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AF447

Old 13th Jun 2009, 12:48
  #1361 (permalink)  
 
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In flight break up

Although a different aircraft, the leaked Adam Air loss of control CVR can give us some idea of how fast a Jet upset will take. Do not listen to this tape unless you have a strong stomach. It very sobering. It's authenticity is disputed, however, it matches exactly the accident sequence discussed on the Adam Air thread at PPRuNe. Start it about 2/3 through. The cricket sound on Boeing is the overspeed Mach warning (crowding supersonic.) The key event is the audible "bank angle" heard over the cockpit speakers. This would be an excessive bank over thirty degrees at high altitude. From that warning, and the subsequent overbank and dive, it takes 50 seconds before the airframe fails with a small crackle followed by a loud thump (likely main wing spar failure). Then 20 secs of disintegration. The increased wind noise (louder than barberpole) in the background is something I've never heard before in a jet. And never want to.

YouTube - Takbir Pilot Adam Air

The reason for posting the link, is so you can have some kind of idea just how dangerous it is to loose either flight controls or flight instruments at night. Also you can see why a lot of us suspect a dive followed by a break up at mid-altitude before sea level.

CC

Last edited by Captain-Crunch; 13th Jun 2009 at 13:09.
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Old 13th Jun 2009, 12:50
  #1362 (permalink)  
 
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RWA
My question was, could the fact that (as far as I can tell from the transcripts) the ACARS (sorry for the acronym ) messages appear to have come in batches about one minute apart mean that the aeroplane was bucking about a fair bit and the aircraft antenna kept 'losing its line' and having to line up and' re-connect again?
I am sure others may have mentioned this before, but it is probably worth mentioning again, that the timestamps on the ACARS messages relate to the event time and rather than the transmission time over the satellite. The messages may indeed be batched if they have the same transmission priority and the interval between batches will depend of the data rate the A/C is using (600, 1200 or 10,500 bps). From the incomplete data that I have seen, it is clear that SATCOMS transmissions are regular and consistent with an A/C that is tracking the satellite reasonably well up to the last transmission at 02:14
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Old 13th Jun 2009, 13:07
  #1363 (permalink)  
 
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I'm not sure we can assume that water bottles would rupture on depressurization. They handle the pressure drop from sea level to 8000 feet (about 4PSI) without any obvious stress. 8000 to 30,000 feet is about another 7PSI. It's by no means unlikley that the bottles that can handle 4 PSI differential would rupture 11. But it's not self evident either.

In fact, if you've ever made a "rocket" from a 2-liter soda bottle, you'd know you can pump several atmoshperes of air into it with a bicycle pump without rupture.
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Old 13th Jun 2009, 13:16
  #1364 (permalink)  
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[quote] "From the incomplete data that I have seen, it is clear that SATCOMS transmissions are regular and consistent with an A/C that is tracking the satellite reasonably well up to the last transmission at 02:14."/QUOTE]

Many thanks, Dan Air UK. Can I take it that your opinion (as someone who genuinely knows a lot about satellite communication) and mine (as no more than a 1960s 'seat of the pants' light aeroplane pilot) largely coincide?

That the aeroplane was under reasonable control (flightpath-wise) for plus or minus four minutes. And then 'blacked out' - among other things, losing all communication with the satellite. Suggesting either a catastrophic systems failure or an 'Extreme Flight Path Irregularity' - like the aeroplane standing on its nose and heading for the deck at Mach. speed?
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Old 13th Jun 2009, 13:27
  #1365 (permalink)  
 
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RWA Everything depends on the provenance of the ACARS copy and the lack of additional similar information. If the transmission terminated at the top of page two, and there is no more, it would tend to support a theory similar to yours. 'Absence' of evidence is not 'Evidence' of absence. The data is proprietary, AF has behaved 'erratically' (my term) in this event.
Who knows?
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Old 13th Jun 2009, 14:25
  #1366 (permalink)  
 
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In fact, if you've ever made a "rocket" from a 2-liter soda bottle, you'd know you can pump several atmoshperes of air into it with a bicycle pump without rupture.
Good point Chu-Chu. Looked it up, the 2-liter soda bottles are good to 50 psi.
Cabin differential pressure at 35k ft is 9 psi. Can't be as confident as before, but those clear water bottles in the photo are more flimsy than the 2-litter ones. Might do a little experiment in the hangar later.
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Old 13th Jun 2009, 14:31
  #1367 (permalink)  
 
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The other 'news' is that (since the FDRs of the time recorded pedal movement and rudder movement, but were not able to 'say' whether the pedals moved the rudder or vice versa) AA587 may well not have been pilot error at all.
1) I find that very hard to believe... low frequency flutter on powreed controls?

2) If true, then where are the ADs? A very serious problem indeed with immense ramifications, which surely couldn't be covered up - requiring fundamental control system redesign.

1) & 2) taken together make it sound more of a conspiracy theory - so solid evidence please
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Old 13th Jun 2009, 15:07
  #1368 (permalink)  
 
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RE those jumpseats and the pharm box

Something that has to be considered now is the simple failure of the aft pressure bulkhead as in JAL123. That could certainly knock the tail section off.

-drl
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Old 13th Jun 2009, 15:19
  #1369 (permalink)  
 
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In particular, the vertical stabiliser is missing from the items being displayed. Simply because it has not yet made it to land or was it withheld from the display for some reason?

http://www.pprune.org/4994299-post1367.html
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Old 13th Jun 2009, 15:34
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Debris - crew seats

As far as I am aware, no cabin seats are attached to the aft bulkhead. In my opinion the seats photographed may have come from the front face of the right-side aft galley or from a left-hand partition such as at door 2 or 3. I do not know the precise AFR configuration for cabin attendant seats.
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Old 13th Jun 2009, 15:40
  #1371 (permalink)  
 
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General seating chart for an AF 332:
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Old 13th Jun 2009, 15:46
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Debris - crew seats

... or door 2 rh but probably not door 3 lh.
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Old 13th Jun 2009, 16:07
  #1373 (permalink)  
RWA
 
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1
) I find that very hard to believe... low frequency flutter on powreed controls?

2) If true, then where are the ADs? A very serious problem indeed with immense ramifications, which surely couldn't be covered up - requiring fundamental control system redesign.

1) & 2) taken together make it sound more of a conspiracy theory - so solid evidence please
I'm sure that no offence was intended, Harry Mann. Nor was any percepted. But I'm not in the habit of telling lies, or even 'inaccuracies', on the Net or anywhere else. And I'm sure that you feel exactly the same.

The rudder controls on AA587 were conventionally-linked. No Airbus-style FBW..........

Please read this whole NTSB report through. And then get back to me, and we can have a fully-informed discussion.

NTSB Abstract AAR-04/04

Last edited by RWA; 13th Jun 2009 at 16:34.
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Old 13th Jun 2009, 16:11
  #1374 (permalink)  
 
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Rob21,
Interesting point. I all my many years of transatlantic crossing it has always been difficult to get 2 particular carriers to talk on 123,45 on 128.95 to discuss anything pertinent, ie, turbulence, or levels they will be requesting for onward planning purposes.
Those carriers are Air France and Lufthansa.
Don't know why...and this is my personal experience only. I always thought it to be because I am a pom!
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Old 13th Jun 2009, 16:16
  #1375 (permalink)  
 
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Other flights in the area

As previously reported, there were indeed other airplanes nearby, even in the same route.

Closest one was Iberia IB6024 (A340-300) which took off 7 minutes after the AF to a (geographically) similar destination on the same route. They briefly saluted and chatted with the AF crew while getting the flight ready earlier in the airport.

Press reports IB pilot declaring: "We flew about 10 minutes (~80 miles) directly behind the AF, at 35000'... being monitored by TCAS, noticed bad weather ahead and decided to deviate from it an unscheduled 30 miles to the east at about the same time the AF dissapeared from the radar forever..." They never had visual contact. They never picked up any transmissions from the AF around the time the accident is believed to have happened in any of the open frequencies.

He heard the repeated attempts of brasilian traffic controllers to contact the AF after its dissapearance from radars all the way to the entrance to Senegal air space". Iberia flight was totally uneventful otherwise, with nothing unusual about the weather etc (except that there were indeed patches of bad weather around the area at around that time worthit of circunvention).

Last edited by justme69; 13th Jun 2009 at 16:29.
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Old 13th Jun 2009, 16:49
  #1376 (permalink)  
 
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Originally Posted by justme69
Press reports IB pilot declaring: "We flew about 10 minutes (~80 miles) directly behind the AF, at 35000'... being monitored by TCAS, noticed bad weather ahead and decided to deviate from it an unscheduled 30 miles to the east at about the same time the AF dissapeared from the radar forever..."
Maximum range for the TCAS to display a target is only 40 NM ...
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Old 13th Jun 2009, 18:16
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"Maximum range for the TCAS to display a target is only 40 NM ..."

The airline I fly for has five A330s (sn 800s and 900s) that show TCAS targets up to about eighty miles ahead and about twenty behind.
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Old 13th Jun 2009, 18:30
  #1378 (permalink)  
 
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Hi RWA

At the risk of being completely wrong...

I don't think that the rudder would feedback force to the pedals. Even in a non FBW plane this big the controls are moved by hydraulic actuators. The pedal force feel is artificially generated (by the artificial feel box or Q-feel box) which simply converts a pedal position and dynamic pressure into a force.

On another point about composites, when I was at Airbus working on VTP structures we always used hot/wet testing (both heat and moisture degrade composite structural properties). I don't know about the fatigue work as I wasn't involved but I don't think it would have been done differently. Thats not the same as fluid getting into a sandwich structure, as with the rudder failures, which is a more serious problem.
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Old 13th Jun 2009, 18:31
  #1379 (permalink)  
 
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Ok, I didn't know that.
But I'm not sure that the IB A-343 are that new ?
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Old 13th Jun 2009, 19:14
  #1380 (permalink)  

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The twin jumpseats are located
-FWD, near L1
-AFT, at the far end of the back galley. You could say they mark the end of the cabin.
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