Air carrier flight crew reported ADC failure inflight causing temporary aircraft loss of control.
Synopsis
Air carrier flight crew reported ADC failure inflight causing temporary aircraft loss of control.
Narrative
Captain was Pilot Flying with autopilot on at cruising altitude of FL330. The aircraft suddenly went into a dive and heard loud overspeed warning indicator aural. Captain said his airspeed decreased and was indicating around 70 kts. My airspeed was about 10 kts into the zipper; an overspeed. Captain said he had a bad ADC and transferred me the controls; he then selected ADC 2 on switching panel to agree with my speed. At this point; the aircraft lost 400 ft. When I took control of the aircraft; it was in an overspeed state and nose down pitch. I asked the Captain to tell ATC that we need lower and a block altitude. He notified ATC and also let them know of our malfunction. ATC gave us a block altitude between FL300 & FL280. As I continued to descend; the speed wasn't bleeding off as quickly as I liked and I slowed the descent rate down to reduce the airspeed. At this point; I realized our auto throttles were also INOP. So I reduced the power and called for the unreliable airspeed checklist. The Captain read me the proper pitch and power setting for the descent configuration. I flew those pitch and power settings. I arrested the descent at FL290; then turned the auto pilot back on and the airplane held altitude; and I adjusted thrust to maintain proper airspeed. Captain then ran ECAMS and QRH and we concluded that ADC 1 had failed and with it the auto throttle system; the FADEC system; fuel CG transfer system; and yaw damper had also failed with it. We then requested a climb up to FL330 and completed the flight with out further incidents.The cause of this event was due to an aircraft malfunction. This aircraft was written up for the exact same malfunction on the prior flight. If Maintenance may have been able to diagnose and fix the malfunction correctly then it may not have happened. We knew about the write up and even had one of the previous pilots jumpseat on our flight and he explained it to us. The only I think we as pilots could have done differently is that we should have had the number 2 autopilot engaged instead of the number 1 autopilot; that way; when the ADC 1 failed it; wouldn't have affected the aircraft state.
Second reporter narrative
Flying at FL330 Captain PF (Pilot Flying) on autopilot 1. ADC 1 computer failed. Yaw damper 1 and auto throttles disconnected and Captain's airspeed indicator was at about 70 kts indicated. Autopilot started to nose over to stay on speed. I handed jet to FO (First Officer) as his air data seemed accurate. Through the noise of all the warnings going off; we noticed airplane descending and speeding up into the overspeed zipper. FO adjusted power and I told Center we are descending and need a lower altitude. He cleared us immediately and was kind enough to give us a block altitude of FL280 to FL300; we chose FL290. FO did an outstanding job getting everything under control on speed; on altitude; and on his autopilot. Used unreliable airspeed checklist. Next; we went through QRH. Yaw damp 1 was off; N1 faulted and had to set to alternate per ECAM; Captain ADC to number 2; and auto throttles off. Yaw damp and auto throttles wouldn't reengage. Writing this due to descent prior to clearance; but they gave quickly plus ATC gave us priority handling for a few minutes. No emergency declaration and back to normal altitude once all under control. ATC was very helpful and accommodating. Thank you. Nice team work.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.