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AF447

Old 11th Aug 2009, 06:23
  #4201 (permalink)  
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Cheers, mm43 - interesting work as was takata's. Along with others, I too, think they'll find the wreck and the recorders.
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Old 11th Aug 2009, 06:37
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When is the incident archived

Out of curiosity

CVR and Data Recorders not found, bulk of wreckage not found. At what stage/time frame will the investigation committee "give up"?

In such instances what do they list in the investigation report? Has this happened before in any incident?

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Old 11th Aug 2009, 12:07
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Not directly relevant but as far as rapid descents and dives are survivable and the likely results of such... here is a copy of a post elsewhere on this board...
Saha Air 707 loses 2 on climbout



N712PA a JT3 engined 707 from Pan Am's initial 6 lost the No 4 engine over France on 25th February 1959 in a training incident, it landed at Heathrow and was repaired in the Pan Am hangar.

N712PA had been involved in a near 30,000 ft dive over the Atlantic three weeks earlier where it got close to Mach 1 ...possible autopilot malfunction ..... No 3 does'nt look to clever either!! ..... nobody checked the engine mounts?.

Mods read/allow/delete as required
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Old 11th Aug 2009, 12:50
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Debris distribution, currents & Final trajectory

Hey there !
Thank you very much mm43 for this nice work.
I visualize the final trajectory in a very similar way than yours, two aspects expected maybe:
- this large route deviation would be unvoluntary, this would be the horizontal trace (
large roll perturbation) of the high altitude cruise loss of control, this would occur as a consequence of a large exceedance of the MMO (Mach>0.89-0.90) and this severe overspeed would require ~1mn or over to occur [*]: the tight turn would start around ~02:11:00Z
- this turn would not be a constant load factor turn (a part of a circle) with such a high constant curvature radius but a trajectory where the shortest radius (highest load factor, highest roll) is at the beginning of the initial route departure and where it decreases (roll is being controlled) in less than one minute.
This tight turn would probably go with a rapid loss of lift/altitude ?
Once the roll is back under control, the pilots were in position to try to regain control in the vertical plane ? (AoA/incidence, pich). This would be the final part of the trajectory: rather linear in the horizontal plane and in the vertical plane, a rapid loss of altitude (~10 000 fpm), the AoA/incidence decreasing in a first time to regain the aerodynamical authority (also with the loss of altitude and the increasing air density - stall recovery) and increasing again to generate enought vertical Gs to try to break the catastrophic descent. The plane being "en ligne de vol" (straight horizontal trajectory / wings leveled, small horizontal speed component / speed mostly vertical, possibly a slight nose up)



Indeed the drifting of the bodies or of the debris can be very different if you look where was recovered the left wing spoiler (this latter, recovered north of TASIL, seems like an outlier in the debris distribution, it has not been much deviated westward by the westernly surface winds derived from the satellite scatterometers, see windscat). I will have another look to the surface current values over the first days of June since I have used values slightly lower than yours (and much lower than the SHOM values).

I am studying the slopes distribution of the seabed in the area where the debris should have been colocated the 1st of June at 02:15Z. I wish to validate my computations before I produce any graph results (missing values in the numerical terrain model) but it appear that between 5% and 10% of the seabed slopes are between 25 and 50, using a 1.25km square bin resolution (narroy faults, slope details finer than this 1.25 km are lost/not observable). This bathymetry must be a real pain: towing up and down the multibeam sounder with the relief, varying scanning speed/resolution as a function of the slope, etc... Would it be a luxury to send another high resolution sounder to probe this area ?
Jeff




Last edited by Hyperveloce; 11th Aug 2009 at 14:56.
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Old 11th Aug 2009, 13:08
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Airliners experimenting large overspeeds

Hey Harrymann. This seems highly relevant to me, I have also been searching such cases to validate my little speed computations (as a function of the thrust, angle of dscent, altitude, etc...). On the DC-8 cases (reaching Mach 1.012 around FL410 starting over FL500 and Mach 0.82), it would require 3 mn of a 5 controlled dive but I haven't found this historical details:
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Old 11th Aug 2009, 14:27
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Do y'all remember a post by me several pages ago about how (aerodynamically) clean most airliners are?

That when heavy (and even when not), they will accellerate happily to MMO and beyond with a 'mild' pitch excursion (or an expedited descent, perhaps along with a temp change/wind shear/shift)?

Look at the data from the DC-8 'dive'..... 5 degrees of nose down pitch.....

This in a 1960's DC-8 at high altitude.


So now, put yourself near performance cruise ceiling, at night, at cruise, and get distracted by..... anything. Forget WX, AltLaw, DirLaw, all the rest.

Find yourself hand flying a perfectly normal airplane. That's not a stretch.

5 degrees nose down is not far away. How long did it take to get to the surface? More than 5 degrees nose down.... That's not a stretch.

I'm just saying, I know how easily it gets fast.

Now put back in what we do know. AltLaw, DirLaw. WX. Possibly missing/faulty info displayed.

Not pretty.

Last edited by singpilot; 11th Aug 2009 at 14:38.
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Old 11th Aug 2009, 15:25
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This in a 1960's DC-8 at high altitude.
Yes, but surprisingly those wings were thinner, less super-critical, more sweep and could well have had higher Mcrit, surprisingly - just less optimised for the 'exact' cruise condition and fuel volume/sweep trade-offs..

I doubt you'd get an A330 above M 1.0 (in one piece)

Also, the lower by-pass, or even pure jets of that day, had much less momentum drag and indeed, the naceles also likely again, a higher Mcrit

Ditto fuselage diameter

But I'm not arguing your general case-making and assertions...

Last edited by HarryMann; 11th Aug 2009 at 15:58.
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Old 11th Aug 2009, 16:24
  #4208 (permalink)  
 
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Severe excursions of airliners beyond their MMO

Several airliners have exceeded their MMO, the China Airliner sustained more than +5 vertical Gs, even Airbuses, but with light excursions beyond their MMO (Mach 0.86-0.87). These ones recovered after a few thousands feet altitude loss.
I have read in an Airbus flight testing manual that the high speed stability could be tested, by inducing a voluntary/controlled overspeeding phase, waiting for the protection law to activate. It was indicated in any cases "DO NOT EXCEED MACH 0.90". I don't know about any Airbuses or Boeings having closed or exceeded Mach 0.90 in a single piece and survived. One Boeing has probably largely exceeded this limit largely during a high dive at medium altitude (and has gone supersonic ?) but it broke into pieces before the surface impact. It the middle of a mesocluster of tropical thunderstorms, nearing the highest top Cb cell tower, I really wonder whether you need to operate a large excursion beyond the MMO to loose your flight stability margins and really be vulnerable to turbulence. I also wonder about the detrimental impact of the spoilers during a significant excursion beyond the MMO (there was a problem in the overspeed procedures of the Learjet about this aspect, the one of the manufacturer and the one of the pilot being different, but I also know that the wing/airframe geometry of a Learjet and of an Airbus are not the same)
Jeff

Last edited by Hyperveloce; 11th Aug 2009 at 16:41.
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Old 11th Aug 2009, 16:36
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The B747 has been taken up to M0.99 True by Boeing and 0.98 during UK certification, and the handling remained good throughout. I don't know about the Airbus types.
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Old 11th Aug 2009, 17:52
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KLM/Air France have grounded their A330s.

Worldwide-Aviation.net
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Old 11th Aug 2009, 18:10
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When the French investigators concluded that 447 hit the water intact based on compression evidence from recovered wreckage, does this include or exclude the stabilizer?

Apparently, the tail was recovered >50 miles from much of the rest of the recovered wreckage and the automated electronic messages transmitted to AF indicate a decompression event ocurred earlier?
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Old 11th Aug 2009, 18:20
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The BEA has stated that the vertical fin broke away from the fuselage due to impact. Something about how the attach points were distorted and forces were assumed to come from the rear.
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Old 11th Aug 2009, 19:12
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No A330 groundings -- Worldwide-Aviation.net issues retraction:

Rectification - KLM Grounding A330 Fleet

Rectification following an article earlier today with regard to KLM suspectingly grounding its A330 fleet. Confirmed sources around the airline have told Worldwide-Aviation.net that all Airbus A330 in service of KLM are still in operation. Replacement of the pitot probes is an ongoing process and it is not expected that this would form a problem maintaining the current flight schedule.
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Old 11th Aug 2009, 22:59
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and the automated electronic messages transmitted to AF indicate a decompression event ocurred earlier?
No, they don't, certainly not explicitly, maybe read this thread back a bit first to get some proper background.
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Old 12th Aug 2009, 02:40
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As I remember (AirChina, Kalitta, and others) the 747 tends to shed outer panels of stab/elevators and gear doors with Mach+ excursions.

Not a regime that I'd ever want to explore.

Then the 747SP's were certified (as I remember) even faster than normal 747's? Maybe they operated faster, sorry, can't remember.

Do I remember that an elevator or a piece of one was recovered in the AF447 debris?
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Old 12th Aug 2009, 05:11
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Whose Else's A-300 s ??

Whilst the pitot issues have concentrated pretty much on Air France, the world fleet of 1000 A330 and A340s - and a host of other Airbuses - extends way beyond that.

What is the picture with the types of pitots in use elsewhere and any need to exchange Thales for Goodrich.

I say this with a very personal interest as I am due to fly as SLF on a Qatar Airways A330 from Doha to Manchester in 2 weeks time and would like to have some insight.

Last edited by Dave Gittins; 12th Aug 2009 at 06:11.
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Old 12th Aug 2009, 05:39
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jet aircraft equipped with thales pitot probes

Only from Airbus ?
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Old 12th Aug 2009, 16:06
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About ten years ago, an Evergreen Intl A/L 747-100 converted to cargo, enroute KJFK-KANC at night over Canada, had A/P roll computer do a slow rollover, and the plane went supersonic in the dive. They landed at nearest airport, and may have replaced a few panels. The plane continued in service for more years. Actual speed was retrieved from the fdr.

GB
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Old 12th Aug 2009, 16:20
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Avoiding too fine a point on the topic, it is of note that at least three separately discovered control surfaces were discovered. I haven't followed the drift/current discussions; BEA would conclude that the a/c impacted as a complete airframe. The Vertical Stabilizer, Rudder (attached), a spoiler (left, inner) and a portion of the Elevator were of note prior to the conclusion by BEA that the a/c held together until the last. Since the discussion is drifting in a 'shedding parts' direction, I thought I'd remind us of the evidence, though I'm not implying that is what happened. Since Upset can occur in either of two seperate trends, it appears BEA have selected the Stall rather than the overspeed, shed metal format. BEA's statement is possible, but I question its status as a conclusion.
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Old 12th Aug 2009, 16:43
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Originally Posted by Will Fraser
Since Upset can occur in either of two seperate trends, it appears BEA have selected the Stall rather than the overspeed, shed metal format. BEA's statement is possible, but I question its status as a conclusion.
Hey Will. Can't an overspeed result in a stall ? (hig speed stall/mach buffet).
Jeff
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