Narrative:

Event that is the subject of this report was first observed on ILS approach. Approaching the airport; we received radar vectors for the transition to the ILS approach from the approach controller. A prior event; (may or may not be related to this event); occurred about 30 minutes prior to TOD and was managed and documented with maintenance control. A CDU issue occurred as follows: selecting either navigation rad (navigation radio) on either CDU caused the respective FMC to 'timeout'. Followed by a loss of LNAV; VNAV; and autothrottles. VNAV speed and cruise data were also lost in the FMC. All autoflight functions were successfully restored; route was checked and verified; and the respective FMC returned to full function without navigation rad available. Autoflight; autothrottles; LNAV; VNAV; all restored. Maintenance control proposed a test: selecting both fmcs to source 'left' and retry navigation rad. Same results as above: 'timeout' on respective side FMC where navigation rad CDU key was selected; loss of LNAV; VNAV; autothrotte. Again; all these functions were manually reselected and restored. We were VMC at this point; prior to top of descent (TOD).next we tried both fmcs source both 'right'; same results as above. Maintenance control advised. (Dispatch advised he was monitoring our ACARS comm with maintenance control). Maintenance log entry made as per SOP. All functions; including all auto flight functions were operating from TOD through approach phase. Navigation rad was north/a on either CDU. What follows is the subject of this report. I don't know if the event below and the issue documented above are related.on approach; aircraft configuration was managed as per profile; SOP. Gear was selected prior to FAF. Flaps 20 at FAF. Inside FAF; PF observed unusual amount of control wheel displacement. Winds were relatively steady; little or no crosswind; mostly a direct headwind; reported at 10 knots. Fuel was balanced. Captured on localizer on GS; PF managing speed and flaps (flaps 30 planned; briefed) to target values. Landed flaps 30.inside FAF; PF and PNF both observed left control wheel displacement of about 3-4 degrees wing down. We were IMC transitioning to VMC below a variable layer at about 500-1000 ft. Visibility was good; reported at 10 NM. Captain directed and first officer confirmed; autopilot and autothrottles off for the balance of the approach. Autopilot and autothrottles were disconnected. At disconnect; PF observed and stated to the effect: 'the flight controls (in roll) were sloppy or lose' i.e.; flight controls did not feel typical for this phase/configuration. The aircraft was fully controllable. The yoke had more 'play' or 'slop' but was responsive; in all axis. The PF and pm both physically observed and verified the roll degradation from typically observed in this configuration at these speeds. We were not slow. Target was 135 KIAS. A normal approach; flare; landing and rollout were all accomplished. After clearing all runways both pilots made a control check of ailerons and elevator. Both pilots observed an unusual amount of free play in the roll axis up to and through about 4 degrees left and right of the null (or 0 point) on the control wheel. I did not declare an emergency and determined the safest course of action at the time was to land in these conditions with improving to good visibility and consult with maintenance at our destination. Maintenance was advised at taxi in. Maintenance log entries made. Met and debriefed verbally with maintenance tech at the gate. The duty manager was advised verbally.

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Original NASA ASRS Text

Title: B757 flight crew reported aileron movement in excess of 30 degrees was needed before an aileron response was detected. An unrelated FMC 'TIMEOUT' anomaly followed by LNAV; VNAV; autoflight; and autothrottle disconnect when either left or right navigation radio was selected.

Narrative: Event that is the subject of this report was first observed on ILS approach. Approaching the airport; we received radar vectors for the transition to the ILS approach from the approach controller. A prior event; (may or may not be related to this event); occurred about 30 minutes prior to TOD and was managed and documented with Maintenance Control. A CDU issue occurred as follows: Selecting either NAV RAD (Navigation Radio) on either CDU caused the respective FMC to 'Timeout'. Followed by a loss of LNAV; VNAV; and autothrottles. VNAV speed and cruise data were also lost in the FMC. All autoflight functions were successfully restored; route was checked and verified; and the respective FMC returned to full function without NAV RAD available. Autoflight; Autothrottles; LNAV; VNAV; all restored. Maintenance Control proposed a test: selecting both FMCs to source 'L' and retry NAV RAD. Same results as above: 'TIMEOUT' on respective side FMC where NAV RAD CDU key was selected; loss of LNAV; VNAV; autothrotte. Again; all these functions were manually reselected and restored. We were VMC at this point; prior to Top of Descent (TOD).Next we tried both FMCs source both 'R'; same results as above. Maintenance Control advised. (Dispatch advised he was monitoring our ACARS COMM with Maintenance Control). Maintenance Log entry made as per SOP. All functions; including all auto flight functions were operating from TOD through approach phase. NAV RAD was N/A on either CDU. What follows is the subject of this report. I don't know if the event below and the issue documented above are related.On approach; aircraft configuration was managed as per profile; SOP. Gear was selected prior to FAF. Flaps 20 at FAF. Inside FAF; PF observed unusual amount of control wheel displacement. Winds were relatively steady; little or no crosswind; mostly a direct headwind; reported at 10 knots. Fuel was balanced. Captured on LOC on GS; PF managing speed and flaps (Flaps 30 planned; briefed) to target values. Landed Flaps 30.Inside FAF; PF and PNF both observed left control wheel displacement of about 3-4 degrees wing down. We were IMC transitioning to VMC below a variable layer at about 500-1000 ft. Visibility was good; reported at 10 NM. Captain directed and FO confirmed; autopilot and autothrottles off for the balance of the approach. Autopilot and autothrottles were disconnected. At disconnect; PF observed and stated to the effect: 'the flight controls (in roll) were sloppy or lose' i.e.; flight controls did not feel typical for this phase/configuration. The aircraft was fully controllable. The yoke had more 'play' or 'slop' but was responsive; in all axis. The PF and PM both physically observed and verified the roll degradation from typically observed in this configuration at these speeds. We were not slow. Target was 135 KIAS. A normal approach; flare; landing and rollout were all accomplished. After clearing all runways both pilots made a control check of ailerons and elevator. Both pilots observed an unusual amount of free play in the roll axis up to and through about 4 degrees left and right of the null (or 0 point) on the control wheel. I did not declare an emergency and determined the safest course of action at the time was to land in these conditions with improving to good visibility and consult with maintenance at our destination. Maintenance was advised at taxi in. Maintenance Log entries made. Met and debriefed verbally with Maintenance tech at the gate. The Duty Manager was advised verbally.

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.