***don't read this thread if you don't wanna know what I wanna show***
Hi all,
For those of you who are interested in aviation safety, I hope you find this of interest.
I posted a thread about AF447 a couple of weeks ago. In that thread I pointed out a comment made by some guy who reminded us (aircraft enthusiasts) about a vertical Stab (tail fin) failure with a previous Airbus incident.
Now it's not official, but I want to show you something very striking. I don't believe that the vertical fin failed in an excessive yaw maneuver (as in the case of the pervious incident), the stab on AF447, to my observation, failed not in a yaw, but from VNE+ air loads.
If you look at image AF447 10, the schematic, note the three structural mounting points of the vert stab to the empennage. Now in image AF447 1&2, note that the forward mount has sheared, and the second and third mount did not fail, but have torn away the structural bulkhead within the empennage itself. Also, note in the series of images that the leading edge of the vert stab has no damage from debris hitting it whatsoever, yet the lower rear of the rudder has been crushed. This allows us to suggest that the vert stab was torn away from the empennage along the longitudinal axis, pulled rearward with the top rotating aft.
These are strong indicators that the vert stab failed BEFORE the aircraft broke up and well before impact with the water. From the age and flying hours of the airframe, I can only envisage this was due to dynamic air loads, exceeding, by at least 30%, the aircraft's VNE (velocity never exceed). If true, it is possible that uncorrectable yawing into excessive air loads may have caused the fuselage structural failure aft of the wings.
Note the wreckage, in particular the crew [jump] seats, still in good order, without impact damage, and still sprung up in the closed position. Internal, cosmetic panels such as overhead locker doors, although torn off, have little if any impact damage. In one image, the entire galley section is in one piece, stowage containers and all!
This seems to have all the hallmarks of a fly-by-wire [flight computer] failure.
If you Google AF447 and go down 5 links, you will see a link which posts the same article that I posted here about two weeks ago; a weather analysis for AF447. This is looking to be a vital piece of the puzzle. Some of the comments, based upon first hand experience from retired commercial airline pilots, about ice formation, are quite compelling. http://www.weathergraphics.com/tim/af447/
Most aircraft incidents have their twists and turns, but I feel AF447 might well show us issues which most thought impossible.
So it wasn't the necessarily the weather or a lightening strike that caused the accident then, as strongly stated in the previous thread?
Good to hear of reasonable the progression of the investigation. Especially important was the recent finding of the beeps of the black boxes, so at least there is a possibility of such grand-scale human tragedy as in this example with the aircraft doesn't happen again.
So it wasn't the necessarily the weather or a lightening strike that caused the accident then, as strongly stated in the previous thread?
Good to hear of reasonable the progression of the investigation. Especially important was the recent finding of the beeps of the black boxes, so at least there is a possibility of such grand-scale human tragedy as in this example with the aircraft doesn't happen again.
Actually the circumstantial information points to ice formation in environments where it was previously thought not possible. So it still seems to be weather related, or at least contributed. The information in the previous thread, pertaining to the alerts of AC and DC systems failures, as well as flight computer and associated hardware anomalies, suggests some sort of electrical influence, even fire (fire and explosion has almost been ruled out from debris evidence though).
The Black Box signals have since proven to be a false alarm. This leaves very little time to run signal sweeps. The tug which is sensing the signal, can only cover 13km (squared I think) per [24hr] day. Then it's searching by braille unfortunately.
If I had to guess, and luckily I don't in an official sense (thank God), I feel we're looking at some unusual series of events, something we haven't see before. Ice formation in the pitot tubes could have given false or sparadic airspeed indications (data supports this), storm cell and turbulence, although not severe in its own right, could cause many false inputs and disorientations. Engine failure under certain icing conditions could easily create big [assymetric] issues. The biggest indicator is the flight computer, its hissy-fit and reverting to semi-manual control says something about the perameters it failed to deal with.
My guess, as unusual as it sounds, is ice formation, as rare as it is at that altitude, it has been reported and severe. It possibly confused the computer by giving high and low airspeed inputs, the plane m have unnecessarily 'hunted' on the [elevator] trims, pitching uncontrollably, it may have given up and stepped down to [semi] pilot control. It may even have retarded or advanced the throttles, in the worse case, advancing the throttles in a dive, but with false low air speed inputs or vice versa. Disorientated, the pilots may have perpetuated the error, trusting the false airspeed low indications.
Failure of all PRIMS and SECS was not evident in the ACARS downlink.
Of course Peter. I realise the Prim and Sec were operational, I was referring to the stepping down of control [Law]. Do you know if this is normal procedure if parameters are exceeded, ie. airspeed high low fluctuations but nominal static air pressure?
BTW, what did you think of the stab pics? From an engineering perspective, that's got me intrigued.
By virtue of the fact the airframe was not confetti (and whole bodies have been recovered) the break-up was indeed in-flight.
The vertical stabilizer damage while interesting does not concern me as much as the ISIS system also having failed along with the ADIRS as well as one PRIM and SEC.
One can only hope they recover the DFDR as it is clear multiple systems failed possibly not even giving a direct law option.
Thanks for the wording Peter, there's heaps of engineering info on the net.
"Applying an unreliable airspeed memory item would have proven to be very difficult because of the violent shaking and opening a QRH for an ADR check procedure even less likely." http://blogs.crikey.com.au/planetalk...bus-operators/
I remember a simple 20sec procedure taking me forever in turbulence. Hmmm.
"Applying an unreliable airspeed memory item would have proven to be very difficult because of the violent shaking and opening a QRH for an ADR check procedure even less likely."
Mark
Sorry you don't use the QRH to action phase ones or memory items...that's why they are called memory items!
This makes me wonder about the credibility of the source/blog....seems highly speculative. Ever since a 767 went in (due unreliable airspeed) off the coast of south America close to a decade ago this procedure has been drilled by most operators.
If you look at image AF447 10, the schematic, note the three structural mounting points of the vert stab to the empennage. Now in image AF447 1&2, note that the forward mount has sheared, and the second and third mount did not fail, but have torn away the structural bulkhead within the empennage itself. Also, note in the series of images that the leading edge of the vert stab has no damage from debris hitting it whatsoever, yet the lower rear of the rudder has been crushed. This allows us to suggest that the vert stab was torn away from the empennage along the longitudinal axis, pulled rearward with the top rotating aft.
These are strong indicators that the vert stab failed BEFORE the aircraft broke up and well before impact with the water. From the age and flying hours of the airframe, I can only envisage this was due to dynamic air loads, exceeding, by at least 30%, the aircraft's VNE (velocity never exceed). If true, it is possible that uncorrectable yawing into excessive air loads may have caused the fuselage structural failure aft of the wings.
Note the wreckage, in particular the crew [jump] seats, still in good order, without impact damage, and still sprung up in the closed position. Internal, cosmetic panels such as overhead locker doors, although torn off, have little if any impact damage. In one image, the entire galley section is in one piece, stowage containers and all!
This seems to have all the hallmarks of a fly-by-wire [flight computer] failure.
August 2008 - Air Caraibes Atlantique
Paris to Martinique
Plane flying through turbulence experiences failure of autopilot, ADIRU and computerised instruments. Pilots successfully fight to restore control.
September 2008 - Air Caraibes Atlantique
Paris to Martinique
Second Air Caraibes flight to Martinique has identical experience. Plane is same model, different aircraft.
October 7, 2008 - Qantas Flight 72
Singapore to Perth
Makes emergency landing after twice plunging uncontrollably in flight following failure of ADIRU, autopilot and instruments. 64 injured, 14 seriously.
December 28, 2008 - Qantas Flight 71
Perth to Singapore
Forced to return to base after failure of autopilot and ADIRU. Different aircraft, same model as in previous incident.
May 21, 2009 - TAM Flight 8901
Miami to Sao Paulo
Experiences failure of autopilot, ADIRU and instruments. Crew regain control after five minutes. No injuries.
US investigation under way.
June 1, 2009 - Air France Flight 447
Rio to Paris
Crashes during Atlantic storm, killing 228. Automatic radio messages indicate that in minutes before crash, crew lost autopilot, ADIRU and computerised instruments.
June 23, 2009 - Northwest Airlines
Hong Kong to Tokyo
Flight loses autopilot, ADIRU and instruments before landing safely. US investigation under way.
