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LATAM B773 complete electrical failure?

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LATAM B773 complete electrical failure?

Old 22nd Dec 2018, 15:21
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IF the AV Herald report is correct, and circuit breakers had tripped, I would be interested to learn whether or not the crew attempted to reset them. Back in the dark ages that was a standard troubleshooting procedure, but these days it is greatly frowned upon; so greatly in fact, that at my employer we are supposed to first contact maintenance, which for this crew obviously would have been impossible. Great job landing this crippled airplane.
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Old 22nd Dec 2018, 16:02
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Also I think the 777 has an avionics bay underneath the cockpit that has breaker panels. Would not be surprised if they put the big stuff there.
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Old 22nd Dec 2018, 17:21
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It looks like HAL 9000 took control of this airplane electrical system...Probably this is the second incident like this on a tripple. The first was MH370.
Just think about something like this in mid Atlantic.
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Old 22nd Dec 2018, 17:43
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This aircraft continued to communicate with ATC, received radar vectors and landed at the nearest suitable airport. This was nothing like MH370.
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Old 22nd Dec 2018, 17:53
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I humbly disagree: imagine something like this happen by night, in mid Ocean, beyond VHF reach, no HF, no SATCOM, no nav and ONLY BATT as electrical source. Recent developments show that even RAT wasn’t available on this LATAM event. It landed at SBCF on battery power alone.

Last edited by fullforward; 22nd Dec 2018 at 20:19.
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Old 22nd Dec 2018, 19:02
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The fault list reads like a printout of the DDG!

Given that synoptic display, I think I would be erring on the side of getting it on the ground ASAP as at the back of my mind would be the possibility of battery power only, which doesnít give you that long before youíre in a cockpit with no instrumentation at night. I canít find it in the manuals but I think the backup batteries in the flight controls are only guaranteed for 20mins...

There isnít a MAIN BATTERY DISCH advisory in that list so maybe power was getting through to the battery charger, although I wouldnít like to depend on it! Top marks to the guys for a rapid and successful diversion.
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Old 22nd Dec 2018, 20:32
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The 777 RAT includes a generator that provides electrical power - you're not dependent on the battery.
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Old 22nd Dec 2018, 20:50
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Breakers tripped in the avionics bay - now thats why we used to carry an FE,
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Old 22nd Dec 2018, 20:59
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What I’ve learned from a source directly involved in the incident, they were definitely on battery power alone at landing.
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Old 22nd Dec 2018, 21:07
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The 777 RAT includes a generator that provides electrical power - you're not dependent on the battery.
Normally I would agree but given the electrical malfunctions that were present, who could say for definite? After all, both IDGs, a backup generator and the APU generator were functional and available but unable to supply power...
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Old 22nd Dec 2018, 21:41
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Originally Posted by FullWings
After all, both IDGs, a backup generator and the APU generator were functional and available but unable to supply power...
Anyone have a photo of the electrical panel in normal operating mode?

If indeed those lines connecting the various components should be green where power is being fed, there are indeed some serious questions to be answered, including if its truly un-powered, or if its just a sensor/signalling error, or a computer/programming bug!


I found this diagram, but it just begs more questions that it answers, especially around the SATCOM being depowered..... and in this case the jettison fuel pumps being INOP.





Last edited by Dee Vee; 22nd Dec 2018 at 22:37.
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Old 22nd Dec 2018, 23:24
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Originally Posted by FullWings
Normally I would agree but given the electrical malfunctions that were present, who could say for definite? After all, both IDGs, a backup generator and the APU generator were functional and available but unable to supply power...
It's been many years since I was involved in the 777 development, but IIRC, the RAT generator fed the battery bus directly - if they still had the battery bus they would have still had the RAT generator.

DeeVee - again, a couple decades since I was involved, but based on what I remember, the only way they could have lost all main bus electrical power (with both engines running) would have been either:
latent failures in the electrical bus isolation system (there are regular maintenance checks to confirm such failures are not present), or
the crew didn't correctly follow the QRH procedures after the initiating failure.
(or possibly some combination of the two)
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Old 22nd Dec 2018, 23:33
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Outcome if it had occurred in the middle of an ETOPS? Dog of fate lift its leg on the pillar of science? Be an interesting report.
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Old 22nd Dec 2018, 23:40
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Originally Posted by fullforward
It looks like HAL 9000 took control of this airplane electrical system...Probably this is the second incident like this on a tripple. The first was MH370.
Just think about something like this in mid Atlantic.
Sorry FF. but your conspiracy theories don't hold water. Unless you can prove that the customer airphone is one of those few systems that is powered by the battery system in the event of generator or APU power interruption (when even cockpit satcom is not), your attempt to suggest that MH370 suffered a full power interruption is unavailing.
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Old 22nd Dec 2018, 23:45
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Originally Posted by megan
Be an interesting report.
At least there are no issues locating the FDR's
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Old 23rd Dec 2018, 00:29
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A design where the circuit breakers can put all power offline with no obvious way to reset them seems deficient. How does that get regulatory approval?
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Old 23rd Dec 2018, 01:45
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The incident electrical page shows Main Bat with 28 Volts and 0 Amps. If they were on Bat power only should not be there any load on the amps?
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Old 23rd Dec 2018, 02:27
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Originally Posted by The Ancient Geek
Breakers tripped in the avionics bay - now thats why we used to carry an FE,
...betcha reading that...a bunch of bean-counter knees went weak...
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Old 23rd Dec 2018, 02:38
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Originally Posted by fullforward
What Iíve learned from a source directly involved in the incident, they were definitely on battery power alone at landing.
Interesting - but the phrase "at landing" is a bit ambiguous.

It is certainly true that a RAT, as the name says, runs off ram-air pressure (airspeed) and will need some minimum airspeed (130 knots in a 767) to produce useful output. So they would have lost the RAT power at some point in the final approach or roll-out, even if it was deployed and functioning for most of the event. And been on battery power alone from that point on.
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Old 23rd Dec 2018, 04:07
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This should not have happened. Uncle Boeing is going to get more grey hair

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