Narrative:

During the captain's cockpit set-up, the captain's electronic flight instrument system signal generator unit failed. The EFIS symbology became blurry and then 2 diagonal white lines appeared on the pfd and the navigation display, indicating that the instruments themselves were functioning but the signal generator unit that draws the pictures on the instruments was faulty. On the captain's switching panel, he selected 'sgu on system 3' to verify system 3 operation. An entry was made into the aircraft maintenance log stating 'captain's EFIS signal generator unit inoperative. Selected to system 3.' aircraft maintenance arrived to verify the malfunction and begin repair. Here is the first mistake the captain made. He did not stop his cockpit preparation and consult the MEL to determine the particulars of this one failure. He continued on with his cockpit preparation while the maintenance technicians were working. After an interval of time, the maintenance tech announced that the item had been deferred, presented the aircraft maintenance log to the captain, and placed an orange deferred sticker next to the 'signal generator unit on system 3' switch on the captain's switching panel. The maintenance action was recorded as follows: 'placed on MEL 31-51-01-02 ECAM signal generator unit #1 inoperative. CAT 'C' expires sep/sat/03. Control number X.' here is the second mistake the captain made. He did not specifically review the maintenance signoff to ensure that the original problem had been fixed. He read the signoff, looked at the orange sticker, and was satisfied that maintenance had done their job. Thus, the crew finished their duties, blocked out (by now 7 hours 36 mins after the captain's show time), and took off. Only when preparing to have their flight release amended after takeoff for the inoperative signal generator unit did the captain notice the error. The maintenance technician had deferred the wrong signal generator unit. The write-up specifically stated the EFIS signal generator unit: electronic flight instruments system signal generator unit. The tab for section X of the aircraft's MEL says 'flight instruments,' so I must assume that this is where the maintenance technician looked for his guidance. However, the table of contents page of section X is labeled 'indicating and recording.' there is not one single flight instrument listed in section X. They are all in section Y 'navigation.' the only signal generator unit listed in section X is for the ECAM system. I believe that the maintenance technician made an honest mistake. He was looking in the flight instruments section of the aircraft maintenance log to defer an inoperative signal generator unit. He found a signal generator unit, but it was for another system. He deferred the only signal generator unit he found in the flight instruments section and believed he had accomplished the correct task. The captain retains the ultimate responsibility here, and he did not do his job. 1) the captain did not cease his cockpit preparation and consult the MEL when this problem arose. (He will in the future.) he should have determined if the aircraft was up or down with the #1 EFIS signal generator unit inoperative: it was not. He should have told maintenance this when they arrived. 2) the captain did not ensure that the maintenance performed matched up with the problem that had been written up. (He will in the future.) 3) the air carrier MEL was no help to the maintenance technician in this case. As an aside, on the return leg of this flight, the left half of the captain's navigation display failed during preflight. He stopped his cockpit setup, consulted the MEL, wrote up the discrepancy, and notified maintenance. Once they were finished, he reviewed their signoff, reviewed the MEL, amended his flight release, then departed on the flight. Old dogs can indeed learn new tricks!

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Original NASA ASRS Text

Title: A310 CREW HAD THE LCL MECH DEFER THE WRONG SIGNAL GENERATOR UNIT.

Narrative: DURING THE CAPT'S COCKPIT SET-UP, THE CAPT'S ELECTRONIC FLT INST SYS SIGNAL GENERATOR UNIT FAILED. THE EFIS SYMBOLOGY BECAME BLURRY AND THEN 2 DIAGONAL WHITE LINES APPEARED ON THE PFD AND THE NAV DISPLAY, INDICATING THAT THE INSTS THEMSELVES WERE FUNCTIONING BUT THE SIGNAL GENERATOR UNIT THAT DRAWS THE PICTURES ON THE INSTS WAS FAULTY. ON THE CAPT'S SWITCHING PANEL, HE SELECTED 'SGU ON SYS 3' TO VERIFY SYS 3 OP. AN ENTRY WAS MADE INTO THE ACFT MAINT LOG STATING 'CAPT'S EFIS SIGNAL GENERATOR UNIT INOP. SELECTED TO SYS 3.' ACFT MAINT ARRIVED TO VERIFY THE MALFUNCTION AND BEGIN REPAIR. HERE IS THE FIRST MISTAKE THE CAPT MADE. HE DID NOT STOP HIS COCKPIT PREPARATION AND CONSULT THE MEL TO DETERMINE THE PARTICULARS OF THIS ONE FAILURE. HE CONTINUED ON WITH HIS COCKPIT PREPARATION WHILE THE MAINT TECHNICIANS WERE WORKING. AFTER AN INTERVAL OF TIME, THE MAINT TECH ANNOUNCED THAT THE ITEM HAD BEEN DEFERRED, PRESENTED THE ACFT MAINT LOG TO THE CAPT, AND PLACED AN ORANGE DEFERRED STICKER NEXT TO THE 'SIGNAL GENERATOR UNIT ON SYS 3' SWITCH ON THE CAPT'S SWITCHING PANEL. THE MAINT ACTION WAS RECORDED AS FOLLOWS: 'PLACED ON MEL 31-51-01-02 ECAM SIGNAL GENERATOR UNIT #1 INOP. CAT 'C' EXPIRES SEP/SAT/03. CTL NUMBER X.' HERE IS THE SECOND MISTAKE THE CAPT MADE. HE DID NOT SPECIFICALLY REVIEW THE MAINT SIGNOFF TO ENSURE THAT THE ORIGINAL PROB HAD BEEN FIXED. HE READ THE SIGNOFF, LOOKED AT THE ORANGE STICKER, AND WAS SATISFIED THAT MAINT HAD DONE THEIR JOB. THUS, THE CREW FINISHED THEIR DUTIES, BLOCKED OUT (BY NOW 7 HRS 36 MINS AFTER THE CAPT'S SHOW TIME), AND TOOK OFF. ONLY WHEN PREPARING TO HAVE THEIR FLT RELEASE AMENDED AFTER TKOF FOR THE INOP SIGNAL GENERATOR UNIT DID THE CAPT NOTICE THE ERROR. THE MAINT TECHNICIAN HAD DEFERRED THE WRONG SIGNAL GENERATOR UNIT. THE WRITE-UP SPECIFICALLY STATED THE EFIS SIGNAL GENERATOR UNIT: ELECTRONIC FLT INSTS SYS SIGNAL GENERATOR UNIT. THE TAB FOR SECTION X OF THE ACFT'S MEL SAYS 'FLT INSTS,' SO I MUST ASSUME THAT THIS IS WHERE THE MAINT TECHNICIAN LOOKED FOR HIS GUIDANCE. HOWEVER, THE TABLE OF CONTENTS PAGE OF SECTION X IS LABELED 'INDICATING AND RECORDING.' THERE IS NOT ONE SINGLE FLT INST LISTED IN SECTION X. THEY ARE ALL IN SECTION Y 'NAV.' THE ONLY SIGNAL GENERATOR UNIT LISTED IN SECTION X IS FOR THE ECAM SYS. I BELIEVE THAT THE MAINT TECHNICIAN MADE AN HONEST MISTAKE. HE WAS LOOKING IN THE FLT INSTS SECTION OF THE ACFT MAINT LOG TO DEFER AN INOP SIGNAL GENERATOR UNIT. HE FOUND A SIGNAL GENERATOR UNIT, BUT IT WAS FOR ANOTHER SYS. HE DEFERRED THE ONLY SIGNAL GENERATOR UNIT HE FOUND IN THE FLT INSTS SECTION AND BELIEVED HE HAD ACCOMPLISHED THE CORRECT TASK. THE CAPT RETAINS THE ULTIMATE RESPONSIBILITY HERE, AND HE DID NOT DO HIS JOB. 1) THE CAPT DID NOT CEASE HIS COCKPIT PREPARATION AND CONSULT THE MEL WHEN THIS PROB AROSE. (HE WILL IN THE FUTURE.) HE SHOULD HAVE DETERMINED IF THE ACFT WAS UP OR DOWN WITH THE #1 EFIS SIGNAL GENERATOR UNIT INOP: IT WAS NOT. HE SHOULD HAVE TOLD MAINT THIS WHEN THEY ARRIVED. 2) THE CAPT DID NOT ENSURE THAT THE MAINT PERFORMED MATCHED UP WITH THE PROB THAT HAD BEEN WRITTEN UP. (HE WILL IN THE FUTURE.) 3) THE ACR MEL WAS NO HELP TO THE MAINT TECHNICIAN IN THIS CASE. AS AN ASIDE, ON THE RETURN LEG OF THIS FLT, THE L HALF OF THE CAPT'S NAV DISPLAY FAILED DURING PREFLT. HE STOPPED HIS COCKPIT SETUP, CONSULTED THE MEL, WROTE UP THE DISCREPANCY, AND NOTIFIED MAINT. ONCE THEY WERE FINISHED, HE REVIEWED THEIR SIGNOFF, REVIEWED THE MEL, AMENDED HIS FLT RELEASE, THEN DEPARTED ON THE FLT. OLD DOGS CAN INDEED LEARN NEW TRICKS!

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.