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AF 447 Search to resume (part2)

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AF 447 Search to resume (part2)

Old 22nd May 2011, 19:41
  #2121 (permalink)  
 
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This fish wrapping slease rag and the Speagle are spreading crap.

Report: Pilot "not in cockpit" when Air France plane ran into trouble - Monsters and Critics
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Old 22nd May 2011, 19:46
  #2122 (permalink)  
 
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Tail chutes are not fitted to production aircraft because of cost.

A BAC 111 was also lost during flight testing through a deep stall.

BA carried out a study with a water sprinkler system in the cabin after the airtours/manchester disaster - although it would save lives it wasn't fitted due cost.

Same as smoke hoods for pax.

money money money
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Old 22nd May 2011, 19:50
  #2123 (permalink)  
 
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AoA "input"

Considering that previous 'bus incidents had erroneous airspeed as a major contributor to the ends results, why would Airbus not consider AoA the primary consideration in an "upset"? I wonder....
What kind of implications for this? Software, training, philosophy?
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Old 22nd May 2011, 19:51
  #2124 (permalink)  
 
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Stall Recovery

The relevance to AF447 is toward the end:

1979 was a bad year for the DC-10, and it was almost worse.

May 25, KORD: Engine came off AA DC10-10; all fatal.

June-July: Entire DC10 fleet grounded due to overraction to pylon mount cracks.

Aug, XMEX: WAL, Western Airlines DC10-10 landed on closed runway and collided with truck: 50 fatal.

Nov, Antarctica ANZ DC10-30 KSSU config hits Mt. Erebus; ~260 fatal; Recovered data exonerated the plane.

What didn't hit the mass media was this incident:

Aug, climb out from Frankfurt; AeroMexico DC10-30 at gross cleared to 31K feet. A/P in 1500 fpm climb mode until 27K feet, where the engines couldn't maintain 1500 fpm, so pitch increased into a full stall. In spite of stick shaker, Capt failed to recognize the extreme vibration as the overhead panels were coming down in the cabin, etc. Capt declared Mayday, and then decided to pull power on #3 engine, believing that to be the cause.

Pulling power to #3 put the plane in a spiral, which the Capt recognized, and recovered at 10K feet. He canceled Mayday and continued on to KMIA, where they discovered damage to ailerons, and the elevator counterweight horns were missing.

Departure may have been Madrid, but either way, it might have ended in a deep sea search.

So, the question: will pulling power to one engine of a big twin in deep stall help?

GB
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Old 22nd May 2011, 19:55
  #2125 (permalink)  
 
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Software Engineering/Reliability, Peter Mellor

DozyWannabe,

Thanks for very interesting info.
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Old 22nd May 2011, 20:01
  #2126 (permalink)  
 
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A Near Loss

I recall hearing about this incident a long time ago. During the testing/certification of the A-320, one of the test aircraft was almost lost. The pilots were doing some sort of testing at an altitude between 30-33K. For some reason, they got into a pitch up, wings level situation and couldn't get the aircraft to roll or the pitch to come down. Finally, they retarded the throttle on one engine to idle and the other to max thrust. The aircraft then started to roll and the nose came down. They got control of the aircraft at approximately 10K, not much room left.
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Old 22nd May 2011, 20:10
  #2127 (permalink)  
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GB "...So, the question: will pulling power to one engine of a big twin in deep stall help?..."


Won't that depend on how the Thrust is "Pointed"? Rudder, Elevator? As I recall, the DC10 that lost (sic) number one on TO had ample airspeed to fly its commanded AoA (By F/O). When the Captain took over flying, He could have reduced thrust on #3, and mitigated the a/c's obsession with rolling (over) to the left. As it was, Thrust was left full, and the a/c had insufficient Yaw authority to prevent its rollover to the left. There is a rumor that Captain's foot slipped a split second on takeover (The Right Foot), allowing a smidge of left Yaw, sufficient to unrecover.

This was at 500AGL on a clear day, with TWO engines left. It would at least seem after all this time that the flight crew (447) were surprised, and possibly unable to pull things together, for reasons we'll soon know.

************************************************************ ***


Beyond a certain threshold, doesn't Thrust (even power to keep 'flying') simply make things worse?

Last edited by bearfoil; 22nd May 2011 at 21:10.
 
Old 22nd May 2011, 20:17
  #2128 (permalink)  
 
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Apology for the previous interjection to a good on going discussion, but news media give me the willikers.

In a stall with a tri engine configed craft, the tail engine oomph will work wonders.
We need 411a back.
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Old 22nd May 2011, 20:18
  #2129 (permalink)  
 
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Airbus FBW EMI-resistance testing (including lightning)

Quote from RR_NDB:
A test 787 (ZA001) was hit by a lightning bolt and survived. (landed). During the Test phase or Certification process, the airliners are "lightning tested"?

Response from DozyWanabee:
I don't think so, but the laws of probability suggest that many a FBW Airbus model has been struck by lightning in one form or another in their 23 years of airline service and not one has fallen from the sky because of it.

This is way outside my expertise, but those of us who were the first line pilots to fly the A320 had naturally taken some interest in the subject.

My recollection is that they had parked one on the military airfield at Istres (engines running) and bombarded it with radiation on a wide range of frequencies. The flight testing had also involved flying into deliberately-selected Cu-nims on a number of occasions. The story was that there had been one or two FCC trips, but that a normal reset had been achieved.

In 14 years on the A320, I was struck by lightning on about six occasions. The worst case was on the approach to Bilbao Rwy29. We lost both Radar transceivers, and after landing there was a hole in the radome you could have pushed your head through. However, at the time of the strike, we had no noticeable electrical transients, and no failures of EIS or FCCs.

Chris

PS
DozyWanabee's post indicates that the A320's 2 ELACs (Elevator-Aileron) use the Motorola 68000, and its 3 SECs use the Intel 80186 (this was the late 1980s and PCs were in their infancy). As DW says, ELACs and SECs each have a command channel and a monitor channel. I think the software engineers writing the command channels were segregated from the team doing the monitor channels. My (no-doubt simplistic) layman's understanding was that each team received the requirements from the flight-control designers in the form of logic diagrams, using "and" gates and "or" gates. Instructions in plain English/French/German were strictly avoided.
The other key part of the A320 flight-control architecture are the 2 FACs (Flight Augmentation), which, among other things, calculate V-speeds and manage all the rudder (yaw) functions.
In my 14 years, I never experienced an FCC failure.

Last edited by Chris Scott; 23rd May 2011 at 11:36. Reason: PS rewritten, after reading DW's post more carefully!
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Old 22nd May 2011, 21:00
  #2130 (permalink)  

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jcjeant,
e copy of the investigation report (who is also public) it's just a information document and can't be used by prosecutors for point any responsible or irresponsible people or corporation
Fair enough. What is the basis for the whole trial, then ?

The only reports used will be those show at the court by the experts named for this case.
And the experts are basing their findings on what ?

Only will be exhibit .. the judiciary experts reports ... even if it's a conform copy of the BEA report
Ah ! And how many times that hadn't happened ? Pray tell.
The investigation is so expensive and needs to be so thorough that the BEA report is in all cases the main exhibit, as the NTSBG is in the US and the AAIB in the UK.
At the trial, parties are quite allowed to show their own evidence, but we are, after all in France and the system here is that most of the discovery has been done by all parties with the help / assistance / supervision... of the court : the instruction judge generally.
Now, whether you like that system or not is irrelevant and far better peoiple than you have accepted the French way of judicial procedures and found it fair... See for instance the people at Bielefeld University.
Of course, with an agenda and some prejudice, everything is possible.
What should be possible , too, is that people could grow up.
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Old 22nd May 2011, 21:12
  #2131 (permalink)  
 
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PJ2:
In the meantime, the flight controls, even in ALT2, will all be trying to satisfy all movements of the stick (within the limits of ALT2) while trying to satisfy the commands of the flight control laws in keeping the aircraft at its last-commanded attitude.
Help me here (or not).

If the ALT 2 command is already full nose down in a stall, nose down sidestick does nothing additional and nose up sidestick just perpetuates the condition??

Once again sorry if covered before.
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Old 22nd May 2011, 21:23
  #2132 (permalink)  
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I am intrigued by French Law. I hope that soon there will be a thread in R&N about the trial.

Evidence at Trial in the US, (US Law is based on English, "Queen's Bench"), is submitted (entered) ultimately by the Court, regardless the proffer. 'Special' or 'Expert' testimony is likewise allowed if any challenge by counsel should fail. Subsequent testimony rests on the evidence, which stands on its own.

I can't quite get what the report from BEA has that affects its proffer, and any subsequent determinations. Of course it is admissable, yes? I cannot imagine what either side would have against it. At Court it will be massaged by both, and even though the Final Report is strictly forbidden from assigning Blame, rest assured counsel will have no such sanction.

OK465 Does the Nose Down command rely on Manual trim wheel ? I recall that to reject a/c command for nose up, the sidestick has to be pushed fully forward to trip it? Then manipulated in concert with a recovery ?

Last edited by bearfoil; 22nd May 2011 at 22:16.
 
Old 22nd May 2011, 21:55
  #2133 (permalink)  
 
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Speculative thoughts about a gyro-stabilized a/p reversionary mode.

This is beginning to look like the X-31 scenario. Once actual airspeed is far enough from system accepted airspeed, the control system gains become set inappropriately and the control system becomes unstable.

The Captain might have had a clue from deck angle when the carts started to roll, or he may just have heard the "Cavalry Charge" through the cockpit door
I find it interesting that (if I understand things correctly) if two of three air data units malfunction, the autopilot disconnects and demands that the plane be hand-flown, just when the essential airspeed data is unreliable.
What if the autopilot in that case would revert to use inertial (gyro) data as autopilot input?
(As the quote above illustrates, a dangerous pitch-up could be eminently noticeable by anyone in the plane - except the pilots, who potentially may be so fully concentrated on deciphering the ECAM messages that they fail to notice the g or pitch increase.)

It would not be rocket science to design an inertial data driven reversionary a/p mode, which might even be automatically activated in case of an unreliable airspeed indication. Just to keep the plane on a steady pitch angle while the crew sorts out the problem.

Those modern inertial data units or "gyros" measure both turn rates and linear accelerations with high precision along all three axes, so it seems at least theoretically possible to have such a unit drive a stable 1-g flight path also without airspeed data.

I realize turbulence may lead to potentially dangerous airspeed over/underspeed excursions, as a pure inertial system would try to keep the speed over ground stable. The most obvious remedy to that which I can think of would be to descend to a slightly lower altitude using e.g. GPS as altitude source, to get more speed margin. If necessary e.g. due to weather ahead, do a 180 turn.

It seems that most (all?) serious unreliable-air-data incidents have to do with iced-up pitot tubes, which however is usually a temporary condition. This reversionary mode could help keep the plane in control until the ice melts and air data comes back.

Any thoughts? Or is this capability already existing?
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Old 22nd May 2011, 22:14
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Lightning bolts to "electronic" a/cīs

Hi,

bombarded it with radiation on a wide range of frequencies. The flight testing had also involved flying into deliberately-selected Cu-nims on a number of occasions.
The lightning generates a broad spectrum of RF. We can "hear" it in the NDB and in the VHF, etc. The EMI/EMC issue is important and we can easily imagine the intrinsic susceptibility of circuitry to "interference". The Istres testing was for this. Also observing, FADEC. This was for radio "interference".
The ACARS (now two, after mm43 post) perhaps indicating a buss fault warned me to remember a training i had in PHX area on this subject. Don White also told about Tempest, a classified content. The EMP (electromagnetic pulse) of the lightning has a steep rise of energy in time. Worse is the nuclear blast. Itīs EMP could destroy the "front end" of a HF receiver (connected to an antenna) hundreds of miles from the blast.
But the lightning also carries "high current". We can "see" it in the flash.
My comment was about the current in the nose of a highly electronic a/c is like when we was in a C47 hit by a cloud-cloud bolt (i remember the ozone odour and the noise) at FL 080. The theory is that the "static current" flows outside the fuselage. But the holes we did see in the skin (thin for high currents) may suggest some energy "enters". And there is some "induction inside" the fuselage. (the fuselage like a coaxial cable receiving current in itīs shielding). I respect a lot this issue. High energy involved. I did see a gas station pump, knocked out by a bolt. And the road ahead a car of a friend "melted" before raining, etc. How many times displays "flickers" when crossing electrically charged space? Anyway the design (shielding, spatial redundancy, etc) and the statistics like commented earlier are an important argument that the issue is "under control".
The story was that there had been one or two FCC trips
Theoretically this would not occur. So...Better to stay away the phenomena when possible. After the "testing" the 787 was "reinforced" in this aspect. I heard of IIRC a F28 that lost hydraulics after a bolt. (with currents flowing in the "wrong circuit") And big planes crashed as a result from ignited vapors in fuel tanks. (L188, 707 and a 747)

The "testability" of this kind of susceptibility is a problem. No "man made generators" available. New designs, "composite intensive", requires attention.

Last edited by RR_NDB; 23rd May 2011 at 05:47. Reason: add info
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Old 22nd May 2011, 22:40
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No "man made generators" available.
Sure they are. Every high tension test site has them, since high voltage surge protectors need to be tested too. The general lightning bolt shape with rise and fall times and current range 10kA to 100kA is well understood. There is a physical mechanism in place which limits the rise times and the bandwidth of a lightning bolt. So testing is not that difficult but might be a bit destructive on the airframe.
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Old 22nd May 2011, 23:17
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Positive Lightning

That would not be sufficent to test the effects of positive lightning on an aircraft , it is up to ten times more powerful than negative lightning (95% of lightning is negative lightning)
NWS JetStream - The Positive and Negative Side of Lightning
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Old 22nd May 2011, 23:56
  #2137 (permalink)  
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They got control of the aircraft at approximately 10K, not much room left.

Occasionally it is apparent that death is looking the aircraft's crew in the face .. at which stage to try anything with a chance is better than putting one's head between one's legs ...

This is the characteristic of the traditional pilot .. not to give up and wave arms around in frustration... even when it is obvious that the die is cast with no chance of rectification ...
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Old 22nd May 2011, 23:57
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stick technique

Chris Scott's notes on sidestick technique are worth a read even for non-FBW pilots.
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Old 23rd May 2011, 00:00
  #2139 (permalink)  
 
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Well I don't know about +ve/-ve lightning [actually I do ], but in an Airbus context, I clearly remembering watching test/development aircraft MSN2 fly directly into an intense squall line shortly after take off and receive 5 visible strikes before it was enveloped in the cloud....... 43°39'1.63"N 1°20'6.37"E....

which I guess was the point!

'twas a cold, humid evening coming from a warm afternoon...
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Old 23rd May 2011, 01:06
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OK465 Does the Nose Down command rely on Manual trim wheel ? I recall that to reject a/c command for nose up, the sidestick has to be pushed fully forward to trip it? Then manipulated in concert with a recovery ?
bearfoil:

Automatic pitch trim is available in alternate law.

Are there are exceptions to this in alternate law? Somewhat ambiguous in syntax as the word 'always' is not used. If there are times when it is available and times when it is not, you could use this phrase. If it is always available you could also use this phrase. (Could it be available and not active?)

Assuming it is always 'always available' you bring up a good question.

When the low speed stability function is progressively commanding nose-down elevator, what flight condition is the THS being automatically trimmed for?

I'm pretty sure in ALT 2 with dual ADR failure in a stall when the pilot manually rotates the pitch trim wheel it will remain where the pilot leaves it. (Would you get a USE MAN PITCH TRIM on the PFD like in Direct Law?)

But I'm willing to entertain the "you don't have a clue" inputs from more knowledgeable Airbus experts. I have a thick skin and learn from my mistakes.
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