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A320 Emer Elec short before v1

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A320 Emer Elec short before v1

Old 11th Mar 2018, 06:28
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Question A320 Emer Elec short before v1

Hello friends,

that Scenario is often briefed: a total electrical failure (emer elec) before v1.

in case we abort the takeoff: what can we expect, what are the big Players? is the reverse working?

in case of go? what are the indications left?

Thanks so much!

SW
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Old 11th Mar 2018, 07:04
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Need a bloody good reason to stop. And a long runway.
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Old 11th Mar 2018, 07:14
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Speedwiner, if you brief this scenario then you really should know the answers to your questions.
By all means ask others for their views, but definitive information from an open forum may not very reliable, or difficult to judge.

You should have access to the relevant technical manuals and operating procedures; ask your captain to explain the briefing, seek advice from instructors, and consider using the simulator.
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Old 11th Mar 2018, 07:15
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You’ve read the FCTM and FCOM sections covering this? Do you have the OLB to input some numbers?

The table in the FCOM lays out exactly which systems you will have, and the FCTM talks through the problem as well.

Which part of the manuals is causing the problem?
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Old 11th Mar 2018, 11:33
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Have a look at the UK AAIB accident report 8//2000 G-OOAB which will give you some insight into stopping from close to V1 at max weight (in the middle of the night).
You brief what exactly you are going to stop for and then you must stick to that.
It would be a great one to run in the sim. The big one would be Antiskid?
Cheers
mcdhu
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Old 11th Mar 2018, 14:54
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You should continue even if it's scary as hell as you will lose all EFIS for few very long seconds. I practiced in the sim last year during my upgrade and that's what I was told.
Since you have no reverser, only alternate braking without antiskid, only 2 spoilers per wing, you will most likely overrun if you decide to abort.
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Old 11th Mar 2018, 15:24
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This one is not easy nor that straight forward. ASDR doesn't take into consideration reverse but yes anti skid. New aircraft the brake pressure is automatically controlled at 1000psi. The decision to go is based on the assumption that everything will work as it should in the air. With gear down aircraft will be in direct law. With only ELAC1 and SEC1 should anything happen further it is scary. I won't blame if any one went for reject.
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Old 11th Mar 2018, 19:29
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If all screens go blank momentarily just before V1 almost all pilots would abort by reflex, I guess. The briefing item would be "Loss of AC power before V1", right? It takes a few seconds for the systems to come back online after a loss of AC power and during that time frame almost everyone would abort.

I have never, nor have I heard, anyone brief this possible scenario.
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Old 12th Mar 2018, 07:23
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I would hope not. If the screens go momentarily blank you don't even know if you're below V1 or above. One can rotate with a look outside or on the ISIS, but just aborting because you're startled is a very dangerous thing.

Actually had that happen at one time in the past, however, that was a simple signal generator failure on my side, not something as serious as emergency elec configuration on the bus.
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Old 12th Mar 2018, 17:17
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I did it on my last sim. You're in for a shock if you don't have a long enough runway! As stated above, you won't have reversers; if on a later MSN you will have auto regulation of the brake pressure, if not, easy on the brakes! Takes a damn long time to stop and mind you, we did it on a 3800m long runway (although at 8300 ft high).

As pointed also by others, it's quite a shocker (since you normally don't brief for that one, so you don't know what signs to look for). Everything just goes dark, you lose all screens and it even goes a bit quiet (after the gens cut off-line!). A reject will be what most would do, out of pure startle I think. Might not work on a short runway + high speed...

Would this one fit under "unambiguous indications that the aircraft will not fly safely"? As vilas pointed out, the go decision would be made under the assumption that everything will work fine after the longest seconds in aviation history. It should fly safely, but...
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Old 13th Mar 2018, 00:12
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Nobody briefs about such multiple failures in takeoff briefing. There are any number of messed up rejects without such complications. More items you add more chances of screwing it up. Despite this briefing some may reject after the startle beyond V1. For such a major failure out of nowhere it is safer to drift of the runway end at slower speed than land up in mechanical backup in the air.
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Old 13th Mar 2018, 02:41
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It is a bit like discussing how to drink from a broken glass. No successful outcome possible, and time ... gone, to say the least.

According to AFM and FCOM, it is clearly a STOP decision.

Speedwinner: when you say "Scenario is often briefed" what do you mean by that?
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Old 13th Mar 2018, 08:15
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This particular failure scenario is a fancy of some TRE. Simulators don't kill but real life could be a bitch. First near V1 you don't have the time to find out what has happened. It is dangerous to assume the screens will be back. With ELAC2, SEC2 gone all it needs is loss of Blue hydraulic to put you in mechanical backup. RAT malfunction would give you that. Would you prefer to crash during landing in mechanical backup at approach speed or trickle out of the runway end at lower speed after a reject?

Last edited by vilas; 13th Mar 2018 at 08:29.
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Old 13th Mar 2018, 14:05
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I would prefer to have options. Airbourne, even on the stby instruments, with the gear coming up gives options. Off the side or end of the runway gives no options at all.
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Old 13th Mar 2018, 14:59
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vilas, you argue logically for balanced risk, but this view, and as with other posters’ views, assumes that the situation is known - understood, clearcut, etc.

Assumptions such as these are a weakness in simulation training - incorrect focus on testing the crew in managing an unusual situation, or even biasing decisions against a ‘go’ mentality above V1. Whereas the real learning value is in recognising unusual situations and relating them to an appropriate course of action, particularly where associated with surprise - sound, vibration, blank screens, ...

Regulators and manufacturers will have both the information and time to judge unique situations and recommend safety procedures. Crews should not be expected to identify and relate the complexity of the situation during take off; stop/go situations need to be a simple binary choice.
In many instances with time critical situations generic failures may be assumed. Failures with clear warnings can be separated - fire bell, but less clear situations are often grouped by collector alerts and action e.g. any high priority caution before V1, then stop. Don’t try to rethink many hours of design and regulation deliberation into the 1-2 sec before V1.

Similar considerations should be applied to forum debates where the design/regulatory details may be unknown.
Is this situation really ‘often’ briefed ?
What is the probability of occurrence, what other aspects might be assumed; why is the question being asked?
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Old 16th Mar 2018, 03:03
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Not once have I briefed/been briefed on this failure on a line flight. I agree stop/go decisions should be as easily made as possible; TBH we had this failure on the sim which is dark and the engine/ambient noises are a bit muffled so the startle factor by mere absence/diminishment of other clues was greater. I imagine taking off at night would create a greater startle factor than at daytime, but I'm not sure and I don't want to find out either. Losing all screens at once means something really wrong has happened and there's no time to diagnose what else is wrong. Given with little time to decide I'd make a case for a "positive indication the aircraft won't fly safely"; if before V1 you'll possibly go off the end but hopefully you'll be going slow enough... Making a go decision with limited time/information about such a critical and unusual scenario (i.e. You most certainly won't know exactly what's gone wrong) makes me cringe a little bit.

Plus I don't know what's the failure possibility (to deploy/ engage) of something that's virtually never used. I assume it's tested on some check in the life of the aircraft, but...
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Old 18th Mar 2018, 23:52
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This warning is inhibited from 80Kts until Lift Off...
It's not recommended to reject the take-off as you will lost all reversers/ Spoilers 1 2 and 5 and Normal braking.
In that case you will not have enough runway length to stop safely.

Better to get airbone with you Stanbby Instrument, retract the gear.
You will stay in Alternate Law (Not really hard to fly the aircraft in such configuration).
As soon as the RAT is deployed you will recover PDF1 ND1 and Upper ECAM, enough to manage the flight and come back on a long runway to stop the plane.
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Old 19th Mar 2018, 12:46
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If the rat doesn't deploy you go in mechanical backup. Have you done approach and landing in mechanical backup?
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Old 19th Mar 2018, 13:37
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vilas
If the rat doesn't deploy you go in mechanical backup.
Why?

According to QRH, you don't loose all 5 fly-by-wire computers or both elevators or total loss of ailerons and spoilers if the RAT doesn't deploy. You'll have "BAT Only" power available (until it runs flat).
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Old 19th Mar 2018, 14:35
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Originally Posted by vilas
If the rat doesn't deploy you go in mechanical backup. Have you done approach and landing in mechanical backup?
That is a difficult way of arguing in itself, because it includes the premise that any other redundancy might not work either. So why not abort a takeoff after a V1 cut? After all, the other engine might stop working soon after as well and then you are even worse off.

Yes, the RAT isn't used every flight, unlike both engines. And yes, that does not instill confidence that it works. However, as a last ditch redundancy barrier we have to believe airbus that it does not fail. Same as all other redundancy barriers we do have on that plane.

And to answer your question, yes, mechanical backup was not part of the official syllabus in my typerating, but we trained it nevertheless in the simulator. As far as i know it hasn't happened in real life yet.
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