Flight Crew Air Transport Pilot (ATP)
Human-Machine Interface
Aircraft Equipment Problem Less Severe
General Maintenance Action
Aircraft
We had initially requested the RNAV (GPS) Y RWY 05R to practice for proficiency. I thought it'd be a good idea in light of NOT a lot of KIND traffic. Upon a ATC radar vectored visual approach; backed up by a practice RNAV (GPS) RWY 05R approach; I had disengaged the autopilot at NO less than 500' AFE or nearing 1220' minimums or 5;000/1 for LNAV/VNAV. What happened next shortly after autopilot disconnecting was that the aircraft seemed to drift slightly to my right. The surface winds were about 050/6 (maybe from 040 - negligible). So; it appeared that there may have been 1 - 1 1/2 units of rudder trim already imputed. I trimmed towards neutral or 0 with the rudder trim control. The aircraft's bank angle was such that a slight or small right bank had developed (5-10 deg.?). Anyway; my goal at this point was to stop any drift towards the right of RWY centerline. So; applying left aileron control yoke pressure; it felt as if resistance was felt strongly enough to where the aircraft was now NOT responding to my inputs to correct and bank towards the left; slightly. My next measure was inputting some small incremental; left wing down aileron trim which definitely helped in my quest in that left small drift correction. Then did it seem as though the left aileron started responding. However; it still didn't seem quite as it should be. As if something was 'fighting' me on these inputs. The FO never had any hand on the control yoke as he had later stated when we had discussed it at the gate. I did write this condition up in the logbook. Furthermore; I had a lengthy conversation with two maintenance techs. I merely told them I had never experienced such a flight control sensation issue as this. I had given them as much information as I could assist them in troubleshooting this; as well as the pertinent details in the logbook write up. We did uneventfully touch down on or very close to the runway centerline. Nothing was ever said or communicated to Tower or Ground controllers about this issue. I was focused on flying the airplane safely and not wanting to induce any critical distractions this low to the ground. The FO and I debriefed this extensively while parked at the gate. I merely explained to him what I had experienced since he had very little feedback; other than what I had told him.
A B757 Captain; hand flying a practice RNAV (GPS) approach for proficiency development noted drift and bank conditions he attributed to an aileron or other roll control anomaly; advising roll control never felt 'quite as it should be.'