In marine scope especially on ships, pneumatic control systems are applied in ramp door ships, navigation door, and also valve mechanism that used air flow as moveable fluid. A testing method for feedback instrument type PCM140 are using standard testing signal to analyze system response, there are step, ramp, and sinusoidal. While in caused of dashpot in second order system, the characteristic of second order system shows with damping ratio and overshoot. This research using an experimental method with experiment and analyze the data. As a result of analysis, obtained that time constant of the system 0.151 seconds (first order) and 0.359 seconds (second order), with a delay time 1.056 seconds (first order) and 0.013 seconds (second order). In the second order system has damping ratio 0,3 with the overshoot 0.37%. The sinusoidal frequency is 88.13 with the amplitude ratio 1.208 and phase lag is 85.71° for first order, and sinusoidal frequency is 0.762 with the amplitude ratio 1.66 and phase lag is 76.59° for second order. This results verified that, with the damping in the system, the system response become smooth (less vibration because of sine wave produced is interruptedly). With the results from analysis can be concluded that feedback instrument type PCM140 condition is still in good condition.