When my A321 powers up, the lower ECAM DU shows only a diagonal white line. What does it mean and what would be the fix?

  • 4
    $\begingroup$ You have a 321, but lost the POH? And don't have a service contract? $\endgroup$
    – abelenky
    Commented Feb 16, 2019 at 18:37
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    $\begingroup$ I'm not sure why people are voting this question down: it's clear and presumably there's some sort of answer to it. Saying that "you should be able to answer this yourself" isn't particularly helpful. As for the 'don't trust what strangers on the internet say' comment, that's perfectly true but you could say the same thing about every question on this site :-) $\endgroup$
    – Pondlife
    Commented Feb 16, 2019 at 23:00
  • 3
    $\begingroup$ I never could understand why people downvote a question when the OP has a rep of 1. It seems kinda pointless, sort of in the same vein as beating a dead horse. $\endgroup$
    – BillDOe
    Commented Feb 16, 2019 at 23:59
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    $\begingroup$ @pondlife The problem with Stack Exchange engaging with this sort of maintenance question is that it's a safety issue. There will be an approved procedure documented for this particular aircraft that might differ from an apparently very similar aircraft operated by another airline. Getting it wrong could be seriously damaging to the health of hundreds of people. I wouldn't want to fly with an airline whose principle source of maintenance information is 'some bloke on the internet'. $\endgroup$ Commented Feb 17, 2019 at 2:41
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    $\begingroup$ Thanks to all that responded. As for Redd Herring or whoever this superior engineer is, why be negative? It’s a valid question and I guess when you work on aircraft you have a laptop by your side to access the maintenance manuals at all times? I did not and have only been an engineer for 48 years. I subscribe to the philosophy that there are NO STUPID QUESTIONS. $\endgroup$
    – Jim harris
    Commented Feb 17, 2019 at 19:17

1 Answer 1


Display Management Computer issue:

If a DMC fails, all information is removed from the displays it controls and replaced by a white diagonal line to indicate a working display with a failed source. ECAM will detect the failure and provide a sequence of alerts.

Due to the priority rules, the E/WD display will move to the lower DU if it was DMC1 that failed. The EIS DMC switch is used to replace the failed DMC with DMC3.


Steps to clear warning:

First select DMC #3 to isolate fault to DU or DMC. If DMC is at fault reset above associated circuit breaker for 5 seconds. If fault is with DU reset these (CAPT PFD/ND = G3/E1) (FO's PFD/ND = R3/R4) (Upper ECAM = E5) (Lower ECAM = R11).


More in the maintenance manual at AMM31-60-00-710-001. (EIS start).


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