tech synthesis AF447
 

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AF447 : the probes issues targeted since 2008
Although the debate is not authorized until the BEA will decide to talk about the probes issue, and in response to many questions we have received from around the world, we believe it would be useful to clarify a few points.
The operator and manufacturer state that they have «recently discovered» a malfunction with the Pitot probes. They claim they have been working very hard towards finding a solution and state that it is only recently that solutions have been found. We hold a document that may hold a strong indication of the contrary. The problem might have been acknowledged way before the accident. This document has been provided to us from a well known website that our readers are familiar with. We have often turned towards this web site to seek answers to our questions : type http://forfaiture.freeservers.com, tech notes 3 & 4 in your web browser.
This "Technical Note" comes from Air France and seems to be an authentic document. We audited the origins, dates, and metadata contained in the original file. We have confirmation that this document was valid, validated, and still current as at 31 May 2009. No one had heard from the plane and no one could have imagined that the plane was never going to land in Roissy and yet this document had been printed out, that same day, in order to advise the tech team on the ramp to get ready to change some probes on the aircraft’s arrival.
This paper could demonstrate several things:

• 'We' were already aware of what the problem was the morning of the accident (the famous erroneous airspeed). There are passed records that display the exact ACARS messages sent by the AF477. The same causes had already produced the same effects. It is likely that the AF447 experienced the same problems as all the other aircraft that encountered a Pitot defect, the only difference being that those other aircraft managed to free themselves from that situation.
• The BEA's communications through the media have raised questions. We believe that the families of the victims have been left in confusion, dragging in despair all that has been said in the press. In the end, we feel that an explanation of the origin of the accident might be dramatically simpler.
• At the date of this document (file made in June 2008, note dated August 2008), it is written that there had already been 6 cases that had produced the same alarms. The Pitot probes were designated undoubtedly as the cause of these problems (the french version of this note is slightly different than its english translation) : "At the time of creation of the NT, a case on THT and six cases on A340 AFR have been reported. " (THT is Air Tahiti Nui, who’s aircraft are maintained by Air France). On june the the 19th, M. Gourgeon (CEO of Air France) stated on RTL (a french radio) that there had never been an incident "before August 2008". How are we to qualify this statement?
• It is also written that Airbus was aware of the problem at the date stated in the above: "Investigations conducted on Airbus family aircraft showed that most of airspeed discrepancy events were due to Pitot water ingress and to probe draining holes obstructed by external particles. Another hypothesis is in study on a possible saturation of pitots by crystallized ice in high flight level."
• It is written that the probes type BA have solved the problems: "The new pitot probe corrects the problems with enhanced water trap and relocated drain holes."
• It is written that "the operational impact" is "NIL" (nil (nihil) = not applicable): how can we imagine that there is no operational impact after the loss of so many vital systems and informations? Who are the pilots or services involved in flight safety that validated this unbearable assertion?
• It is even considered to be a "corrective action", but only under certain circumstances, that of which the breakdown occurs first on the plane ... permitting the installation of "a new standard pitot PN: C16195BA"

Reading the documents from summer 2008 show an official awareness of the problem and a technical note was therefore created. Unfortunately, this also shows the solution to the problem was official, it had been written but never taken care of. By August 2008, 6 different problems had already existed in Air France. Why did Air Caraïbes decided to change its probes in September 2008, a month after it's first warning, while others with the same problems simply did nothing?

We, like the BEA, have almost approached a conclusion. What we need now is to understand why our colleagues flying the AF477 were unable to get the aircraft out of the mess. After consulting the pilots that have been faced with these same Pitot issues, we realize that a large amount of immediate judgement is needed to overcome the multiple alarms, in a very little time. The cockpit crew must execute long check-lists and procedures, complex and even somewhow contradictory... By night, in manual flight, without any speed reference, with the probable loss of attitude, and partial stand-by instruments... Only a donkey could state in public that a simple hold of «pitch and power» could be enough to solve the problem.
There have been 35 worldwide reported cases of this Pitot probes issue, including 9 this year. The AF447 flight could have become the 36th case on the list, and it became the first case that never made it back home.
The day that entering in a cloud will be held as the main reason for 35 different cases of serious A330 / A340 incidents will be the day that we will possibly imagine that the AF477 represented the 36th case. On that day, we will ask Mr Feldzer his opinion on the clouds.
One last important thing that we must do : in order to let you compare the events experienced by the flight AF447 with those described in the technical note mentioned above, we would like to expose the actual list of the contents of the famous ACARS messages sent by the plane. In order to keep our sources secret, we have transformed the appearance of the original file, but the content has remained exactly the same.
There are of course the alarms and warnings mentioned in the Air france technical note.
This Pitot probes issue is the strongest to date.
And it is the most carefully avoided by officials.
No doubt it’s a coincidence ... NOTE: the order of faults and warnings represented here is not consistent with the chronology as experienced on the flight AF447. We are rebuilding this "probable chronology" with specialists, the representation attached is a view sorted as it would be done by the «Airman» software.
publié le 2009-06-24 20:03 par EuroCockpit.