Date: 201304
Local time of day: 0001-0600
Location: ZZZ.ARTCC, US
Flight conditions: IMC
Weather elements / visibility: Rain
Light: Night
Aircraft: A300
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Climb; Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Air Data Computer
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Distraction; Workload; Troubleshooting; Confusion
Second reporter function: First Officer; Pilot Flying
Anomaly: Aircraft Equipment Problem Critical; Inflight Event / Encounter Weather / Turbulence
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Aircraft Equipment Problem Dissipated; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Returned To Departure Airport; Flight Crew Took Evasive Action; General Declared Emergency; General Maintenance Action
Contributing factors: Aircraft; Weather
Primary problem: Aircraft

Narrative: Climbing through approximately FL230 received ECAM CRT: IAS DISCREPANCY. Captain's primary IAS went to zero. Captain's STBY IAS was the same as the First Officer's PRIMARY and STBY IAS. Completed ECAM and selected ADC Number 2. Continued climbing to FL320. Passing FL290 autothrottle commanded MAX THRUST. TRP CL indicated thrust should be 1.61 EPR. Even with throttles at MAX THRUST; EPR was only 1.50. Selected ATS system off and leveled at FL320. After level off with AP/FD ON; the Altitude Alerter Horn and light began sounding and flashing. All three Altimeters indicated FL320. Flight conditions were IMC with moderate precipitation. ENG and WING A/I were on. Destination weather had wide spread TSRA and would have required an Instrument Approach. Due to the additional Altimeter and Thrust issues elected to return to the departure airport.


Second narrative: Climbing out of approximately FL240 for FL320 IMC and rain; autopilot; autothrottle; kicked off; and Number 1 Yaw Damp. Captain airspeed on his PFD went to 0 and ECAM NAV ADC AIRSPEED DISAGREE. Captain followed the ECAM and switched his ADC to my side. When we turned the autothrottle; autopilot and yaw damp back on; the throttles went to firewall but the engines were not producing the commanded thrust. Climb thrust was around 1.6 EPR and the engines were only producing around 1.4. The aircraft was not climbing very well and struggled to make FL320. Also the yaw damper kicked in almost full rudder and then kicked off again. And the Number 2 autopilot would not fly straight and level. The Altitude Alert horn also came on and would not silence even though all altimeters showed us at FL320 and center did also. The Captain then turned off all automation and began to hand fly. The destination airport was covered with TRW and rain showers and had gusty winds so we elected to return to the departure airport. We declared an emergency because of the number of systems that seemed to be affected; I called Flight Control and let them know. Descending around 17;000 feet all systems started operating normally and the approach and landing were uneventful.

Second callback: The Reporter stated that his flight instruments on ADC 2 operated normally throughout this entire event. The initial failures occurred during the climb in rain and at the time St. Elmo's fire as they diverted around a thunderstorm. The aircraft was probably in a TRW blow off. The most disconcerting event to this reporter was the fact that the engines would not produce rated thrust. They were FADEC fuel systems and so he believes should have switch to ADC 2 when the Captain selected ADC 2 for his instruments. The autopilot when reengaged meandered and maintained neither heading nor altitude accurately. He believes that more than one system was affected because of the aircraft's odd behavior. He has seen an ADC failure before and this did not look like a standard ADC failure.When Maintenance arrived at the aircraft they removed it from service because a similar previous event was in that aircraft's maintenance history. He later found out that both the Captain's pitot tube and the number 1 ADC were changed before the aircraft was returned to service.

Synopsis: An A300 climbing through FL240 apparently lost ADC Number 1 so the Captain selected ADC Number 2 but the FADEC controlled engines and autopilot did not perform normally. Maintenance changed the Left Pitot Tube and ADC Number 1.