gear teeth. Using a profilometer scan of a pit from an aerospace test gear, a damage shape in the form of parabolic profile pit is simulated on the surface of tooth of spur gear at seven different locations having three different sizes of the damage profile depth. Using the measured pit depth from profilometry, two additional pit depths were simulated by multiplying the initial profile depth by 5, and then by 10, for a total of three different profile depths having the same pit width. Similarly, six different coefficients of friction starting from zero to a maximum of 0.30 in the intervals of 0.06 were investigated. The combination of seven different locations of pits, six friction coefficients, and four pit depths resulted in a total of 168 unique combinations. Analyses were completed and multiple outputs responses including the STE were recorded, but only STE results are presented in this paper. Results show that STE variation increases with increase in friction coefficient and the size of damage.