Air carrier pilot reported loss of multiple systems while in cruise. Flight crew advised ATC and ret...

Attributes
ACN	1620823
Time
Date	201902
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZZ.ARTCC
State Reference	FO
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Person 1
Function	Captain
Qualification	Flight Crew Instrument Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Speed All Types Inflight Event / Encounter Other / Unknown

Narrative:

In cruise at FL300; with a previous malfunction causing the loss of hydraulic system 3; the aircraft had a FCC [flight control computer] 2b and a deu [display electronic unit] #2 failure. The failures caused the autopilot to disengage; the throttles to retard to idle and the airspeed envelope to close causing an over speed warning. Pilot flying immediately lowered the nose and advanced the throttles to prevent a stall condition. Aircraft lost approximately 1;000 feet prior to the pilot returning aircraft to its assigned altitude. Notified ATC of the situation and ran appropriate checklist to recover systems. We then requested clearance to return to ZZZ. On return; we [advised ATC] and dumped approximately 65;000 lbs. Of [fuel] to bring aircraft below maximum landing weight. Captain made an uneventful landing to runway xxr; we then proceeded to taxi aircraft to the [company] ramp. Loss of multiple systems; FCC 2b; deu (display electronic unit) #2; hyd (hydraulic) #3 with multiple secondary alerts.

Original NASA ASRS Text

Title: Air carrier pilot reported loss of multiple systems while in cruise. Flight crew advised ATC and returned to departure airport.

Narrative: In cruise at FL300; with a previous malfunction causing the loss of hydraulic system 3; the aircraft had a FCC [Flight Control Computer] 2b and a DEU [Display Electronic Unit] #2 failure. The failures caused the autopilot to disengage; the throttles to retard to idle and the airspeed envelope to close causing an over speed warning. Pilot Flying immediately lowered the nose and advanced the throttles to prevent a stall condition. Aircraft lost approximately 1;000 feet prior to the pilot returning aircraft to its assigned altitude. Notified ATC of the situation and ran appropriate checklist to recover systems. We then requested clearance to return to ZZZ. On return; we [advised ATC] and dumped approximately 65;000 lbs. of [fuel] to bring aircraft below maximum landing weight. Captain made an uneventful landing to Runway XXR; we then proceeded to taxi aircraft to the [Company] ramp. Loss of multiple systems; FCC 2b; DEU (Display Electronic Unit) #2; Hyd (Hydraulic) #3 with multiple secondary alerts.

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.