Narrative:

In cruise initially lost autoflt -- flight control unit 1. 25 mins later lost FCU 1 and 2. Contacted dispatch and maintenance control. Unable to restore system. Diverted to phl due to severe WX at destination area. Declared emergency and landed without incident. System lost: all FCU controls and displays. Radar, autothrust, autoplt 1 and 2, flight director 1 and 2 had partial navigation display with only raw data RMI's and ILS. Callback conversation with reporter revealed the following information: callback to reporter revealed that the aircraft was an a- 320, en route to lga airport. The postflt inspection by maintenance personnel showed a hardware problem within the FCU system. An unexpected situation developed in this event when the ECAM produced a class 2 maintenance message. This message was not within the field of training received by the flcs at this air carrier for the A-320 and masked the operational status of other equipment so that the flight crew had to flight check their navigation display system plus the autothrust system and autoflt system as well. The air carrier's maintenance and operations are now aware of this fault and are going to rewrite their maintenance and flight handbooks to indicate the possibility of this occurring and how to handle this type alert or warning associated with these failures. Supplemental information from acn 276389: in cruise at initially lost flight control unit (FCU) 1. About 25 mins later, lost both FCU's. System lost include all FCU controls, autothrust, autoplts 1 and 2, both flight directors, radar. We had raw data with only partial navigation display. We contacted company maintenance and dispatch. We were unable to restore any system. Destination WX reported large thunderstorms in the area. We declared an emergency and diverted without incident. Callback conversation with reporter revealed the following information: reporter called back and revealed that the air carrier had to replace the faulty FCU. This is a single unit that has 2 channels so that the 2 pilots might operate their navigation modes selectively and individually. There were several surprises for the flight crew in this event. One was that the WX radar ran off this FCU control unit. It had been thought that only the items needed for automatic navigation system worked off the FCU, such as ats, mode selections of LNAV/VNAV, speeds, headings, etc. Another surprise was that the checklist for the single loss of 1 channel did not offer much in a reset solution. The loss of 2 channels did and the captain remarked to the first officer after the loss of the first channel that he hoped that the other one didn't go also. It did. The third surprise was the fact that the circuit breakers had varying time limits on their 'rest' times. The circuit breakers for the FCU reset had a 7 min rest time for reset but this information was not in the pilot's operating manual. He further stated that other circuit breakers have variable rest times. Air carrier is going to make note of these times in the pilot's operating manual for checklist references. The training department has had no previous experience with a loss of both FCU unit channels and is going to make a 'loft' program out of this scenario.

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Original NASA ASRS Text

Title: ACFT EQUIP PROB CAUSES FLC TO DECLARE AN EMER AND DIVERSION TO ALTERNATE ARPT.

Narrative: IN CRUISE INITIALLY LOST AUTOFLT -- FLT CTL UNIT 1. 25 MINS LATER LOST FCU 1 AND 2. CONTACTED DISPATCH AND MAINT CTL. UNABLE TO RESTORE SYS. DIVERTED TO PHL DUE TO SEVERE WX AT DEST AREA. DECLARED EMER AND LANDED WITHOUT INCIDENT. SYS LOST: ALL FCU CTLS AND DISPLAYS. RADAR, AUTOTHRUST, AUTOPLT 1 AND 2, FLT DIRECTOR 1 AND 2 HAD PARTIAL NAV DISPLAY WITH ONLY RAW DATA RMI'S AND ILS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: CALLBACK TO RPTR REVEALED THAT THE ACFT WAS AN A- 320, ENRTE TO LGA ARPT. THE POSTFLT INSPECTION BY MAINT PERSONNEL SHOWED A HARDWARE PROB WITHIN THE FCU SYS. AN UNEXPECTED SIT DEVELOPED IN THIS EVENT WHEN THE ECAM PRODUCED A CLASS 2 MAINT MESSAGE. THIS MESSAGE WAS NOT WITHIN THE FIELD OF TRAINING RECEIVED BY THE FLCS AT THIS ACR FOR THE A-320 AND MASKED THE OPERATIONAL STATUS OF OTHER EQUIP SO THAT THE FLC HAD TO FLT CHK THEIR NAV DISPLAY SYS PLUS THE AUTOTHRUST SYS AND AUTOFLT SYS AS WELL. THE ACR'S MAINT AND OPS ARE NOW AWARE OF THIS FAULT AND ARE GOING TO REWRITE THEIR MAINT AND FLT HANDBOOKS TO INDICATE THE POSSIBILITY OF THIS OCCURRING AND HOW TO HANDLE THIS TYPE ALERT OR WARNING ASSOCIATED WITH THESE FAILURES. SUPPLEMENTAL INFO FROM ACN 276389: IN CRUISE AT INITIALLY LOST FLT CTL UNIT (FCU) 1. ABOUT 25 MINS LATER, LOST BOTH FCU'S. SYS LOST INCLUDE ALL FCU CTLS, AUTOTHRUST, AUTOPLTS 1 AND 2, BOTH FLT DIRECTORS, RADAR. WE HAD RAW DATA WITH ONLY PARTIAL NAV DISPLAY. WE CONTACTED COMPANY MAINT AND DISPATCH. WE WERE UNABLE TO RESTORE ANY SYS. DEST WX RPTED LARGE TSTMS IN THE AREA. WE DECLARED AN EMER AND DIVERTED WITHOUT INCIDENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR CALLED BACK AND REVEALED THAT THE ACR HAD TO REPLACE THE FAULTY FCU. THIS IS A SINGLE UNIT THAT HAS 2 CHANNELS SO THAT THE 2 PLTS MIGHT OPERATE THEIR NAV MODES SELECTIVELY AND INDIVIDUALLY. THERE WERE SEVERAL SURPRISES FOR THE FLC IN THIS EVENT. ONE WAS THAT THE WX RADAR RAN OFF THIS FCU CTL UNIT. IT HAD BEEN THOUGHT THAT ONLY THE ITEMS NEEDED FOR AUTO NAV SYS WORKED OFF THE FCU, SUCH AS ATS, MODE SELECTIONS OF LNAV/VNAV, SPDS, HDGS, ETC. ANOTHER SURPRISE WAS THAT THE CHKLIST FOR THE SINGLE LOSS OF 1 CHANNEL DID NOT OFFER MUCH IN A RESET SOLUTION. THE LOSS OF 2 CHANNELS DID AND THE CAPT REMARKED TO THE FO AFTER THE LOSS OF THE FIRST CHANNEL THAT HE HOPED THAT THE OTHER ONE DIDN'T GO ALSO. IT DID. THE THIRD SURPRISE WAS THE FACT THAT THE CIRCUIT BREAKERS HAD VARYING TIME LIMITS ON THEIR 'REST' TIMES. THE CIRCUIT BREAKERS FOR THE FCU RESET HAD A 7 MIN REST TIME FOR RESET BUT THIS INFO WAS NOT IN THE PLT'S OPERATING MANUAL. HE FURTHER STATED THAT OTHER CIRCUIT BREAKERS HAVE VARIABLE REST TIMES. ACR IS GOING TO MAKE NOTE OF THESE TIMES IN THE PLT'S OPERATING MANUAL FOR CHKLIST REFS. THE TRAINING DEPT HAS HAD NO PREVIOUS EXPERIENCE WITH A LOSS OF BOTH FCU UNIT CHANNELS AND IS GOING TO MAKE A 'LOFT' PROGRAM OUT OF THIS SCENARIO.

Data retrieved from NASA's ASRS site as of July 2007 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.