In Senegal, process-control systems are employed to enhance engineering quality control in manufacturing processes. A randomized field trial was conducted over six months with 150 participants. Participants were randomly assigned to either the treatment group (using process-control systems) or control group (no system). The proportion of defects in treated groups was found to be significantly lower than that in control groups (p < 0.05). The randomized field trial demonstrated significant reliability improvements with the use of process-control systems. Recommendation for implementation of process-control systems based on findings and to further enhance quality control measures. Process-Control Systems, Engineering Quality Control, Randomized Field Trial, Reliability The maintenance outcome was modelled as $Y_{it}=\beta_0+\beta_1X_{it}+u_i+\varepsilon_{it}$, with robustness checked using heteroskedasticity-consistent errors.