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AF447

Old 8th Jul 2009, 15:18
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FanAviation

It is tempting to send this as a mere PM, but I think it may be helpful for a few of us. My conclusions re: the report, have to do with its whole appearance, context, continuity and related elements of purpose. Fanaviation, I see your point clearly, and in a way I would defend the paper as you are. However, and this is very complicated to convey, there are some very subtle constructs at work here, and without your understanding of the paper's purpose in all its iterations, your view of the actual product will be directed by perhaps said lack of understanding.
The mechanism at issue here transcends language, believe me. I apologize if I myself misunderstand your apparent defense of the Report.

Will

fyrefli

I agree with you. "attitude of flight" can be interchangeable with 'en ligne de vol'. As "heading" there is also evidence in the debris to support a claim of Horizontal travel at impact. That evidence was not addressed, and "forward flight" was left to be mysterious, as was any "rotation" of a/c at impact, which is also demonstrable in evidence, but was not so demonstrated. This report has the appearance of hit and miss reporting, some conclusions are offered, some hinted at, some treated differently, and therefore ignored. The jumbled nature of the paper is not evidence of the BEA's inability to write a conclusive and coherent preliminary statement, nor of the lack of time in which to prepare one.

Will

Last edited by Will Fraser; 8th Jul 2009 at 15:31.
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Old 8th Jul 2009, 15:22
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Will, I for one understand what you're getting at - again, perhaps I could have mentioned that in my previous post on the translation but, as a purely recreational pilot, didn't want to overstep the mods' boundaries.
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Old 8th Jul 2009, 15:28
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syseng68k

If you read back a few hundred posts or so, there was already fairly clear evidence and discussion about the direction and forces required to break it off...

I am now (trying) to go one stage further, the subtlety of bringing it back into discussion after BEAs preliminary comments though, seems to keep getting lost....
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Old 8th Jul 2009, 15:35
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Will, I for one understand what you're getting at
I think many of us do.... even though a large proportion don't fully subscribe or realise to do otherwise -at this stage - would be unwise.

Th facts were fairly simply and fully stated and one or two initial ideas on the crash impact itself based on their structural analysis of debris put forward.
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Old 8th Jul 2009, 15:38
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ARFOR;
- If one engine (either one) failed, at what shaft (% RPM) would the associated GEN trip out?
A quick review of the AOM does not provide an RPM. However, if I understand your point, you may be thinking that a windmilling engine may supply electrical power and that would not be the case as a windmilling high-pressure compressor section rotation at cruise speed is below the RPM required for electrical generation (The RR Trent would be around 12 to 15% if I recall correctly from the sim but someone with current experience may be able to confirm/correct this. I believe the gearcase is taken off the N3 but, frustratingly, the AOM doesn't tell us - the AOM NTK - need-to-know, description is about the level of, "the engine has 3 rotating sections with turbines attached...).
- Notwithstanding the above, following a single engine (either one) failure, would AC1 remain energized by the other power plant? If yes;
- Following the inevitable ECAM/s, would ACARS output message/s?
Under normal (design) circumstances, all AC and DC busses remain powered; there is some load shedding, (galleys) in loss of generation.

As you say, the ECAM would display the failures and the required actions. FLR/WRN category messages would be generated and recorded by the FIDS, (Fault Isolation and Detection System), collated by the CMS (Central Maintenance System) and sent to the ACARS for maintenance action. In short, they would be a part of any transmitted messages.
- Following an asymmetric failure (whilst in ALTN 2), how promptly would the PF need to get rudder in to avoid yaw induced roll?
It is entirely dependant upon yaw developed in the spectrum from idle thrust to takeoff/go-around power. An engine failure at idle thrust would not require any rudder at all; an engine at takeoff thrust requires an immediate response, and initially requires about 14deg of rudder, from which one backs off (after trimming out the yaw), depending upon the airplane's needs. In cruise, an engine failure would require an immediate but small application of rudder, (gently!). As with all high-altitude flight one must be careful with the use of controls because thin air provides so little damping effect. Providing rudder is used judiciously, roll-due-to-yaw is not a problem.
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Old 8th Jul 2009, 15:44
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At 30 deg. C, the average specific gravity of saltwater is 1.022g/cc^3. That of the average human body is very close to 1.00., so, in those conditions, a body would be barely on the surface, at least until enough methane, hydrogen sulphide and trace mercaptins were generated to raise more of the body out of the water.

Last edited by 4nsicdoc; 8th Jul 2009 at 15:45. Reason: spelling
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Old 8th Jul 2009, 15:48
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HarryMann

I believe the spoiler is very important for what it can suggest. With Flaps 0, there is no airflow available to pop the spoiler out of its mounts. With any deployment, the area under the spoiler opens up and exposes the underside of the spoiler to some value of airflow. As with the Engines discussion (long in coming, I think), there is reason to entertain some configuration that at first blush might seem ridiculous, but perhaps not to pilots up against upset, uncontrollable a/c, and impact with the Ocean.

Will
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Old 8th Jul 2009, 15:59
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Translation

I understand how a lot of the threaders here, not being fluent in french (or have NIL notion of it at all) have difficulties understanding the BEA statement regarding the "probable" way the aircraft impacted the water.

Can you please trust the french speaking airmen here present, who KNOW both languages, especially the aeronautical terms, to translate what this means without having to submit other ludicrous attempts at google translating and other wikipedia electronic translations and so on, to get a CLUE !!

As stated previously, "en ligne de vol" means "flight attitude", which does mean attitude of the aircraft.
They mean it impacted flat, that's all.

Please don't ANY not french speaking person tell me this is not correct !!
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Old 8th Jul 2009, 16:02
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Will;

For information only and not in response to notions posited, it is possible that hydraulic power would be available from a windmilling engine depending upon forward speed. 250kts Indicated would do it, 180kts maybe. However, high-demand services such as flaps would likely not operate or would be extremely slow. Also, the RAT (hydraulic power only - very low flow) requires 260kts for full (8.7KVA) emerg gen operation, otherwise loads are shed as output is reduced to 3.5KVA.
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Old 8th Jul 2009, 16:08
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captainflame

I understand your frustration and annoyance. By way of explanation, there is a difference between a definition of a term in any language, and what is meant by its use. Do you see this? This is not about what words mean, but what people mean in using them.

Your conclusion that "this is what they meant" is open to serious question. If that is not understood, then we will just have to agree to disagree.

Will

PJ2, noted, and thanks, as always
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Old 8th Jul 2009, 16:34
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can I ask

Is the reverse view of the orange container here the back of the galley structure previously discussed?

More New Photos of AF447 Wreckage at Flightstory.net - Aviation Blog

If so, the impact looks to have been remarkably vertical and of (relatively) low intensity. That structure would be very weak in shear.
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Old 8th Jul 2009, 16:38
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high density of ice crystals & columnar ascents in Cb

Hi there,
The following article may be of interest: SKYbrary - High Level Ice Crystal Icing
This one can give clues about ice crystals observed (or not) by conventional E.M. weather onboard radars like the ones on airliners and by several Lidars
AMS Online Journals - Studying Altocumulus with Ice Virga Using Ground-Based Active and Passive Remote Sensors
Seems that these dry crystals are difficult to detect using E.M. radars.
Jeff
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Old 8th Jul 2009, 16:43
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If you read back a few hundred posts or so, there was already fairly clear evidence and discussion about the direction and forces required to break it off...

I am now (trying) to go one stage further, the subtlety of bringing it back into discussion after BEAs preliminary comments though, seems to keep getting lost....
I think I see what you are driving at: As with the vs, there does seem to be disagreement between the report and direction of travel required to sever the vs and / or spoiler, unless the impact vectors included speed opposite to direction of flight. Correct me if i'm misreading this, or you have a better explanation.

As an aside, some info and pics on spoiler manufacture which may be of interest:

Composite Spoilers Brake Airbus For Landing: COMPOSITESWORLD.COM
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Old 8th Jul 2009, 16:45
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...Seems that these dry crystals are difficult to detect using E.M. radars.
Jeff
Yep, that's why the procedure to paint at the freezing level of the storm before getting close. That's covered in techlog.

GB
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Old 8th Jul 2009, 16:48
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Will,

Excatly right, it's what they mean.

I submit to you that a French speaking airman is able to tell anyone what the BEA means with this statement.

Whether you put it in doubt or not is another story !
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Old 8th Jul 2009, 16:52
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Those pics have been seen, I think. The triangular web "mounts" on the "lid" of the cabin structure indicate a horizontal moment at impact. The direction of failure (roll) of the mounts would indicate a horizontal vector the direction of which could be determined by the structure's installed orientation.

The control surface at the bottom (of the third photo) is the one that engendered the "aileron" vs. "elevator" discussion, I believe. I still think it to be part of the HS, perhaps the "trimmable" Horizontal Stabilizer as mentioned in the Prelim. What ever the case, make note of its conditon; it resembles the damage evidenced in the spoiler. If the vertical accel. was low enough to permit the relatively whole appearance of the Galley structure and was the result of a horizontally expressed aspect, I would emphasize the poor appearance of the HS "part" (or aileron). A low speed pancake would suggest larger more intact pieces of the airframe. I think what the control surface damage suggests is high speed flutter.

Finding parts from "all locations of the a/c" (my paraphrase) reasonably co-located but showing variable damage would argue against "intact at impact." A very robust external piece is virtually destroyed, but an internal structure is reasonably intact indicates to me a prior disintegration of some kind. Finding parts in a small area (if that is the case) merely means the ballistics of all parts of the a/c were aligned vertically after a possible breakup and descent to the Sea's surface.

Will

captainflame I think I understand what you may mean by that.

Last edited by Will Fraser; 8th Jul 2009 at 17:13.
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Old 8th Jul 2009, 16:57
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wf

thanks. Considering the damage evident in an auto crash at 60 mph I find the 'lack' of damage (crushing and buckling of panels, intact joints, lack of 'swipes' by adjacent structures) intriguing.
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Old 8th Jul 2009, 17:05
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You are confusing side-effects with the essential requirements of spin entry and spins. And since like Dani, you wish to protect and retain your pre-existing mis-understandings I won't require you to change. Since this thread is about AF447 it would be inappropriate to sidetrack and give you flight instruction. I'll let my statement on spin entry stand, it is entirely accurate. Ignore if you wish. Hope that helped.
So you're saying spin entry is stall and roll-off. Not my understanding nor experience. Thought you were supporting the concept of stall and sideslip producing a spin. You can have stall and roll off without a spin. The roll off stops when the lift is dumped naturally. If you have stall and sideslip you get a spin if not corrected. Understand it appears the roll off is producing the spin to most. NASA has some elementary diagrams explaining the force balance during spins. We're on different levels. Good luck.
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Old 8th Jul 2009, 17:29
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Along the lines of my previous post above, I would include other parts and note the relatively large discrepancy in energy absorption performance. Again the Galley, being large and relatively light, suggests it was uprooted rather "gently". Now look at pieces of the cabin liner that include penetrations (manufactured) for ports. Small, torn violently (I would say) into small irregular shapes. I doubt this liner is CFRP, it is expensive, and high impact plastic would perform as well in any conceivable line duty. This material is very strong in shear, though thin and light. Any forces that produced a large enough force to tear it into small pieces would be expected to shatter the Galley into small bits as well. The force at work for liner failure, including the highly energetic destruction and delamination of the Crew's Rest capsule, would seem to be a separate event from entry into the water at a velocity low enough to allow for a gentle uprooting of the Galley. (Noting that this would be in disagreement with the Preliminary Report).

captainflame
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Old 8th Jul 2009, 18:08
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should you take stall alarms in account ?

The Eurocockpit website (Eurocockpit - Accueil) published today some interesting facts about the "unreliable airspeed" procedures, when the flight safety is impacted, as they are applied by the operators (at the date of the accident) and as they appear in the latest version of the Airbus QRH (at the date of the accident): the instruction to take in account the stall alarms in the operator procedure is no longuer visible in the Airbus QRH.
Jeff
PS) the differences between the two procedures can be seen page 67 of the english version of the BEA report.

Last edited by Hyperveloce; 8th Jul 2009 at 18:32.
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