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Voyager Plummets (Merged)

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Voyager Plummets (Merged)

Old 14th Feb 2014, 11:21
  #61 (permalink)  
 
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wise person - keeping lapbelt 'fastened at all times' ! - maybe that should be mandatory (except while leaving seat to go to the loo)?
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Old 14th Feb 2014, 11:48
  #62 (permalink)  

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Sorry, but I very much doubt it was "close to structural Failure".
Instantaneous -1.6g against a normal operating limit of -1g isn't a particular structural drama. Severe turbulence encounters can put unsecured occupants on the ceiling without the aircraft falling apart. Obviously very distressing for the passengers and crew but some way off from the aircraft disassembling itself.

The subsequent investigation should make for interesting reading though. I'll be interested to see what particular autoflight/component failure would allow the protection limits to be exceeded like this....

If it ain't Boeing I ain't going.......
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Old 14th Feb 2014, 12:03
  #63 (permalink)  
 
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Well, perhaps Stoppers, but this must have been a sustained negative G excursion to have achieved the pitch attitude described. Rather different to an isolated instance of turbulence.


If it ain't a Boeing 787 it ain't going to catch fire.......
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Old 14th Feb 2014, 13:19
  #64 (permalink)  
 
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I don't know about structural failure but the pilot informed us that it took two of them to get the aircraft level again. We did a kind of double dip so had a second very brief 0g.
I have nothing but praise and the greatest admiration for the pilots and cabin crew and have no doubt that they saved our lives. I can only hope that they receive the recognition that all of us believe they should get
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Old 14th Feb 2014, 13:29
  #65 (permalink)  
 
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First post here, but as a person close to the voyager project i would like to point out a few errors

1) Not sure were the 1.6 g figure is plucked out from but its not quite right

2) AFS itself is not modified, however it receives extra inputs from other black boxes fitted during the mod. However these black boxes were not powered at the time (details from voyager FCOM)

3) The MAA grounded the fleet, so therefore have no say over the civil reg A/C, however all information is being passed to the CAA/EASA

When i can say more, i will, however i will not compromise my job.
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Old 14th Feb 2014, 13:52
  #66 (permalink)  
 
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Silverstreak

Isn't it funny how, before the Voyager entered service, everyone used to say how crap the Tristar was. Now it's all of a sudden viewed as a wonder jet that could single handedly save the RAF AT fleet.
Just an observation.
BV
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Old 14th Feb 2014, 15:24
  #67 (permalink)  
 
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No Bob, it could only save the RAF widebody AT tasks and, it is the total AAR capability as of now!
TriStar is not a wonder-jet, it was under-resourced and operated in a an undersized fleet by the RAF. However, it is still a very capable airframe and, it could have provided another decade of cheap AT/AAR if a small investment had been made 15 years ago instead of spending £ Billions on FSTA.

OAP
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Old 14th Feb 2014, 18:23
  #68 (permalink)  
 
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I don't know about structural failure but the pilot informed us that it took two of them to get the aircraft level again.
How could it take both pilots to level a fly by wire aircraft, surely the side stick isn't that heavily weighted?
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Old 14th Feb 2014, 18:52
  #69 (permalink)  
 
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Well, three pilots failed to fly AF447. RIP.

OAP
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Old 14th Feb 2014, 19:06
  #70 (permalink)  
 
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oilygreasemonkey, the Voyager certainly does have a modified AFS, which incorporates 'bank angle mode', for example. The modification and installation of the
'other black boxes fitted during the mod.'
were completed in Getafé, so the Voyager's AFS is emphatically not the same as that of a 'green' Toulouse A330.

Why would it take 2 pilots? The only reason I can think of is that one pilot might have doubted whether his sidestick was functioning correctly, so might perhaps have handed over control to the other pilot?
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Old 14th Feb 2014, 19:52
  #71 (permalink)  
 
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One can only say that the BOI report will make interesting reading. I am glad all my flying was done in a mandraulic aircraft, and FBW referred to control cables!
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Old 14th Feb 2014, 20:11
  #72 (permalink)  
 
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How could it take both pilots to level a fly by wire aircraft, surely the side stick isn't that heavily weighted?

I'm only going by what the the pilot told us the following day
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Old 14th Feb 2014, 20:43
  #73 (permalink)  
 
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The A330MRTT has, as I understand it, a modified AFS whereas the 'green' civil A330 aircraft operated by AirTanker are simply normal A330-243 aircraft painted grey.
So first you say you 'as I understand it'

Then you quote something very exact

oilygreasemonkey, the Voyager certainly does have a modified AFS, which incorporates 'bank angle mode', for example.
You clearly know more then you let on.

However I still maintain the that the afs itself is not modified. The bank angle mode you refer to is indeed an extra function which is fitted to the FCU for use during aar. However it's fuction can only be used when the aircraft is in air tanker mode and the signal is generated by the modifications fitted to the mil ac and then sent to the AFS system.
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Old 15th Feb 2014, 01:25
  #74 (permalink)  
 
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haltonapp:
I am glad all my flying was done in a mandraulic aircraft, and FBW referred to control cables!
It it aint Boeing, it aint going...
Cobblers to both comments.

I used to fly a hydraulic Boeing that did the same thing on numerous occasions (not quite to the same degree). Yet another untraceable autopilot error.

Quote: "Tested, found serviceable." "Tested, found serviceable." "Tested, found serviceable." "Tested, found serviceable." "Tested, found serviceable."

The only difference being, our little problem never got into the papers. (Probably did not reach the relevant authorities either, knowing that bunch.)

.

And regards the resulting dive in this particular Airbus airtanker case, how far through MMO did the aircraft go??

And regards the excessive speed, to what degree would mach-tuck exaccerbate the dive on this type? The old Boeing appeared to have a strong desire to meet up with terra firma when it went through MMO, so what are these new fancy Airbus wings like?

Silver
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Old 15th Feb 2014, 07:05
  #75 (permalink)  
 
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oilygreasemonkey, various AFS components will have been disturbed and new wiring installed for the MRTT modification. Even just the modified FCU amounts to AFS modification - and was discussed with the AAR community well over 10 years ago now.

The KC-30A AFS modifications probably include the tailstrike prevention, AAR CG protection and RCVR FCTL modifications. Whether these software modifications are resident, but inactive in the Voyager AFS, I do not know. But the AFS cannot be considered to be identical to the 'green' aircraft.

Barring aircrew or maintenance error, an AFS software bug or some form of installation error (wiring....perhaps) seem the likely culprits.

The QF72 incident led to significant modification and additional procedures long before Voyager appeared on the scene, so it is unlikely that any parallels can be drawn with that incident.

Last edited by BEagle; 15th Feb 2014 at 08:17.
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Old 15th Feb 2014, 07:35
  #76 (permalink)  

Champagne anyone...?
 
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Keep your cobblers

I too have plenty of current experience on Boeings of various sizes thanks and yes, I've witnessed the AFDS transition into incorrect modes on the odd occasion. I have not, however, had the pleasure of seeing my aircraft transition from steady state cruise in PATH or ALT to a sudden 20 degree+ nose down descent at a rate that put people on the ceiling. Couple that with the Airbus exceeding several of it's much-vaunted protections all at once (over speed, G limits, pitch rate) I'll just refer you to my original statement.

Yes, BEags, I'd accept new-technology physical problems (lithium batteries) over weird computer controlled autoflight/flight control behaviours any day of the week.
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Old 15th Feb 2014, 07:50
  #77 (permalink)  
 
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Barring aircrew or maintenance error, an AFS software bug or some form of installation error (wiring....perhaps) seem the likely culprits.
Or weather combined with mishandling e.g. using alt as a goal gather than att following an episode of severe turbulence. BEagle, you seem to have judged already, this is not like you to be so partisan
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Old 15th Feb 2014, 08:26
  #78 (permalink)  
 
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beardy, it is you who is being judgemental, I would say. Your speculation concerning (unreported) weather / turbulence and incorrect upset recovery is entirely without substance.

StopStart, I agree that quite why such an extreme manoeuvre could have been caused, given the Airbus flight envelope protection features, is highly worrying. The QF72 incident, though similar, led to significant modification - so should have no bearing on this incident.

Presumably there'll be a Service Inquiry?
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Old 15th Feb 2014, 08:33
  #79 (permalink)  
 
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Presumably; I know the MilAAIB became involved straight away and have consulted their civilian equivalents. The first statement on the ASIMS was the consideration of an SI.
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Old 15th Feb 2014, 09:04
  #80 (permalink)  
 
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There will be a SI.
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