Narrative:

This jet required 5 units of left rudder trim in level flight. It also required multiple rudder trim adjustments on approach. We wrote this up; and the jet was taken out of service. It was out of service for about three days.turns out the rudder was out of rig; the rudder ratio changer had to be replaced; there was a damaged shear pin in the original rudder ratio changer; the rudder ratio changer input rod had a broken bearing; and the control rod for the upper rudder power control actuator had a broken nut plate and frozen bolt. At least I think that's what happened -- the maintenance history is a little hard to follow -- especially since we no longer have access to the [electronic] logbook!I don't know how long it had been flying around like this; but I wanted to give this some visibility via [safety report] because flight control system malfunctions are rare; at least in my experience. A malfunctioning rudder ratio changer; in the right failure mode; could potentially be catastrophic.

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Original NASA ASRS Text

Title: B757 Captain reported excessive rudder trim inputs were needed during flight.

Narrative: This jet required 5 units of left rudder trim in level flight. It also required multiple rudder trim adjustments on approach. We wrote this up; and the jet was taken out of service. It was out of service for about three days.Turns out the rudder was out of rig; the rudder ratio changer had to be replaced; there was a damaged shear pin in the original rudder ratio changer; the rudder ratio changer input rod had a broken bearing; and the control rod for the upper rudder power control actuator had a broken nut plate and frozen bolt. At least I think that's what happened -- the maintenance history is a little hard to follow -- especially since we no longer have access to the [electronic] logbook!I don't know how long it had been flying around like this; but I wanted to give this some visibility via [safety report] because flight control system malfunctions are rare; at least in my experience. A malfunctioning rudder ratio changer; in the right failure mode; could potentially be catastrophic.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.