Date: 202112
Local time of day: 1801-2400
Location: ZZZ.ARTCC, US
Flight conditions: Mixed
Light: Dusk
Aircraft: B737 MAX 8
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Autopilot
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Troubleshooting; Situational Awareness; Communication Breakdown
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Loss Of Aircraft Control
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Overcame Equipment Problem; Flight Crew Regained Aircraft Control; General Maintenance Action
Contributing factors: Aircraft; Procedure; Human Factors
Primary problem: Aircraft

Narrative: While descending on arrival into ZZZ1; the aircraft was passing FL240; 310 KIAS as assigned; A/P CMD B engaged; LNAV/VNAV. The aircraft rolled violently to the right before the FO (First Officer) disengaged the autopilot and recovered from the upset attitude. The aircraft uncommanded rolled to approximately 20-30 degrees angle of bank in less than a second before the FO recovered. This exact scenario was previously written up in the logbook multiple times in the preceding days and had flown one day with no associated write ups. This was our second leg with this aircraft this day. Prior to the first leg; the FO and I discussed the malfunction and possible reactions to develop a shared mental model should it occur again. After the recovery we analyzed the malfunction by observing the 'SPOILERS' annunciation illuminated. All other flight control indicators and hydraulics appeared normal. The FO continued to fly and manage radios while I ran the QRH for SPOILERS. The last step 'compute non-normal performance data-spoilers' did create confusion because we could not find 'spoilers' under the flight control non-normal performance data options.After discussion; we ran the Jammed or Obstructed Flight Controls performance data but were uncertain if this applied. After discussion and early configuration; we determined that the aircraft performed normally at approach speed with no unusual control forces. Not wanting to make the situation worse with hot brakes and after discussion with my FO; I chose a Flaps 30 landing with no other problems noted. Normal landing and taxi to the gate to meet Maintenance. Since Maintenance was notified and established communication with Maintenance Control; I did not contact Dispatch. After the fact; upon studying the procedure; I realized my error and will notify them in the future.

Callback: Reporter stated he has not had any feedback from Maintenance on the issue.  He noted that the logbook showed that in past few days several spoiler actuators had been replaced; but since the anomaly only occurred with the autopilot engaged he felt it was possible that a spoiler actuator was not the root cause; and instead was possibly autopilot related.



Synopsis: Captain reported that the while on descent to the destination airport; the aircraft rolled 30 degrees violently in less than one second. The First Officer disengaged the auto pilot and recovered from the upset attitude. The Flight Crew could discover no other issues and continued the approach to landing.