After a blade failure and major overhaul, a Frame 5 turbine experienced severe oscillations in fuel flow and megawatt output during liquid fuel operation, leading to repeated trips and an unplanned outage. The Rx3i control system lacked the high-speed data needed for diagnostics. SISO deployed proprietary software to capture detailed running data, analyzed the entire fuel flow control loop, and identified a mis-tuned speed regulator gain. Through a multi-load tuning process, stability was restored across the operating range, returning the unit to service and ending the outage.