Pitot tube simulator
 

By chance I found a Pitot Tube simulator on the internet. Using this you can block the drain port, etc, and study the effect. I don't know how accurate the simulation is, but the pitot tube is rather well described by bernoulli's eqn.
Try it. Here is a link:
luizmonteiro - Online Simulators - Pitot Static System Simulator
Perhaps it will make all agree to on what can happen.

Apologies if this question has been asked before but does the technology not exist to transmit whatever goes to the two black boxes back to a server at head office as well?

I would imagine it is possible with today's technological advances and whilst black boxes could be retained as a back-up they would, in most instances, not be needed.

Hi Doors to Automatic,

It has been discussed heavily on this thread. You will find postings on the subject when using the Search utility at the top of this page.

It will include information about available technology as well as limitations due to bandwidth and much more

Good luck!

:ok:

Should be worth watching. And you don't have to be in UK to get BBC2!

mm43

The Spoiler shown in your picture shows a typical air failure. The Spoiler, when deployed, especially in full, is a powerful lever. The force of the airstream is greatest at the trailing edge. When overloaded, the Spoiler uproots its hinges and "rolls" over its actuator, displaying its underside to the slipstream, hence the apparent upward failure.

BEA has also found that the flaps were stowed, protecting the underside of the spoiler from upward removal.

What interests me are the holes in the airside of the device. Clearly, the surface has been holed in at least three places. Nothing resembling a water flop would produce those high speed holes. My guess is that the spoiler was deployed to lose speed, but something parted the airframe ahead of it and blew those holes in it.

I would further state (guess) that the culprit may have been the Radome, having parted the nose in overspeed. If the Spoiler on the ship is the same one in the Sea, the evidence may remain, there appear to be no 'exit wounds' on the underside. If we're lucky, matching the projectile to the hole might roughly predict the two different airspeeds, instant.

bear

- how is this CAS derived?

It doesn't simulate above 20,000ft or 220knots as far as I can tell.

At alts/speeds in its range it doesn't seem to model the small over-read due to the drain blockage, but this is likely to be specific to the particular design of probe. The model includes drain because if both ram plus drain blocked the total pressure is locked in and indicated speed just becomes function of altitude.

The AA probe was originally introduced to fix unreliable measurements, the critical period of flight is during climb after take-off, blocked drain+ram = false indicated speed increasing with increasing altitude, during which period pitot tube heater failure has been fatal. This model can be used to see how this can happen.

I believe there is a possibility of 3 identical probes in same airstream could suffer common mode fault of slowly blocking drains at same time. With auto-thrust the indicated air speed would not be seen to rise if all drains blocked - just true air-speed would fall (by small unquantified amount). Calculated wind speed would rise and engine thrust would be reduced. Would 30-50 knots be an issue?

At 02:10 there was an ACARS report

PROBE-PITOT 1X2 / 2X3 / 1X3

Which requires, for example one working correctly, one blocked ram+drain (stuck), one blocked ram (drain open =read zero).

So any false speed readings were just before this point, and have only an impact on the state of the a/c when the auto control gave up.

bearfoil

Yep, put the trailing edge front on to high speed air flow. Barn doors are not designed to withstand airflow from behind [swept wing roll without VS, flick, yaw, all over red rover]. The only way that could happen is loss of the VS following assem upset at alt. :uhoh:

What precipitated the loss of the lateral control [the VS] is any ones guess [Takata will chime in i'll guess].

bear
not sure about your ideas with the spoiler panel, i think if the spoiler was overloaded the actuator would have burst through the panel rather than acted as a pivot for the panel to rotate over itself.


gs

goodspark

The actuator takes all the spoiler's load, and is engineered accordingly. Note how the corners of the spoiler are broken downward, and the spoiler itself has folded in on itself longitudinally, ('around' the actuator, which is missing). This collapse is patent in overload, it is likely the actuator was 'pulled' out of its bed in the spoiler, as the spoiler left the a/c. Note the missing structure, roughly the shape of the join: actuator/spoiler.

The "Feathering" of the composite is typical of a spread-load failure, as opposed to focal collapse. This spread load can be related to either Air or SeaWater. the reason I choose Air Stream failure is that I would expect Water to have completely destroyed this panel at entry speeds entertained by BEA (ie above 100 knots.)

Composite, as opposed to Aluminum, has an instantaneous load/memory. It doesn't last long, but long enough such that the stress, if built up 'slowly' will instantaneously communicate with the whole panel at the failure point, causing a generalized rupture, instead of 'tearing', in the case of metallic sheets, or even laminates.

bear

Spoiler functions
 

Quote from mm43 (post #1250):
"My understanding is that the outer spoilers can only be deployed following both MLG on the deck when landing or in a RTO above 72KT. Both outer spoilers are not used for speed brake or roll."

It's tough to keep up with the fascinating mm43/bearfoil dialogue (!) but, just for the record, Spoilers 1 are the inboards, and are the pair that are used only as Ground Spoilers (lift-dumpers). Spoilers 6 (the extreme outers) are used for roll. Perhaps someone with the Tech Manual can confirm that they (6) are also used as Speed Brakes?

Chris

PS (Edited addition)
The phrase now coloured pale orange has since been shown to be incorrect. See CONF_iture post #1273.

FCOM :

• The speedbrakes involve spoilers 1 to 6.
• Spoilers 1 to 6 act as ground spoilers.
• Roll control is achieved by 2 ailerons and spoilers 2 to 6 on each wing.

Bearfoil; CONF iture;

I confused my "inners" and "outers", and thanks CONF iture for alerting me to an error in the Andy Tracy doc. Will let him know.

For the record, the spoiler arrangement and numbering are as follows:-

http://i47.tinypic.com/34reiy8.jpg

There still seems to be universal disagreement as to the cause of the spoiler detachment, though I am personally in favour of the BEA's version, as visible breakage of the spar attachments point to a high unidirectional force, which I don't see being as a result of an overspeed event. The usual proviso - I may well be wrong. http://images.ibsrv.net/ibsrv/res/sr...lies/sowee.gif

Bearfoil; Apologies, my original supposition regarding the non deployment of the "outer" spoiler was wrong. However, the top surface of the spoiler could have been impacted with shrapnel from anywhere at time of impact.

mm43

Quote from CONF_iture:
"FCOM :
· The speedbrakes involve spoilers 1 to 6.
· Spoilers 1 to 6 act as ground spoilers.
· Roll control is achieved by 2 ailerons and spoilers 2 to 6 on each wing."
[unquote]

Salut Confit,

I see that the FCOM says Spoilers 1 act as Speedbrakes as well as Ground Spoilers. Am surprised for two reasons:
(1) The schematic posted above by mm43 appears to exclude them;
(2) They are much bigger surfaces than the others, as per A320 (which only uses them as Ground Spoilers).
Not sure if this effects the damage argument, but can you confirm from your own knowledge that the FCOM text quoted is not a misprint?

Chris

Chris,
I was a bit surprised too, but the text is supported by the following schematic :

http://i65.servimg.com/u/f65/11/75/17/84/af447_10.gif

According to the FCOM, in their speedbrake function, the maximum deflection for spoilers 1 is limited to 25 degrees, and that limit is 30 degrees for spoilers 2 to 6.

Chris Scott; Conf iture;

Strange that there appears to be a discrepancy, but a diagram I have indicates that the No.1 spoilers are for ground use only.

http://i45.tinypic.com/seuecl.jpg

I'm not sure of the actual source, but will try and find it.

EDIT :: Here it is:-

Electrical Flight Controls, From Airbus A320/330/340 to Future Military Transport Aircraft:
A Family of Fault-Tolerant Systems

by

Dominique Briere
Aerospatiale
Christian Favre
Aerospatiale
Pascal Traverse
Aerospatiale

The Avionics Handbook

mm43

What pray, is a high speed hole?
Or even a high-speed hole...

Please forgive me, if I cannot force myself to be more credulous :rolleyes:

mm43,
Unless you see something I don't, but to me both diagrams are pretty similar :
Spoilers 1 are controlled by the PRIM3 computer and powered by the Green hydraulic system. They are used as GROUND LIFT DUMPER as well as SPEEDBRAKES.

mm43

The diagram includes all twelve spoilers for both Ground and Speedbrake does it not?

Is your original schematic for Direct Law? (Roll Only) ?

CONF iture;
You are right, they are the same. Spoilers 1 - 6 are both ground and speed brake, roll spoilers are 2 - 6, and more clearly marked in the second schematic. I would say the Aerospatiale guys used the Airbus schematic as the basis for the one they produced.

Bearfoil;
Wasn't intended to be. But regarding the spoilers, it would appear that if 3 ADR fail, or VS1g computations fail, then there is no overspeed protection in Alternate Law, and side-stick input to spoilers in roll situation is direct and bank protections are lost.

EDIT :: As the flaps were stowed on impact, it is possible that they lifted cleanly upwards and took the spoilers out with them.

Oh yeah! I've put a red "strike-through" line through the reference to No1 spoilers not being used in the speed brake function in the A340 - A330 Control: Flight Laws

mm43