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LATAM B773 complete electrical failure?

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LATAM B773 complete electrical failure?

Old 7th Jan 2019, 00:08
  #81 (permalink)  
 
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Is that not what the existing system is expected to achieve, by isolating the faulty element?
I still do not understand what actually went wrong in this instance, the generators were green, but the distribution was on strike for some reason.
Turning off the generators might have helped, but it also might have left the system entirely powerless.
Think the crew performed splendidly and hope that the investigation is equally effective.
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Old 7th Jan 2019, 16:38
  #82 (permalink)  
 
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I vaguely remember an incident back in the late 90’s on one of our 777s. They were minding their own business in the cruise when they stated getting EICAS advisories for lesser-known utilities. This turned quite rapidly into cautions, with many of the aircraft’s electrically powered systems going off line, to the point that it was looking pretty serious. I can’t recall how they got most of them back but the root cause was established later as being an ELMS failure. Interesting as it was still functioning but had a problem with some kind of feedback, so was load shedding on the basis of too much demand but carried on until it had turned off everything it could...
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Old 8th Jan 2019, 04:03
  #83 (permalink)  
 
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So there is a precedent. Was it determined what the root cause was for the ELMS to go haywire in that case?
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Old 8th Jan 2019, 04:39
  #84 (permalink)  
 
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ELMS Integrity

If indeed It is found to be a cascading ELMS failure is there merit in considering a software fix where ELMS is duplicated in the same way as the INS which is effectively "refereed" in many modern designs?
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Old 9th Jan 2019, 00:11
  #85 (permalink)  
 
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So far as I understand they lost both main AC busses. They did have generators available (there’s a picture of the system synoptic somewhere by the beginning of the post) but nowhere to connect them. Given the scenario, I don’t think that your suggestion would have made any difference. Hell even the RAT apparently didn’t engage to a bus! Is that bit of info confirmed? Usually the RAT feeds an essential bus or something different from the main busses. Having the RAT deployed but not powering its bus(ses) would be a true kick the nuts... Electrical system should’ve gone completely bat sh*t crazy somehow for this to happen
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Old 9th Jan 2019, 03:38
  #86 (permalink)  
 
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Escape Path, everyone is entitled to their opinion but:
Originally Posted by belfrybat
According to the commander, interviewed on TV, power came back after the engines were shut down. Presumably from the APU, on the footage the cabin lights were visible.
I'm leaning to the interpretation that the RAT dropped off on approach due to low airspeed at that point, but that it was energizing the appropriate DC busses until the approach. Otherwise, it seems the batteries would have been exhausted before the opportunity for the approach.

Is there even a switch or contactor that would even be able to shut down the RAT power once extended?

In any case, If I encountered such a problem inflight in mid-Ocean that was not covered in emergency procedures, training, or whatever, I would not just sit there wringing my hands.
This is not any form of criticism of the LATAM crew, who did an absolutely marvelous job. Didn't even flat spot the tires it seems.
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Old 9th Jan 2019, 18:41
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So there is a precedent. Was it determined what the root cause was for the ELMS to go haywire in that case?
Can’t remember precisely - could have been something to do with load sensing? The net effect, as described above, was load shedding irrespective of the actual draw from the systems.

The LATAM incident sounds a little bit different as most of the busses went off, taking down what was attached to them, as opposed to commanded de-powering of selected units...
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Old 20th Jan 2019, 16:14
  #88 (permalink)  
 
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So I support one of my first posts on this thread - sort of HAL 9000 took control of this 777 electrical system. Surprise such a serious and disturbing event generated few discussion.
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Old 20th Jan 2019, 20:02
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Not much to discuss until the forensics is done and a report is published. I spoke with a 777 test pilot yesterday and he hadn't heard about this incident. Cards are being played very close to the chest on this one.
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Old 24th Jan 2019, 13:35
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The only reason you haven’t seen much discussion is because people rarely make meaningful replies to random speculation.

I’m as curious as the next person to find out why this happened, but I’m putting your “computer became self aware and tried to kill the crew” theory near the bottom of the list of possible causes. Isn’t this supposed to be a forum for professional pilots?
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Old 26th Jan 2019, 06:35
  #91 (permalink)  
 
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I'm on the belief that people using this forum are educated enough to realize or at least suspect some statements are metaphoric...I bet you know I made an analogy to an AIMS or EMLS failure, for that matter.

Last edited by fullforward; 29th Jan 2019 at 15:03.
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Old 26th Jan 2019, 20:25
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Remember 11 years or so back, a Qantas B744 landing in Bangkok on battery power? In the end it came down to a drain in one of the galleys flooding an electrical compartment. I predict that, like that incident, the hindsight is going to be strong when they get to the root cause of this one.
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Old 2nd Feb 2019, 13:38
  #93 (permalink)  
 
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Am surprised there have not been any further developments in this case. It seems a serious enough failure that one would expect an urgent inquiry.
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Old 2nd Feb 2019, 20:40
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No first hand knowledge here (but a lot of experience in the Boeing safety program). I know this won't be a popular opinion around here, but the apparent lack of urgency (or even news) suggests crew error - the crew failed to properly follow an established procedure or checklist in response to a relatively minor problem. As I recall, that was the case on the Qantas 747 event mentioned previously.
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Old 2nd Feb 2019, 23:44
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Crew error was not a factor in the Qantas B747 event at BKK:

ATSB TRANSPORT SAFETY REPORT Aviation Occurrence Investigation – AO-2008-003 Final

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Old 7th Apr 2019, 18:49
  #96 (permalink)  
 
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Any more news on this incident?
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Old 29th May 2019, 16:54
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Avherald posted this update

On May 24th 2019 Brazil's CENIPA released a brief update that they found evidence of a short on connector D7232 which connects the right hand backup generator to the right hand converter. The backup converter responded by opening 4 connectors feeding the transfer busses (two transfer bus breakers and two converter circuit breakers).​​​​​​
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Old 9th Aug 2021, 14:10
  #98 (permalink)  
 
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The final report on this incident was published on 8th July 2021 (IG-190/CENIPA/2018), although it references only the aircraft PT-MUG and not the flight number. Both the airmanship of the pilots, and the subsequent electrical fault tracing and analysis are wonderous to behold.

Followers of the "777X Woes" thread might find much of interest.

The fault cascade is somewhat beyond by understanding, particularly the relevance of the fault in the permanent magnet generator. But taking the report's conclusion as correct, are the recommendations not somewhat thin?

Surely an examination of a sample of the failed connectors in other 777s would have been merited, at least?
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Old 9th Aug 2021, 16:11
  #99 (permalink)  
 
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Downloadable reports, in Portuguese and English, available here:

CENIPA - Relatórios Finais
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Old 10th Aug 2021, 11:55
  #100 (permalink)  
 
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The aircraft Commander had 29,000 hours, 45 years in aviation? Remarkable.
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