B757 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 171; Flight Crew Type 561
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Aircraft
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.
B757 Captain reported excessive rudder trim inputs were needed during flight.