Brand new Etihad A340-600 damaged in Toulouse; several wounded
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And NO BRAKING ACTION AT ALL !
The main gear did not lock - it appears the nose gear did and there appears to be no turn.
There appears to be a shadow where you mark tail stike one - is this a vertical marker? see other shadows to right.
Last edited by BillS; 2nd Dec 2007 at 22:49.
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Originally Posted by BillS
The main gear did not lock
None to be seen ... ?
it appears the nose gear did and there appears to be no turn
I see the shadows, but I'm talking on the much larger mark on the ground, the one the same color the 340.
Last edited by CONF iture; 19th Dec 2007 at 23:21. Reason: typo
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Originally Posted by tubby linton
I seem to remember that the anti-skid is only active above 30kts so any braking below this speed would lead to a locked wheel.
Bernd
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What's more from that picture ...
So in yellow the initial tail strike
And in green the tail mark as forward fuselage section + left engines drift to the right on wall upper section
Also the foam shape around the aircraft makes me think that #3 ENG did not shut down right after the crash and probably produced enough thrust to displace the tail in its final position ...
Did you notice the nose gear just forward #4 ENG ?
So in yellow the initial tail strike
And in green the tail mark as forward fuselage section + left engines drift to the right on wall upper section
Also the foam shape around the aircraft makes me think that #3 ENG did not shut down right after the crash and probably produced enough thrust to displace the tail in its final position ...
Did you notice the nose gear just forward #4 ENG ?
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Originally Posted by Terry McCassey
The A345/6 has the parking brakes powered by the blue hydraulic system. The parking brake selector valve, when set, acts as a pressure reducing valve and drops the upstream pressure in the brake lines to 175 bar ( 2535 psi ), this being the pressure that holds the brakes on. The system is designed to hold the aircraft with one engine at full power provided the others are all at idle. All this of course pre-supposes that you have ample blue system pressure to start with !
Originally Posted by F4F
Actually the capacity of the brakes/tires assy being able to hold the aircraft in position at high thrust is proportional to the load of the aircraft, the capacity of the brakes, and the state of the surface (and some other minute parameters)
Originally Posted by Joetom
Normal park brake is only applied to wing gear
Originally Posted by PJ2
The park brake applies pressure only to the main gear and not the center gear ...
The brake pedals apply wheel and center gear brake pressure. The left pedal applies left main brakes plus forward center gear brakes, the right pedal applies right main brakes plus aft center gear brakes.
Given this, the main and center gear wheels would be turning even under maximum pedal deflection, just above the skid point. On-site, there would be signs of heavy braking if indeed it was applied through the pedals, but there would not be skidding.
If the park brake remained set throughout the accident sequence, the wheels would essentially be locked and not turning however.
The brake pedals apply wheel and center gear brake pressure. The left pedal applies left main brakes plus forward center gear brakes, the right pedal applies right main brakes plus aft center gear brakes.
Given this, the main and center gear wheels would be turning even under maximum pedal deflection, just above the skid point. On-site, there would be signs of heavy braking if indeed it was applied through the pedals, but there would not be skidding.
If the park brake remained set throughout the accident sequence, the wheels would essentially be locked and not turning however.
Originally Posted by Joetom
If park brake was selected on and aircraft moved forward with 4 or more wheels rotating, pressing the toe brakes would have no effect as normal brakes are not avail in said condition.
First post on that list mention 2500 PSI regarding the parking brake ... but watching at the BRAKE and ACCU PRESS indicator I cannot see anything much more than 2000 PSI with PARKING BRAKE ON ?
If I well understand, there were only 8 wheels fighting 4 engines set at about 70% N1. How possible would it be for these wheels to be turning and not skidding under a continuous PARKING BRAKE action ?
Is it possible it would not even leave any braking mark ?
Thanks for your further comments.
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gladrag,
AFAIK, at least two people were seriously injured.
As usual with this sort of thread, getting "follow-up" info is almost impossible.
But some people here do still think about what happened to them, and would have liked some more news....
In my case... I did not know any of them personally.... but they were still colleagues.
AFAIK, at least two people were seriously injured.
As usual with this sort of thread, getting "follow-up" info is almost impossible.
But some people here do still think about what happened to them, and would have liked some more news....
In my case... I did not know any of them personally.... but they were still colleagues.
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Heard from a senior insider at Toulouse "they did everything wrong, ran all 4engines at 80% max power for engine run up instead of one at a time, overloaded parking brakes, pointed the aircraft at a building instead of towards open areas, after it got away on the brakes it was allowed to run and accelerate uncorrected for 13 seconds, finally engines throttles were closed and power reduced 2 seconds prior to impact, by then it was too late - aircraft total write off police investigation continues as is standard procedure in France".
Last edited by Wizard; 25th Dec 2007 at 21:05. Reason: additions
Pilots' Pal
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Hindsight bias
In accident investigation there is a notion known as the "hindsight bias". This is the understandable inclination to say (of those involved): "Why did they do this?" or "why didn't they do that?" etc.
While an accident is evolving - all the holes are lining up - those involved do not appreciate they are involved and often take the "best" steps to resolve the situation, often falling back to "knowledge-based" rules.
Virtually every accident comprises a sequence of events; each sequence is an "opportunity" to prevent the accident - assuming you know the accident is happening.
While an accident is evolving - all the holes are lining up - those involved do not appreciate they are involved and often take the "best" steps to resolve the situation, often falling back to "knowledge-based" rules.
Virtually every accident comprises a sequence of events; each sequence is an "opportunity" to prevent the accident - assuming you know the accident is happening.
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Virtually every accident comprises a sequence of events; each sequence is an "opportunity" to prevent the accident - assuming you know the accident is happening.
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Thanks Terry for that Technical Training note, and as you said, 175 bars is about 2500 psi.
Also, from your document, I've been very interested in these other notes:
"The PRK BRK SEL VLV is operated by two (electrical) motors ..."
"It also sends an electrical signal to the BSCU and EBCU in order to inhibit other braking modes. This signal is disabled within the BSCU if blue system pressure, monitored by the pressure transducer, falls below 1450 psi."
I won't comment on these now ... but keep them on the side.
Obviously, there is something very "strange" with these 13 seconds !?
How that senior insider from Toulouse manage to squeeze 13 sec for that airplane to travel at the very most its own length knowing than 2 sec before impact the boat had already reached its cruising speed of 15 meters per second ?
Then how that senior insider from Toulouse explains the boat did not follow the crew order to turn away from the wall ? (BTW he even does not mention that ...)
And how that senior insider from Toulouse explains the absence of braking marks if "it got away on the brakes" ?
That late inconvenient picture publication is very tough on BEA credibility ... just one more time !
Thanks to forget for letting me know how to do the trick with the image.
Also, from your document, I've been very interested in these other notes:
"The PRK BRK SEL VLV is operated by two (electrical) motors ..."
"It also sends an electrical signal to the BSCU and EBCU in order to inhibit other braking modes. This signal is disabled within the BSCU if blue system pressure, monitored by the pressure transducer, falls below 1450 psi."
I won't comment on these now ... but keep them on the side.
Originally Posted by Wizard
Heard from a senior insider at Toulouse
"they did everything wrong, ran all 4engines at 80% max power for engine run up instead of one at a time, overloaded parking brakes, pointed the aircraft at a building instead of towards open areas, after it got away on the brakes it was allowed to run and accelerate uncorrected for 13 seconds, finally engines throttles were closed and power reduced 2 seconds prior to impact, by then it was too late - aircraft total write off police investigation continues as is standard procedure in France".
"they did everything wrong, ran all 4engines at 80% max power for engine run up instead of one at a time, overloaded parking brakes, pointed the aircraft at a building instead of towards open areas, after it got away on the brakes it was allowed to run and accelerate uncorrected for 13 seconds, finally engines throttles were closed and power reduced 2 seconds prior to impact, by then it was too late - aircraft total write off police investigation continues as is standard procedure in France".
Obviously, there is something very "strange" with these 13 seconds !?
How that senior insider from Toulouse manage to squeeze 13 sec for that airplane to travel at the very most its own length knowing than 2 sec before impact the boat had already reached its cruising speed of 15 meters per second ?
Then how that senior insider from Toulouse explains the boat did not follow the crew order to turn away from the wall ? (BTW he even does not mention that ...)
And how that senior insider from Toulouse explains the absence of braking marks if "it got away on the brakes" ?
That late inconvenient picture publication is very tough on BEA credibility ... just one more time !
Thanks to forget for letting me know how to do the trick with the image.
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CONF iture, Wizard,
From what information given in the snippet you posted did you get the position of the aircraft as seen in your picture? Pointing the aircraft at a structure is not the same as putting it directly in front of it. It only means that if it moves directly forward (although for an unspecified distance) it will hit that structure. The posted quote implies that it is standard procedure to point it into an open area, in this case here that would be towards south-east.
The information given was not only heard from an unnamed "senior insider", but was also in the Accident Information Telex from AI, which all A340-600 operaters will have received; cf. FCS Explorer's post from 21st November, 12:04CET. The information in said AIT was based on examinaction of the DFDR, and approved for release by the BEA.
Bernd
From what information given in the snippet you posted did you get the position of the aircraft as seen in your picture? Pointing the aircraft at a structure is not the same as putting it directly in front of it. It only means that if it moves directly forward (although for an unspecified distance) it will hit that structure. The posted quote implies that it is standard procedure to point it into an open area, in this case here that would be towards south-east.
The information given was not only heard from an unnamed "senior insider", but was also in the Accident Information Telex from AI, which all A340-600 operaters will have received; cf. FCS Explorer's post from 21st November, 12:04CET. The information in said AIT was based on examinaction of the DFDR, and approved for release by the BEA.
Bernd
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Shouldn't the FDR tell us the aircraft's heading during the static runup?
FWIW, for a performance check (called MPA once upon a time, not sure about today), setting high power (at least 50% thrust, usually) is required for a specified stabilization time of a few minutes. If this were the case at TLS, and the work crew were not aware the ship was moving, then the reason for the 11 seconds delay in retarding T/L's might be understood.
FWIW, for a performance check (called MPA once upon a time, not sure about today), setting high power (at least 50% thrust, usually) is required for a specified stabilization time of a few minutes. If this were the case at TLS, and the work crew were not aware the ship was moving, then the reason for the 11 seconds delay in retarding T/L's might be understood.
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Lowly wheel chocks use.
Maybe I am old fashioned, having been part of a 50's airforce, but has Airbus become so modern that the use of wheel chocks before an engine run-up, or even being parked, is no longer considered "cool" ?
Does full engine power cause the landing gear to "bend" and that's the reason for not using chocks?
Does full engine power cause the landing gear to "bend" and that's the reason for not using chocks?
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Yankee Whisky. The matter of wheel chocks during high power runs has been discussed here. If you were pushing chocks under your wheels then you were doing it wrong - as is half the world according to this thread 
