mlski

I appreciate you guys response. I went back and did a third engine run, but the problem did not duplicate... However, with the utility and booster rudder boost gauges, have you ever seen the needle in the gauge flux, meaning bounce up and down 3 to 4 times? Is this normal and is there an allowable flux as long as the flux returns to normal system pressure? I have never seen a hydrualic gauge flux. Usually, you will always get the initial drop once you have a demand on the system, but I have never seen needle bounce up and down and then stablize. What cause this flux with the rudder boost gauges? thanks

With all 4 engines running(normal grd idle), the copilot did the normal cycling of the flight controls and notice a 300-400psi drop on the utility and booster rudder boost pressure gauges. The needle on both gauges dropped 300-400 psi, then both gauges needles started to flux up and down. It did this in high and low rudder boost. When he cycled the elevator and elevator only, the drop was the highest(300-400psi), but with cycling the aileron we only noticed a 100psi drop, but with the the needles still fluxing, but not nearly as much. Does anyone know of a limitation with a flux with those gauges? I have checked my books and maintenance and have come up with nothing. We have also ruled out the #2 step down transformer. Thought it might be an idication that a boost pack might be going bad. Has anyone had this problem or any ideas that might help? Thanks