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AF447

Old 6th Jun 2009, 05:39
  #261 (permalink)  
 
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ADIRU Fail

The ADIRU are compartmentalized to be fault tolerant
The message describing an Air Data ADIRU failure is different from An RLG Ring [email protected] Gyro failure, The failure of Air data either input or calculation does not preclude the Inertial portion of the ADIRU from giving correct attitude data
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Old 6th Jun 2009, 06:26
  #262 (permalink)  
Final 3 Greens
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PJ2

I am a PPL/airline pax, so please treat this comment as an uninformed question, from someone with no relevant aviation knowledge, being upfront about that.

If the groundspeed at ORARO is true, due you think there is any possibility could have been tornadic activity?

I remember well the F28 that encountered a tornado in the Netherlands and broke up middair.

Please don't be irriated if the met info or other reasons make this unlikley/impossible, my only interest in this is as a frequent passenger on this a/c type and whether this accident was a 'one off.' I am not passing an opinion, just asking a question.

Perhaps we will never know.
 
Old 6th Jun 2009, 06:37
  #263 (permalink)  
 
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For 330 pilots...

I apologise if someone has already mentioned this but it's a struggle keeping up withall the posts...
I read somewhere on the net of an Airbus bulletin a few years back about possible air data inaccuracies in the case of radome failure. Can anyone shed any light on this?

If bad weather / lightning strike was a possible cause and it did take a exceptional strike on the radome leading its structural failure, then with the disturbed airflow to the pitot probes/adm's that might have caused the inaccuracies, plus no weather radar and at that altitude and speed debris might well of gone down both engines leading to not only unreliable air data indications but also engine thrust problems / failure leading to electrical power tripping off.

In this day and age of GPS, ACARS, satelite monitoring and IT, i really do hope that the investigators find the FDR/CVR and do get to the bottom of this as there may be implications to operation of all aircraft types through out the world.
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Old 6th Jun 2009, 06:43
  #264 (permalink)  
 
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@Final3greens

Tornadic activity will not be seen at that altitude, anyway over water we would talk about waterspouts and with the water temperatures we can't completely exclude the presence of a waterspout in these highly active zones, but a waterspout will very, very, likely not have been the cause for whatever happened in the sky as long as we happen to believe that the accident took place at FL300+.
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Old 6th Jun 2009, 06:47
  #265 (permalink)  
 
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On the A332 we had the ISIS fail on shut down of both engines on ground, as soon at the NBPT (no break power transfer) kicked in from the APU generator.

Ping went the C/B of the ISIS on the ECAM.

Outstation engineer was unable to repair and dispatched us according to MEL back to base. After getting the gear up on departure, we had another ping on the ECAM, ISIS standby battery C/B popped and so we continued back to to base.

More than enough engineers to receive the aircraft with new parts in hand.

I had never seen this before, but the ISIS was a dead duck in under a second!
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Old 6th Jun 2009, 06:59
  #266 (permalink)  
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Final 3 Greens - I think weatherdude answered your question really well.

The "300kt" groundspeed value could be explained by the degradation of either the aircraft or the aircraft systems/sensors but we can't say.
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Old 6th Jun 2009, 07:14
  #267 (permalink)  
 
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Quite simply the A/C encountered Severe turbulence causing the autopilot to disconnect, normal procedure is to disconnect the autothrust and fly the aircraft manually.

There is a strong probability that the aircraft suffered a bombardment of hailstones if the severity of the CB's reported in the area are anything to go by which could cause engine failure.

This would account for the loss of the electrical system and eventual loss of cabin pressure as indicated by the ACARS messages sent.

With the amount of static in the area a mayday call on HF would be useless but to be honest with everything going on and severe vibration I doubt whether you could find the button.

With only backup for flight controls i.e manual rudder control and pitch trim, stabilised flight or recovery would be almost impossible with structual failure almost inevitable.
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Old 6th Jun 2009, 07:23
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FlyingOW

I think it was the AeroPeru B752 accident in '96 that led to Boeing introducing the Unreliable Airspeed Memory Items & checklist (the checklist already existed when I did my initial back in 2004)
Sorry, perhaps I should have made it clearer. Boeing did not provide unreliable airspeed QRH specifically for B777 before the Malaysian upset (2005). They deemed the ADIRU set up so sophisticated that unreliable airspeed could not occur. B777 upset report

You are probably correct for the B757/B767 and the older generation of aircraft.
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Old 6th Jun 2009, 07:39
  #269 (permalink)  
 
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ISIS reset

ISIS on this case doesn't fail , just reporting bad input.
The fact you quote is that ISIS need a reset after a quite long operating, but now it's over, we don't have to reset ISIS CB after that time.
from my own, and as the data I've got message related to ISIS means no data from Stby probes ....
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Old 6th Jun 2009, 07:41
  #270 (permalink)  
 
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1) In the event of an ADR 1+2+3 Fault or any combination therin , they would have got only a single chime master caution(amber) , if it was an Overspeed warning VMO + 4 KTS OR MMO +.006 They would have got a Master Warning CRC(RED) , however in either case there would have been ECAM actions to perform and in the 1st case there would be certainly some AIR DATA switching involved , as you might have already guessed there is a LOT of redundancy built in , so I do not believe that faulty speed crap for a minute .

2) In a 3 Crew operation as is always the case the relief guy would have been resting during this mishap , and unless there was a SIGNIFICANT flight upset and or if the guys upfront called for him he would not have been on deck at that point .

3) As I mentioned in the previous thread this was more than one or an isolated event that brought it down
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Old 6th Jun 2009, 07:43
  #271 (permalink)  
 
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<<With the amount of static in the area a mayday call on HF would be useless >>

Static interference may well have caused bad intereference to the aircraft receiver, but surely pilots are trained to transmit "blind" in an emergency? An HF transmission could have been heard thousands of miles away where interference might have been minimal.
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Old 6th Jun 2009, 07:47
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Multiple causal factors?
Weather
ADIRU failure. Note the nose pitch down with the Qantas incident.
MEDIA RELEASE : 14 October 2008 - Qantas Airbus A330 accident Media Conference
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Old 6th Jun 2009, 07:52
  #273 (permalink)  
 
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Being an Airbus Pilot myself, i feel very bad for the pilots of AF447.

It is highly probable the crew found themselves in a very furious and complex situation with not enough time to analyze and react properly.

Speaking from own experience, most pilot abilities are significantly reduced in moments of severe turbulence and violent shaking as well as heavy percipitation hampering the fuselage/ cockpit windows.

I realy hope the CVR/FDR are recovered, we all stand to learn a great deal from this tragedy.

Without wanting this to divert into an Airbus conception philosophy debate.

Given the protections/stabilities available in normal law being lost in so little time and all the redundancies possibly failing. Maybe It is time for Airbus to reconsider the fact that when redundancies are lost, only then, Pilots will be in dire need for protections to kick in.

My humble little contribution.
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Old 6th Jun 2009, 08:02
  #274 (permalink)  
 
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Unhappy

(Not a 330 man but) If they'd had a serious electrical failure, possibly with both AC busses off, HF would be lost, and possibly the weather radar. They may well have blundered into a cell whilst distracted with a major procedure.
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Old 6th Jun 2009, 08:12
  #275 (permalink)  
 
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BEA press conference

Hi,

Right now, a BEA press conference is broadcast on France 24 TV channel.
I'm in no way competent in such mattters. If skilled members of this forum could watch it they might gather useful info.

Cheers
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Old 6th Jun 2009, 08:19
  #276 (permalink)  
 
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Early vs late models

Originally Posted by greenspinner View Post
ISIS on this case doesn't fail , just reporting bad input.
The fact you quote is that ISIS need a reset after a quite long operating, but now it's over, we don't have to reset ISIS CB after that time.
from my own, and as the data I've got message related to ISIS means no data from Stby probes ....
Greenspinner, you appear to have a keen understanding of the latest builds of the A330's. Let me ask you this: Does the newer ISIS system have it's own pitot & static pressure transducers or is this supplied by one of the three ADR units?

Also, please tell me that the 'ISIS' artificial horizon is indeed a gyro?
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Old 6th Jun 2009, 08:29
  #277 (permalink)  
 
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2) In a 3 Crew operation as is always the case the relief guy would have been resting during this mishap
I feel differently about this. Do you have some information to substantiate this? The AF SOP for example. Otherwise, I would tend to believe that the "Relief Pilot" would probably be in a pilot seat during this time on a flight of this duration.
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Old 6th Jun 2009, 08:34
  #278 (permalink)  
 
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Maybe It is time for Airbus to reconsider the fact that when redundancies are lost, only then, Pilots will be in dire need for protections to kick in.
Interesting, and quite true. Especially these days when we're seeing lessor levels of general flying experience in the airplanes then we did in years past.
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Old 6th Jun 2009, 08:35
  #279 (permalink)  
 
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To isis speculator's

From the AMM, I never create nothing, but I know how to use it !!!
ISIS Indicator

The ISIS indicator is supplied with 28VDC from:
-
the ESS BUS (403PP) first, (when the aircraft electrical network is energized)


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and the HOT BUS (701PP), when the speed detected by the ADIRUs 1 and/or 3 is more than 50Kts.

In case of loss of the ESS BUS, the ISIS indicator is supplied only from the HOT BUS (701PP) through the ESS BUS SPLY GND/FLT COND relay (7PC).

Consumption of the equipment is 20 W maximum.

Transparency time for the ISIS indicator is not less than 50 ms (memorizing of current configuration on power supply transients comprised between 50 and 200 ms).

The display is lost during power supply cutoff comprised between 50 and 200 ms.



Thought, ISIS never failed,is just reported conditiond & situation after an unthinkable event........

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Old 6th Jun 2009, 08:39
  #280 (permalink)  
 
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ISIS

vapilot2004
Quote
Let me ask you this: Does the newer ISIS system have it's own pitot & static pressure transducers or is this supplied by one of the three ADR units?

Also, please tell me that the 'ISIS' artificial horizon is indeed a gyro?

Yes ISIS has a separate Input independent of ADIRU & Yes it has its own internal Fibre Optic Gyro (FOG)
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