Tech Log The very best in practical technical discussion on the web

AF447

Old 8th Jun 2009, 19:08
  #661 (permalink)  
 
Join Date: Dec 2007
Location: Cornwall-on-Hudson, New York
Posts: 876
Likes: 0
Received 0 Likes on 0 Posts
If the aircraft entered the water in "a steep dive," I doubt they'd be finding intact bodies, of which they've currently recovered something like 16.

Last edited by stepwilk; 8th Jun 2009 at 20:47.
stepwilk is offline  
Old 8th Jun 2009, 19:15
  #662 (permalink)  
 
Join Date: Feb 2006
Location: Ireland
Age: 52
Posts: 115
Likes: 0
Received 0 Likes on 0 Posts
Andy S - you’re not the only one
Unfortunately, this thread is decaying into utter chaos again. Someone mentioned before that it was starting to look like Airliners. Net. Personally, at times, I think this looks worse than the equivalent there.

This, inspite of numerous warnings from the MODS – and also from other Pruners (i.e. PJ2 and Rainboe, for example. )
In the eight pages growth while I slept, there is precisely nothing new or even interesting; what I read is manufactured, regurgitated (because someone was too lazy to read the thread - the Vazquez presentation is cited at least five times) or picked out of thin air.

The thread is bulging with explanations to the newly-curious about why in many cases their wild notions about what happened are wrong.
PJ2 really hit the nail on the head concerning the regurgitating of the same stuff again and again ad nauseum. Such as repeated postings of “the original acars list”, “the ‘updated’ acars list” or Tim Vasquez’s Meteorological analysis . (something around 15 times between 2 threads).
The thread title is AF447 – NOT ‘BASIC Meteorology for student PPL’s 101 or BASIC principles of flight for the uninitiated.

What I find intringuinly is why this forum is banning pilots who weekly fly the leg SouthAmerica - Europe on AB330/340 and knows very well what they are talkin´ about...
Would that be referring, in part at least, to the numbties who needed to be told what pressure altitude means, or possibly what the relationship defining MACH number is, or even why it had to be a b*m* because it dropped off’ radar and wasn’t squawking 7700(!!!!)????

However, be aware that from now on, any posts with content that is considered by the moderators to be based on un-attributed sources or more importantly theories from anyone without a proper understanding of LH, heavy metal flying will be deleted and the poster banned from the thread for future posting. We will decide on who has a realistic understanding of those criteria by reading what is posted and using our own experience as current airline pilots and crew who do LH flying on heavy metal.
mods

I made my first post on the subject of AF447 - about the use rad altimeters as back up - about 10 minutes ago. . . .. . . . Its was removed. What is going on here?


For new people, who just won't bother to read the whole thread (and I know it is long,) or who don't have time, a good summary of what we've been covering is here: (and you should read it!)
Captain Crunch – Not a bad job at all. Interesting to note that despite the caution concerning constant change and a ‘story’ that is rapidly evolving– there are a couple of folks there (I think aptly might be referred to as wiki editor pedants) who object(esp on grounds of ‘original research’) while managing to demonstrate a lack of relevant knowledge akin to some of those posting drivel here while trying to masquerade as pilots or aviation related pros.

Also apparent lack of damage on the side and leading edge has some implications but I don't intend to be the first one to write it down on the PPRuNe.
I think I know what your getting at – but I wouldn’t see what you say as being indicative either way just yet. Of course, I hope (forlornly) that the speculators won’t start off………..wasted hope – me thinks! Nonetheless – we’ve already had – It’s the full vertical stabilizer……it isn’t ……it is……it isn’t………


Scriabh – I’m not an airbus expert – but if you ask on the Tech forum, I’m sure some of the Airbus types would be happy to explain.
theamrad is offline  
Old 8th Jun 2009, 19:15
  #663 (permalink)  
 
Join Date: Mar 2009
Location: Abu Dhabi
Age: 65
Posts: 2
Likes: 0
Received 0 Likes on 0 Posts
Couple of years ago over Indian Ocean flew into a bubble of warm air, (just a whisper of cirrus clouds), A342 stopped flying and had to descent 4000' into clear air. About 15-20 min later temp recovered and were able to climb back to FL370.

On the other side, FL410 over the Alpes 18 months ago, light A346 (close to TOD), TAT decreased for 15 degrees and a barber pole just jumped down, leaving us with overspeed warning for 10-15 seconds, thrust on idle, just sitting there and enjoying the horn. Clear air.

In 15 yeras of long range flying happened to me twice. Although not common, sudden temperature variations are possible.


Closer to subject, third pilot was not present in the cockpit at that time for sure - somebody mentioned that he might have been sending ACARS massages. Third pilot (or a pilot) was in the bunk at that time, 4 hrs into the flight, and probably unable to reach the cockpit at all. Could have been captain himself, as far as we know.
flyer58 is offline  
Old 8th Jun 2009, 19:17
  #664 (permalink)  
 
Join Date: Apr 2009
Location: Petaluma
Posts: 330
Likes: 0
Received 0 Likes on 0 Posts
Without Rudder deflection limit at M.80 and with power available to deflect it, the assembly (Rudder and Vertical Stabiliser) would have parted the fuselage, given sufficient angle. (AA). Here, 447,"Inflight break-up" may have been limited to the loss of R and VS as a unit. Because the part is missing does not guarantee the disintegration of the rest of the Airframe.

I too think that ACARS is post event. My inkling is that the game was up at a/p disconnect and "Alt.Law". a/p disc., Alt. Law, excessive Rudder.

Aside. A rudder is nice, it trims the a/c. Without it, things are not nice, but survivable. Without a VS, controlled flight is virtually impossible.

So why does the Rudder always seem to take the VS with it when it exceeds its structural limits? Had AA only lost its Rudder.....?
Will Fraser is offline  
Old 8th Jun 2009, 19:22
  #665 (permalink)  
 
Join Date: Jul 2005
Location: エリア88
Posts: 1,031
Likes: 0
Received 0 Likes on 0 Posts
Some picture visuals show clearly and with no doubts .. the fracture of the vertical stabilizer is not situated at the base (connection of the stabilizer to the fuselage)
Again, I completely disagree.

The remains of the attachment lugs are visible at the bottom of the fin, the different colour of the protective coatings is also clearly visible in this area(its a sandy yellow/brown colour) and as already mentioned, the white line where the blue and red logo stripes finish is also visible and is both perpendicular and of equal spacing.

There is damage to the rear of both the fin and of the rudder.

Also, it might help if people would refrain from photo shopping images from the crash site.
Mercenary Pilot is offline  
Old 8th Jun 2009, 19:27
  #666 (permalink)  
 
Join Date: Jun 2008
Location: Greenland
Posts: 28
Likes: 0
Received 0 Likes on 0 Posts
Pitot-failure

On ground low power is applied to the probes.
(at least one engine operating)
In flight it changes to high.
Probe caution light can be a spurious failure+
can sometimes be reset.
Companys like Goodrich,Thales or Gsis are manufacturing probes.
All of them can fail (heating elements).
Has nothing to to with FBW.
In recent years two 757 are crashed, due to airspeed
failure, caused by the same problem.
connector is offline  
Old 8th Jun 2009, 19:29
  #667 (permalink)  
 
Join Date: Jan 2008
Location: Berkeley
Posts: 67
Likes: 0
Received 0 Likes on 0 Posts
> Tim Vasquez knows enough to state with confidence that thermal
> bubbles with 20-30 K higher temp

"Bubble" refers to a thermal rising. That's not the concern around a cumulus that penetrates into the stratosphere.

Tim Vasquez has amended his web page since -- someone sent him a reference.
Google penetrative cumulus stratosphere temperature

The stratosphere is relatively much warmer air, and dry; that air mass gets displaced when a cumulus penetrates significantly up into the stratosphere.
It's bubbles going _down_ around the edge of the cloud that are the concern.

"It's what you do know that ain't true that will hurt you."
ankh is offline  
Old 8th Jun 2009, 19:43
  #668 (permalink)  
 
Join Date: Nov 2006
Location: SoCalif
Posts: 896
Likes: 0
Received 0 Likes on 0 Posts
"..In recent years two 757 are crashed, due to airspeed
failure, caused by the same problem.."

The AeroPeru 757 static ports had been taped over for skin polishing on the overnight, being undetected when plane unexpectedly put in service, due to a 727 aog. I don't remember if the pitot tubes had been sealed as well, but it is immaterial, as without accurate static, the airspeed indication is misleading. The pitot probes did not fail or ice over.

In a simpler plane, inaccurate airspeed indication is not a killer. Perhaps someone could list the systems adversely affected by inaccurate airspeed indication in the A330.

!. Mach/IAS Hold, of course
2. Rudder Travel Limiter
3. .

GB

Last edited by Graybeard; 8th Jun 2009 at 19:46. Reason: typo
Graybeard is offline  
Old 8th Jun 2009, 19:49
  #669 (permalink)  
 
Join Date: May 2007
Location: Dark side of the Moon
Posts: 545
Received 46 Likes on 24 Posts
Mercenary Pilot ,

A further confirmation that the picture shows the entire VS & rudder assembly is that the start of the change in angle of the leading edge of the VS is clearly visible in the original photo (not so obvious in the extracted picture).

FBW
Fly-by-Wife is offline  
Old 8th Jun 2009, 19:51
  #670 (permalink)  
 
Join Date: Jan 2008
Location: Atlanta, GA, USA
Posts: 349
Likes: 0
Received 0 Likes on 0 Posts
I'm at a loss to understand this obsession with the air speed indicated. The VS/rudder assembly has popped off completely intact with the rudder still functioning (you can see it deflected to starboard in the second linked photo), an even more dramatic event that AA 587. It seems to have been found off by itself (else other floating composite debris would be seen). It seems pretty clear that this is the same scenario as AA 587 - perhaps heavy rudder input during a rough patch. Once the tail and rudder were gone, the plane would starting yawing back and forth until controlled flight was lost, with obvious effect on the air speed sensing.

-drl
deSitter is offline  
Old 8th Jun 2009, 19:55
  #671 (permalink)  
 
Join Date: Jan 2008
Location: Germany
Posts: 11
Likes: 0
Received 0 Likes on 0 Posts
Unhappy

Look at the pictures from the A320 down in Perpignan.
The vertical stab was also detached upon impact and was found floating in one piece. It did not detach in the air obviously....
737only is offline  
Old 8th Jun 2009, 19:56
  #672 (permalink)  
 
Join Date: Jul 2002
Location: california
Posts: 35
Likes: 0
Received 0 Likes on 0 Posts
ACARS Message

1 - The date stamp of the LAV CONT message is from the evening before (2245)

From a pilot prospective and arguably by just looking at the failures on the list:

2- One ADR failure is NOT consistant with flags on PFDs. (airbus eliminates 1 erroneous data source if 2 others are the same, transparently to the pilots)
BUT
Two ADR failures is ! and the ECAM message would read:

3- NAV ADR DISAGREE ! which we find in the list.

4- which in turns get the Airbus to revert to ALT LAW without protections (overspeed, and alpha)

5- autopilots, ATHR, NAV TCAS and F/CTL RUDDER TRVL LIM are associated inop items.

6- F/CTL computers (Prim 1 and SEC 1) could then be reset, and recovered (or not) (they receive wrong data from ADRs)

We're left with the STBY probe, feeding directly (no ADR) the ISIS (self contained stby instrument). Which also seems to report faulty info !!

Near Max rec ceiling, the operational airspeed margin on a jet is quite narrow. easy to go to overspeed, or a stall (no protection), especially in very turbulent conditions.
Flight manually assured using good old techniques of "Pitch and Power", in the QRH for "unreliable airspeed"

7- last message on list : ADVISORY pertaining to Air cond/pressurisation MODE Fault, seems to be linked to cab descent rate (unable to cope with a high VS descent to maintain required DIFF pressure !)

Now we'll have to wait for FDR / CVR recovery ! if ever.
captainflame is offline  
Old 8th Jun 2009, 19:56
  #673 (permalink)  
 
Join Date: Jan 2008
Location: UK
Posts: 266
Likes: 0
Received 0 Likes on 0 Posts
The tail's likely to be with the main debris field - otherwise (despite its size) it's a very small pin in an extremely large haystack. Time will tell...
worrab is offline  
Old 8th Jun 2009, 19:58
  #674 (permalink)  
 
Join Date: May 2002
Location: Downeast
Age: 75
Posts: 18,248
Received 451 Likes on 179 Posts
I wonder if the US Navy SOSUS facility at Dam Neck, Virginia provided any information regarding the location of the crash site. They would surely have been able to pick up the sounds of the impact. If seismic sensors picked up the impact ther sonar hydrophone system operated by the Navy would have as well.

That information would be fairly accurate as to location as shown by the system locating the USS Thresher loss site and later the USS Scorpion.
SASless is offline  
Old 8th Jun 2009, 19:58
  #675 (permalink)  
 
Join Date: Apr 2009
Location: Petaluma
Posts: 330
Likes: 0
Received 0 Likes on 0 Posts
Graybeard

The question is not one of relative complexity of a/c. Pitot failure (even all three "combinations"), is serious, but what is the reaction of the a/c? If in automated flight, what is the prescribed sequence of corrections or accomodations? Does the a/c hesitate, then initiate another 'regime'? Or does it give up, "parameters exceeded" and quickly revert the a/c to hobbled control inputs after automatically disengaging equipment that the two pilots have quite understandably grown to grant their immediate trust? Three separate computers? Excellent!! Some trained for reversion sequence with immediate and automatic displays?? NO??

Why is the Rudder attached so firmly to the VS? A Rudder is a trimming device. Without a Rudder? Quite flyable. No VS?? You are going down.
Will Fraser is offline  
Old 8th Jun 2009, 19:59
  #676 (permalink)  
 
Join Date: Jan 2008
Location: southwest
Age: 78
Posts: 287
Likes: 0
Received 0 Likes on 0 Posts
deSitter

The rudder travel is limited at high speed to prevent the AAL situation. If the airspeed indication is no longer reliable, then there'll be no reliable rudder travel limitation.
Hence the ACARS message.
Dysag is offline  
Old 8th Jun 2009, 20:02
  #677 (permalink)  
 
Join Date: Aug 2002
Location: Switzerland, Singapore
Posts: 1,309
Received 0 Likes on 0 Posts
My last post has been deleted (again), so I have to post it, because I think it is an important information:

The vertical stabilizer broke this way because it is designed that way. It is hold by several titanium bolts on top of the rear fuselage. The fin itself is designed much stronger than the bolts. So either the fin remains on the fuselage or it breaks. If it breaks, it breaks exactly there.

The AA587 was an A300 btw, not an A330.

Dani


You mean your last post (#665) that is still there?

Duck
Moderator
Dani is offline  
Old 8th Jun 2009, 20:05
  #678 (permalink)  
 
Join Date: Jun 2008
Location: Greenland
Posts: 28
Likes: 0
Received 0 Likes on 0 Posts
pitot

GB

1996 Birgenair TC-GEN
connector is offline  
Old 8th Jun 2009, 20:13
  #679 (permalink)  
 
Join Date: Sep 2008
Location: MI
Posts: 570
Likes: 0
Received 0 Likes on 0 Posts
Flyinheavy -
But I am damn sure, that they had all legal requirements fulfilled.
I never questioned whether they had the "required" fuel or not, merely that they might not have had the Contingency Fuel that I and others might've had aboard that night considering the wx enroute.
DC-ATE is offline  
Old 8th Jun 2009, 20:14
  #680 (permalink)  
 
Join Date: Apr 2009
Location: Petaluma
Posts: 330
Likes: 0
Received 0 Likes on 0 Posts
I would like to challenge an engineering response at this point.

My suggestion is that the weak joint should be Rudder/VS, not VS/fuselage.
Will Fraser is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.