Airbus Story (FWIW)

John schrieb:
Loss of airspeed renders the rudder limiter inoperative, which can
lead to vertical stabilizer overstress and possible failure. This may
have happened on Flight_447. One possible solution would be to add
strain gauges that directly measure the stress in the vertical
stabilizer and feed this data to the rudder limiter along with the
airspeed and altitude information. This would allow the rudder
limiter to continue functioning even when the air-data system fails.

John wrote:

Loss of airspeed renders the rudder limiter inoperative, which can
lead to vertical stabilizer overstress and possible failure. This may
have happened on Flight_447.

Drinking too much red wine and then deliberately flying a flick roll can
also lead to empennage overstress and possible filure. This may also
have happened on Flight_447.

John Smith wrote:
John wrote:

Loss of airspeed renders the rudder limiter inoperative, which can
lead to vertical stabilizer overstress and possible failure. This may
have happened on Flight_447.

Drinking too much red wine and then deliberately flying a flick roll can
also lead to empennage overstress and possible filure. This may also
have happened on Flight_447.

So does that rule out white wine as the cause? I hope so, as I have a
slight preference for whites over reds.

What if the pilot had the fish?

On Jul 1, 7:25*am, Jim Logajan wrote:
John Smith wrote:
John wrote:


Loss of airspeed renders the rudder limiter inoperative, which can
lead to vertical stabilizer overstress and possible failure. *This may
have happened on Flight_447.

Drinking too much red wine and then deliberately flying a flick roll can
also lead to empennage overstress and possible filure. This may also
have happened on Flight_447.

So does that rule out white wine as the cause? I hope so, as I have a
slight preference for whites over reds.

What if the pilot had the fish?

Then he wouldn't have hit the pitot heat switch

On Mon, 29 Jun 2009 12:02:13 -0700 (PDT), spanky wrote:

On Jun 28, 7:36*pm, James Robinson wrote:
spanky wrote:

My understanding from the pros in other groups, is that message simply
says that the autolimiter disconnected, and as mentioned, the limits are
clamped at what they were prior to the disconnect. *It is supposedly
part of the change from normal to alternate law.


...and if the pitot tubes were providing low airspeed data (which the
OP mentioned in his post, saying "the Captains, First Officers, and
standby airspeed indicators rolled back to 60kts...") prior to the
rudder travel limiter disengage, those travel limits would be far less
stringent than if the ADC "knew" the aircraft was travelling at cruise
speed.

Is the pitot-static systems linked as in GA aircraft? If so, then a
clogged pitot would read low airspeed or am I in the dark here?
--
PWH and the Pricelessware Con Game - Exposed
http://tinyurl.com/knogy8

On Jul 1, 5:03*pm, David W wrote:

...and if the pitot tubes were providing low airspeed data (which the
OP mentioned in his post, saying "the Captains, First Officers, and
standby airspeed indicators rolled back to 60kts...") *prior to the
rudder travel limiter disengage, those travel limits would be far less
stringent than if the ADC "knew" the aircraft was travelling at cruise
speed.

Is the pitot-static systems linked as in GA aircraft? If so, then a
clogged pitot would read low airspeed or am I in the dark here?


If you meant to ask whether the 3-odd pitot systems, the answer I
think is a No, else you'd have both pilots' ASIs reporting the same
speed all the time, which isn't the case. Pilots can in fact even
choose which pitot system the Autopilot can take inputs from.

I seem to remember that one of the criticisms of the PF's actions in
the Birgen Air crash was that he didn't opt to link the AP to the
functional pitot system (FO's) although he knew right during the
takeoff roll that his own pitot had gone kaput.

Ramapriya

spanky wrote:

James Robinson wrote:

spanky wrote:

My understanding from the pros in other groups, is that message
simply says that the autolimiter disconnected, and as mentioned, the
limits are clamped at what they were prior to the disconnect. *It is
supposedly part of the change from normal to alternate law.

...and if the pitot tubes were providing low airspeed data (which the
OP mentioned in his post, saying "the Captains, First Officers, and
standby airspeed indicators rolled back to 60kts...") prior to the
rudder travel limiter disengage, those travel limits would be far less
stringent than if the ADC "knew" the aircraft was travelling at cruise
speed.

Three separate systems all roll back to the same speed identical
simultaneously? That is beyond wild speculation. As soon as one didn't
match the others, the system would cut out.

This was followed in fairly short order by a TCAS fault, an
autothrottle disconnect, a/p disconnect and institution of
alternate flight law algorithms. *
Look at the failure point of the 447 vertical
stab and compare that with the failure point of the AA 300 that
went down in 2001 on departure from JFK. *

They are different. *Not at all the same type of attachment or type
of failure.

Wrong. Both failure modes are nearly identical in apparent result
(side loads beyond design limits) and the attach fittings (composites
with steel/titanium attach points) are nearly identical as well. look
at the photographs of both verticals. there is no crushing on the
lower leading or lower trailing edges of the AF447 component that
would indicate the failure took place fore and/or aft; on the other
hand, the AF447 vertical shows skin tears along its lower edge that
would indicate that the failure mode was due to sideloads exceeding
design limits.

Wrong. The AA failure was in the attachment lugs, and the rudder was
completely missing. In the photos of the AF VS, you can see the lugs are
intact, and that the failure was in the surrounding structure, plus most
of the rudder is still attached. Further, the attachment arrangement
between the 310 and the 330 was redesigned.

Despite having a rudder travel limiter in place and working,

The A300 was not a FBW aircraft.

So what. The A300-600 has a rudder travel limiter, and its
effectiveness has been the subject of numerous NTSB Safety
Recommendations, to whit:

"A review of the flight data for rudder position showed that, even
after accounting for the slow response rate of the RTL, the rudder
still appeared to exceed the estimated position at which it should
have been limited by the RTL. This exceedance was as high as 4° near
the end of the upset. The A300-600 RTL is designed and constructed so
that it limits the rudder by reducing the allowable displacement of
the rudder pedals. Testing of the RTL determined that if a pilot
applies a sufficiently large pedal force when the pedal is at its
travel limit, this will further slow or stop the movement and,
consequently, the effectiveness of the RTL. As demonstrated by this
event, such slowing or stopping of the RTL by application of large
pedal forces could result in the rudder position substantially
exceeding the designed travel limit. The Safety Board is concerned
that such an increase in available rudder beyond the designed RTL
restrictions could permit excessive rudder movements and possibly
result in high loads on the vertical stabilizer."

My point is that the two aircraft are entirely different, as are the
controls limiting rudder travel. You might as well be trying to compare
a Boeing and an Airbus because they both have two wings and a tail.

the 2001 incident proved rather markedly that it is entirely
possible, even at climb speeds, to overstress the vertical attach
points of the structure. *...at cruise, in what may have been
beyond extreme turbulence, that possibility may indeed be a
probability in this case.

Why would an experienced pilot be using the rudder at all at cruising
speed and at that altitude?

Because the first word governing an experienced crew's reaction to an
emergency is "Aviate."

That means (especially in light of a highly experienced crew reacting
to an A/P disconnect as well as multiple warnings) put your feet on
the pedals and your hands on the yoke and fly the thing until you, and
the rest of the crew, can sort it all out. CRM 101.

Which means they wouldn't consider using the rudder at high speed and
altitude. There is practically no situation I can think of where an
experienced crew would consider using the rudder. The rudder simply isn't
used to "aviate" at altitude. Using it would be an indication of
inexperience.

We'll never know until the FDRs and CVRs are found and the data
downloaded, but on that subject I have no faith that they will be
found and, given Airbus's shenanigans with black boxes from earlier
incidents, I have no faith that the company wants them to be found.

So they will just hope no other aircraft decide to disappear while in
cruise flight? Or do you think they already know what went wrong, and
are correcting it behind the curtain?

i have no opinion one way or another. all i know is that there was a
fly-by accident at a press event years ago involving (if i recall
correctly) an A320 where, despite a TOGA command, the aircraft did not
respond and sank into the trees at the end of the runway. when the
"black boxes" were made available to the NTSB and public the serial
numbers (as well as the paint) on what were purported to be the boxes
from the accident aircraft were not the same as those that had been
installed on the accident aircraft.

You certainly do have an opinion, or you wouldn't have been posting this
stream of misinformation.

BEA is now saying that AF447 entered the water in one piece, in a
horizontal attitude, but with a high vertical force. That pretty well
describes a flat spin. That would not have happened if the VS separated
at high altitude.

http://tinyurl.com/mb4mmt
(en Francais)

And I see a number of US media sources can't translate French
aeronautical terms correctly, as they are saying the aircraft went
straight down, almost vertically.

Il paraît avoir heurté la surface de l'eau en ligne de vol

Means that the aircraft struck the surface in a horizontal attitude.

avec une forte accélération verticale"

Means with high vertical acceleration, meaning it was in an aerodynamic
stall.

James Robinson wrote:

BEA is now saying that AF447 entered the water in one piece, in a
horizontal attitude, but with a high vertical force. That pretty well
describes a flat spin. That would not have happened if the VS
separated at high altitude.

http://tinyurl.com/mb4mmt
(en Francais)

And I see a number of US media sources can't translate French
aeronautical terms correctly, as they are saying the aircraft went
straight down, almost vertically.

Il paraît avoir heurté la surface de l'eau en ligne de vol

Means that the aircraft struck the surface in a horizontal attitude.

avec une forte accélération verticale"

Means with high vertical acceleration, meaning it was in an
aerodynamic stall.

BEA is also reporting that the vertical stabilizer separated from the
aircraft from the back to front, with a slight leftward twist.

They also said that faulty pitots were a factor in the accident, but not
the cause.

Whatever conclusions you can draw from those statements.

On Jul 2, 7:18*am, James Robinson wrote:
spanky wrote:
James Robinson wrote:

(snip)

you're not a pilot, are you?