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AF447 And Airbus Flight Testing  
User currently onlineflyingturtle From Switzerland, joined Oct 2011, 2330 posts, RR: 13
Posted (1 year 1 month 2 weeks 1 day 8 hours ago) and read 6551 times:

Hiho dear a.nutters,


The 350 flight testing and the air-to-air-shots from the chase plane reminded me of something.

In the final report on Air France flight 447, BEA wrote that Airbus sent a similarly loaded 330 on a test flight in order to investigate the kind of nose-up descent that happened in June 2009.

Is there any technical report or even a video of this flight?


Curiously,


David


Keeping calm is terrorism against those who want to live in fear.
21 replies: All unread, jump to last
 
User currently offlinewingscrubber From UK - England, joined Sep 2001, 845 posts, RR: 0
Reply 1, posted (1 year 1 month 1 week 2 days 20 hours ago) and read 6034 times:

I don't imagine Airbus would let flight testing footage of that nature get out into public domain, the whole point of 'envelope protection' is supposed to be that they're unstallable. But I did find this-

http://www.youtube.com/watch?v=wvHzvZJnqS4



Resident TechOps Troll
User currently offlineRoseflyer From United States of America, joined Feb 2004, 9509 posts, RR: 52
Reply 2, posted (1 year 1 month 1 week 2 days 19 hours ago) and read 5985 times:

Quoting flyingturtle (Thread starter):

Is there any technical report or even a video of this flight?

I doubt that is public. Flight test data is rarely shared unless it is used for marketing purpose. Doing stall recover maneuvers rarely falls into that domain, although there are some videos of 777s stalling that were part of a PBS documentary during 777 certification.

I am sure Airbus has videos of stalling A330s. Although envelope protection exists in the real world, stall recovery is a required part of flight testing, so they do have experience stalling the airplane even if they had to use “red label” flight controls software that overrode envelope protections.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineTom_EDDF From Germany, joined Apr 2000, 451 posts, RR: 0
Reply 3, posted (1 year 1 month 1 week 4 hours ago) and read 5730 times:

Quoting wingscrubber (Reply 1):

I don't imagine Airbus would let flight testing footage of that nature get out into public domain, the whole point of 'envelope protection' is supposed to be that they're unstallable. But I did find this-

http://www.youtube.com/watch?v=wvHzv...JnqS4

I agree such footage, if available, would not be released. The point about envelope protection is irrelevant though, as it should be known that AF447 reverted to "Alternate Law", therefore both bank and high AoA protection were lost. It is commonly known that an FBW Airbus for sure can be stalled, for sure in Alternate Law/Direct Law.

[Edited 2013-06-23 03:38:45]

User currently onlineflyingturtle From Switzerland, joined Oct 2011, 2330 posts, RR: 13
Reply 4, posted (1 year 1 month 6 days 23 hours ago) and read 5649 times:

Quoting wingscrubber (Reply 1):
Quoting Roseflyer (Reply 2):

Thank you - I've already watched that video. But Airbus could publish that video, with the message that their test pilots are not shy about recreating a flight that cost hundreds of lives, and that an A330 can be saved in a AF447-like situation.


David



Keeping calm is terrorism against those who want to live in fear.
User currently onlineKlaus From Germany, joined Jul 2001, 21415 posts, RR: 54
Reply 5, posted (1 year 1 month 6 days 3 hours ago) and read 5478 times:

Quoting flyingturtle (Reply 4):
Thank you - I've already watched that video. But Airbus could publish that video, with the message that their test pilots are not shy about recreating a flight that cost hundreds of lives, and that an A330 can be saved in a AF447-like situation.

As far as I'm aware they've stalled all the FBW aircraft models during regular flight testing (not fully into the stall, but far enough to know where the boundary really is and whether it matches simulations). So additional test flights would probably just have been for additional validation.

The problem with AF447 was not that the aircraft exhibited any surprising stall behaviours, as far as I'm aware, but the problematic reactions of the crew to the generally predictable and expected behaviour under the circumstances.

The aircraft remained controllable to the end – it just wasn't controlled properly.

Whether and if so how much even a confused crew could have been helped by technical modifications while not jeopardizing other accident-free flights can be a question, but it's definitely not a simple one.


User currently onlineStarlionblue From Greenland, joined Feb 2004, 17002 posts, RR: 67
Reply 6, posted (1 year 1 month 6 days 3 hours ago) and read 5456 times:

Quoting Klaus (Reply 5):
The problem with AF447 was not that the aircraft exhibited any surprising stall behaviours, as far as I'm aware, but the problematic reactions of the crew to the generally predictable and expected behaviour under the circumstances.

The aircraft remained controllable to the end – it just wasn't controlled properly.


        

Indeed. Flight testing by Airbus seems redundant for this situation.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently online7BOEING7 From United States of America, joined Oct 2012, 1508 posts, RR: 8
Reply 7, posted (1 year 1 month 6 days ago) and read 5405 times:

Quoting Klaus (Reply 5):
As far as I'm aware they've stalled all the FBW aircraft models during regular flight testing (not fully into the stall, but far enough to know where the boundary really is and whether it matches simulations).

For certification even on FBW airplanes you need to do full stalls not just nibble at the edge to insure there are no unexpected results.


User currently offlinezeke From Hong Kong, joined Dec 2006, 8872 posts, RR: 75
Reply 8, posted (1 year 1 month 5 days 23 hours ago) and read 5396 times:

Quoting flyingturtle (Thread starter):

There will be a report, and it would have a lot of data, and more than likely footage. Probably the BEA has access to it, however it would be commercially sensitive.

The aircraft is first stalled in direct law, then retested in the various laws until normal law is active. This was a requirement for the A330 to be certified in the first place.

Flight testing does not attempt to cover every conceivable combination of attitude, airspeed, and altitude the aircraft will ever experience. Any pilot can with some effort can place an aircraft in a situation for which it is not designed, that aircraft could be a simple C172 or a complex aircraft like the A330.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently onlineStarlionblue From Greenland, joined Feb 2004, 17002 posts, RR: 67
Reply 9, posted (1 year 1 month 5 days 23 hours ago) and read 5393 times:

Quoting zeke (Reply 8):
Flight testing does not attempt to cover every conceivable combination of attitude, airspeed, and altitude the aircraft will ever experience. Any pilot can with some effort can place an aircraft in a situation for which it is not designed, that aircraft could be a simple C172 or a complex aircraft like the A330.

Well put.

I like to put it thus: A determined pilot can crash the safest airplane in the world. This is why I trust CX, SQ and QF way beyond Airbus or Boeing. The vast majority of accidents are "caused" by the pilots so why do we talk about types being unsafe.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineKarelXWB From Netherlands, joined Jul 2012, 10826 posts, RR: 31
Reply 10, posted (1 year 1 month 4 days 18 hours ago) and read 5144 times:

Quoting Klaus (Reply 5):
The problem with AF447 was not that the aircraft exhibited any surprising stall behaviours, as far as I'm aware, but the problematic reactions of the crew to the generally predictable and expected behaviour under the circumstances.

In fact, if the PF had released the joystick, the aircraft would have leveled itself. Even in alternate law.



Only two things are infinite, the universe and human stupidity. And I'm not sure about the universe.
User currently offlineChaosTheory From United Kingdom, joined Mar 2013, 229 posts, RR: 0
Reply 11, posted (9 months 3 days 14 hours ago) and read 3716 times:

Quoting flyingturtle (Thread starter):
Is there any technical report or even a video of this flight?

During the joint Airbus and Boeing stall testing lecture at the Royal Aero Society in London, a number of stall test videos were shown. The videos included the 787, 777, A380 and A330 models.

I seem to recall that the A330 stall was characterised as "benign", and apart from cockpit vibration (which could make instruments unreadable), the stall tests were uneventful (similar to the 787).

It was interesting to see the A380 and 777 exhibit rapid roll tendencies under certain conditions. On one occasion during the 777 stall testing, it swung into a bank in excess of 80 degrees before John Cashmann managed to regain wings level.

There is a video of the lecture on youtube. Unfortunately however, the stall test videos have been edited out.

Exclusive: Joint Airbus & Boeing flight test lecture


User currently offlinebueb0g From United Kingdom, joined Jul 2010, 642 posts, RR: 0
Reply 12, posted (9 months 3 days 5 hours ago) and read 3555 times:

Quoting KarelXWB (Reply 10):
In fact, if the PF had released the joystick, the aircraft would have leveled itself. Even in alternate law.

Oft quoted bit of information with no evidence whatsoever to support it. Note that the PF was not pulling fully back on the stick - he only hit he aft stop once or twice. For most of the stall, the stick was quite near centred and on two occasions was in a nose down position. Nowhere in the report does it state that the aircraft would have recovered had the pilots left the stick in the neutral position - even had the aircraft "levelled" itself, that would not have been enough to un-stall. Once through 33,000 feet a full and maintained stall recovery was required to save the aircraft.



Roger roger, what's our vector, victor?
User currently offlinenomadd22 From United States of America, joined Feb 2008, 1832 posts, RR: 0
Reply 13, posted (9 months 3 days 3 hours ago) and read 3512 times:

Quoting Starlionblue (Reply 9):
I like to put it thus: A determined pilot can crash the safest airplane in the world.

You should read the final report on John Denver's last flight. He found a way to stall an unstallable LongEze that I'm pretty sure nobody could have ever predicted.



Andy Goetsch
User currently onlineflyingturtle From Switzerland, joined Oct 2011, 2330 posts, RR: 13
Reply 14, posted (9 months 2 days 23 hours ago) and read 3382 times:

Quoting ChaosTheory (Reply 11):

Thank you, I'll watch that lecture soon!


David



Keeping calm is terrorism against those who want to live in fear.
User currently offlineKarelXWB From Netherlands, joined Jul 2012, 10826 posts, RR: 31
Reply 15, posted (9 months 2 days 21 hours ago) and read 3331 times:

Quoting bueb0g (Reply 12):
Oft quoted bit of information with no evidence whatsoever to support it. Note that the PF was not pulling fully back on the stick - he only hit he aft stop once or twice. For most of the stall, the stick was quite near centred and on two occasions was in a nose down position. Nowhere in the report does it state that the aircraft would have recovered had the pilots left the stick in the neutral position - even had the aircraft "levelled" itself, that would not have been enough to un-stall. Once through 33,000 feet a full and maintained stall recovery was required to save the aircraft.

I did not say the aircraft would recover, they have a stall recovery procedure for that. But the A330 can level off when you leave the stick alone.



Only two things are infinite, the universe and human stupidity. And I'm not sure about the universe.
User currently offlineWingedMigrator From United States of America, joined Oct 2005, 2212 posts, RR: 56
Reply 16, posted (9 months 9 hours ago) and read 2893 times:

Quoting flyingturtle (Reply 4):
with the message that their test pilots are not shy about recreating a flight that cost hundreds of lives

Nobody is going to re-create that flight, at least nobody who cares about surviving.

Quoting 7BOEING7 (Reply 7):
For certification even on FBW airplanes you need to do full stalls not just nibble at the edge to insure there are no unexpected results.

There is a wide margin between a "full stall" and flying the airplane at 45-60 degree AoA for several minutes.


User currently offlineferpe From France, joined Nov 2010, 2800 posts, RR: 59
Reply 17, posted (9 months 7 hours ago) and read 2871 times:

Quoting WingedMigrator (Reply 16):
There is a wide margin between a "full stall" and flying the airplane at 45-60 degree AoA for several minutes.

Indeed there is, once into the deep stall the risk of getting into rotation scenarios ie spin (which is more difficult to get out of if not sometimes damn hard ) is there. Noone goes into spin without having prepared that very well. For test flights of the spin domain you have a anti spin chute on the tailcone, should the fin and rudder turn out to not be effective  Wow! .



Non French in France
User currently offlineChaosTheory From United Kingdom, joined Mar 2013, 229 posts, RR: 0
Reply 18, posted (8 months 4 weeks 1 day 22 hours ago) and read 2789 times:

Quoting ferpe (Reply 17):
For test flights of the spin domain you have a anti spin chute on the tailcone, should the fin and rudder turn out to not be effective

Or, in the case of the A400M, a rocket!


User currently offlinejollo From Italy, joined Aug 2011, 212 posts, RR: 0
Reply 19, posted (8 months 3 weeks 5 days 21 hours ago) and read 2386 times:

Quoting KarelXWB (Reply 15):
But the A330 can level off when you leave the stick alone.

Genuine question: is this also true when in Alternate Law? And would it be a FBW action of just the effect of dynamic longitudinal stability?


User currently offlineKarelXWB From Netherlands, joined Jul 2012, 10826 posts, RR: 31
Reply 20, posted (8 months 3 weeks 5 days 21 hours ago) and read 2380 times:

Quoting jollo (Reply 19):
Genuine question: is this also true when in Alternate Law?

As far as I know, yes. Per pilot comments, the airplane react about the same as in Normal Law; you basically lose the flight envelope protections in Alternate Law.

http://www.airbusdriver.net/airbus_fltlaws.htm



Only two things are infinite, the universe and human stupidity. And I'm not sure about the universe.
User currently offlinejollo From Italy, joined Aug 2011, 212 posts, RR: 0
Reply 21, posted (8 months 3 weeks 4 days 23 hours ago) and read 2227 times:

Quoting KarelXWB (Reply 20):
the airplane react about the same as in Normal Law; you basically lose the flight envelope protections in Alternate Law

http://www.airbusdriver.net/airbus_f...s.htm

Very useful summary, thanks a lot.

Quote:
In pitch alternate law the flight mode is a load factor demand law similar to the Normal Law flight mode, with reduced protections.

So if you leave the stick alone you're basically demanding 1 g, and that (barring peculiar parabolic trajectories) will eventually bring the a/c back to level flight. Right?


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