sTEm–at-Work Puzzle #37: Machine System Performance

A Certified Process Technician, CPT, is reviewing the “Run Charts” for two machine systems, System #425 and System # 638, to assess their performance and determine if either, or both systems’ preventive maintenance schedules should be interrupted with an unscheduled maintenance check. Among other tasks, each system is milling shear pins to a specified radius for use in the propeller subsystems of a marine engine the company makes. To accomplish this system assessment task, the Tech routinely randomly selects pins to measure and record their radius. Because of the knowledge and skills expected of a CPT, the technician understands the implications presented in such Run Chart data.   

The plots below summarize system performance by presenting daily average radius measurements performed by the Tech. After studying this information the Tech has made a decision.   

1) The technician decided that both systems are operating as expected. Yes or NO. Submit your answers below the blog post, or on