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AF447

Old 6th Jun 2009, 16:30
  #321 (permalink)  
 
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OVERTALK

Logical.
Quite similar to the high altitude departures of:

China Airlines 747
ASN Aircraft accident Boeing 747SP-09 N4522V San Fransisco, CA, USA

TU154
ASN Aircraft accident Tupolev 154M RA-85185 Donetsk

and others......
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Old 6th Jun 2009, 16:34
  #322 (permalink)  
 
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OVERTALK
Brings to mind also the loss of an RAAF 707 tanker off East Sale some ten or more years ago (although that was a VMC air exercise gone horribly wrong). The low-speed departure due to asymmetry and flight control limitations seem similar.

I imagine that a departure into autorotation of a multi-engined heavy would be non-recoverable.
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Old 6th Jun 2009, 16:35
  #323 (permalink)  
 
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Pool,

I beg to differ with you on this one:

Redundancies are here to exclude failures
If redundancies are to exclude failures, why is it a redundancy then ?
The whole concept of a redundancy is primarily based on the concept of failure. The pilot is not a system, it is liveware and not hardware such as ADRs etc etc...

The pilot carries a redundancy due to his/her Training/Experience/Skills but i am afraid that is even a more limiting factor at times...a topic in itself.

The same way redundancy is built into systems, protections must be included in the most extreme combinations of failures. I am not asking for more protections. i am asking for the same protections available under more extreme failures or comibinations of thereof.

Afterall it is FBW as you stated. So it is either a fully functioning marvellous system or a backup mode that makes you recover and fly the plane like a conventional one.
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Old 6th Jun 2009, 16:48
  #324 (permalink)  
 
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AIR FRANCE to change all pitot heads due to airspeed errors

In light of OVERTALK's explanation at post 344 of the airspeed discrepancies, wonder if Air France are just wasting their francs doing this: (i.e. I suspect that they ARE)
Air France gave a possible clue to the loss of its Flight 447 last night by announcing it was to replace a vital instrument sensor on all Airbus jets.
The memo was sent to all the airline's pilots, but the company refused to comment on it saying it was confidential.
Airbus said the move was part of the investigation into the crash that killed 228 people flying from Rio de Janeiro to Paris.
The memo said Air France has been replacing the instruments - known as pitot tubes and responsible for feeding flying speed data to the aircraft's instruments and computers. It said it will finish the task in "coming weeks".
One theory of the crash is that the pitot tubes may have iced over, giving incorrect information which then led to the plane flying too fast or slow in rough weather.
Air France orders vital components replaced on jets - World news, News - Belfasttelegraph.co.uk
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Old 6th Jun 2009, 16:49
  #325 (permalink)  
 
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Did I miss something... First message on the fault list
"ctl rud trv lim fault"
I have explained this before. The rudder travel limiter uses two airspeed inputs from ADIRUs. If they are not the same it will post a fault. It will not move.
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Old 6th Jun 2009, 17:01
  #326 (permalink)  
 
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I have explained this before. The rudder travel limiter uses two airspeed inputs from ADIRUs. If they are not the same it will post a fault. It will not move.
Sorry to disagree. Yes it will move. That is why you will get a "Use Rudder With Care" message in Status Page.
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Old 6th Jun 2009, 17:02
  #327 (permalink)  
 
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Pitot tubes on AF447 had not been replaced

Alain Bouillard, head of the French investigation, said, "They hadn't yet been replaced," referring to the pitot tubes on AF447 that Airbus had recommended be replaced on all A330 aircraft. Air France had not yet acted on the recommendation and refused to comment.

Probe: Airline did not replace instruments on 447 - Yahoo! News


“The sensors on this aircraft had not yet been replaced,” said Paul-Louis Arslanian, director of France’s Bureau d’Enquêtes et d’Analyses, known as the B.E.A.

A spokeswoman for Airbus in the United States said in an e-mail message on Saturday that the recommendation for the replacement of the Pitot tubes was “not a safety issue.”

http://www.nytimes.com/2009/06/07/wo...er=rss&emc=rss
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Old 6th Jun 2009, 17:03
  #328 (permalink)  
 
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It would appear that AF were replacing pitot tubes anyway

"In 2007, Airbus advised operators of the Airbus A330 that were equipped with Pitot tubes manufactured by the French company Thales to replace them.

Stefan Schaffrath, an Airbus spokesman, confirmed that this recommendation, known as a service bulletin was made, but said it was for reasons of improved performance rather than safety concerns.

“The advice was issued because there was a new generation of device out there with improved performance regarding its measurement capability,” Mr. Schaffrath said. “This is nothing unusual as there are constant updates ongoing throughout the life of an aircraft.”

Airbus said it had informed air safety regulators in Europe and North America about the recommendation at the time. But on Friday a spokeswoman for the Federal Aviation Administration was not able to confirm this, and said there were no plans to turn this recommendation into a requirement."

http://www.nytimes.com/2009/06/07/wo...e.html?_r=1&hp
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Old 6th Jun 2009, 17:06
  #329 (permalink)  
 
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Sorry to disagree. Yes it will move. That is why you will get a "Use Rudder With Care" message in Status Page.
I think he means the LIMITER won't move (which means the rudder has full travel).

Max
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Old 6th Jun 2009, 17:14
  #330 (permalink)  
 
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In light of OVERTALK's explanation at post 344 of the airspeed discrepancies, wonder if Air France are just wasting their francs doing this (changing pitot probes): (i.e. I suspect that they ARE)
Well, AF decided to change these probes before the accident due to previous incidents. In fact Airbus pitot probes were already redesign in the 90s as they were already involved in airspeed discreapencies while flying in heavy precipitations or freezing conditions, sometimes leading to AP/ATHR disconnections, F/CTL ADR disagree and F/CTL ALTN LAW.

This problem is basically known and documented by Airbus since 95...
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Old 6th Jun 2009, 17:14
  #331 (permalink)  
 
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I think he means the LIMITER won't move (which means the rudder has full travel).
Does that mean that the LIMITER will limit to its last valid min, max, or intermediate rudder travel ?
.
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Old 6th Jun 2009, 17:26
  #332 (permalink)  
 
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The rudder will move in response to rudder pedal movement, but the device which limits the travel at high speeds will be using the wrong speed as a reference - so you may get too much movement.

OVERTALK
You got there just before I did as I was ploughing through the pages - I was going to ask if anyone knows what the roll limits are for the IR's and ISIS, whether they have full freedom or cannot survive a 360 degree roll. Because, as BOAC alluded to earlier, how does icing make an IR fail?
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Old 6th Jun 2009, 17:32
  #333 (permalink)  
 
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Overtalks theory is most credible....what I find unreal is the temps to go from -46 to -18c in fell swoop....an incredible phoenomena in the ITCZ. An
A330 at its max alt taking weight into account has 1.3g protection.....make the outside warmer by 30c, well theres only one way your going and that is unfortunetly down re aerodynamics. God rest their poor souls faced with an impossible situation.
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Old 6th Jun 2009, 17:39
  #334 (permalink)  
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But, Bearcat, is that not what a crew would do if that SAT change hit them? Surely when you see speed reducing at thrust limit there is only one choice. Either we have yet ANOTHER 'automatics are in control and all is ok' event or something else 'hit' them (For CNN and The Daily Mail I do NOT mean a meteorite)?
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Old 6th Jun 2009, 17:45
  #335 (permalink)  
 
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Report coming in that searchers have found first victims.
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Old 6th Jun 2009, 17:53
  #336 (permalink)  
 
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AF447

Some of the messages on PFR are insignificant with reference to Maint status items..plus those covered by ATA 22..Autopilot. Signficant data appears to be air data reference disagree, fligt control alternate law and rudder travel limiter fault. The latter if both 1 and 2 RTLs are at fault could allow full rudder input thus, subject to aircraft input, overstress the vertical stabiliser. ADR disagree could be as a result of assymetric severe icing conditions. As a result of flight control altn law fault I believe that flight envelope protection may have been compromised allowing inputs to exceed safe parameters levels. So possible causes would originate through the severe weather experienced but ultimately the loss of the aircraft may be contributed by the loss of the flight envelope protection. I will emphasise that this is pure speculation having read the ACARS PFR and without reading any previous threads.
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Old 6th Jun 2009, 17:56
  #337 (permalink)  
 
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That's not exactly bad news now (if) they've focused the search. Regarding the ISIS, there are many faults possible with the device. Could it tumble? Theoretically it is a solid-state device and not prone to that, but in a severe upset anything is possible. A power interruption also may corrupt the operation of the device. I've had one fail in flight giving a generic FAULT code and a blank screen. Who knows but the engineers all the fault modes possible...
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Old 6th Jun 2009, 17:56
  #338 (permalink)  
 
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From Le Figaro

Le Figaro - Flash actu : Vol AF 447 : des corps ont été récupérés
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Old 6th Jun 2009, 18:02
  #339 (permalink)  
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Anyone know if we can confirm or chuck out the 'Warm Pool' theory from IR weather satellite images?
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Old 6th Jun 2009, 18:04
  #340 (permalink)  
 
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CNN is quoting the Brazilian Air Force with the same information.
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