B737 Undifferentiated or Other Model
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Flight Crew Total 992.63; Flight Crew Type 992.63
Aircraft Equipment Problem Critical; Inflight Event / Encounter Loss Of Aircraft Control
Flight Crew Overcame Equipment Problem; Flight Crew Regained Aircraft Control
Aircraft
Started a descent from 36;000 [feet] following VNAV path with autopilot on. Aircraft was a touch high; so opened speed brakes at normal rate to detent. When retracted speed brakes at normal to slow rate; aircraft banked to 25-30 degrees to right in approximately 2 seconds. Attempted to stop bank by turning off AP; autothrottles; and rotating yoke in opposite direction. Took approximately 2 seconds to return to level flight. Continued flight without using speedbrakes. Had been a previous Maintenance write up for this; but had been closed the day before. Other flights had occurred since closing of write up. Continued on to destination.
Aircraft had a previous report of a roll to the right when retracting the speed brakes. During our descent at about FL360 and 300 kias; the First Officer; who was flying; extended the speed brakes in a very normal fashion. When he retracted the speed brakes in the same; very normal fashion; at about the mid-point of retracting them; the aircraft rolled at about 15 degrees per second to about 30 degrees right wing down. At that point; the autopilot had responded with about 60 degrees of left aileron which stopped the roll; and by this time; the First Officer's hands were on the controls which then caused the autopilot to revert to CWS mode. Then; the aircraft returned to wings level and the First Officer stowed the speed brake handle. There were no further anomalies and the remainder of the flight was unremarkable.
B737 Flight crew reported uncommanded 25-30 degree roll while retracting speedbrake. Uncommanded roll previously reported.