JF Mezei
2009-12-18 00:01:10 UTC
This is about the Air France A330 Between Rio and Paris that crashed in
the ocean on June 1 with unrecovered FDR/CVR.
http://www.bea.aero/fr/enquetes/vol.af.447/vol.af.447.php
English version of the 2nd interim report:
http://www.bea.aero/docspa/2009/f-cp090601e2.en/pdf/f-cp090601e2.en.pdf
A new search campaign for the flight recorders is hoped by Fefruary 2010.
There is a graphic on page 14 highlighting where recovered parts
belonged on the intact aircraft. They have recovers from the Radome to
the rudder in the back.
##
1.12.3.1. Cabin parts
A high degree of vertical compression can be seen on the cabin parts
such as the galleys, stowage, partitions and toilet doors. This vertical
compression is observable from the front (stowage and toilet at the
level of door 1) to the rear of the aircraft (Galley G5), and from the
right- to the left-hand sides.
Certain overhead luggage racks were found with their fuselage attachment
fittings. Besides the damage due to the vertical compression, these
fittings have deformations that are due to a forward movement of the
overhead luggage racks.
##
29 passenger O2 containers were recovered. (The box in the overhead bins
with the trap door that opens to deploy the masks). 3 of them had the
door still on, in closed position. (This would indicate that the
emrgency O2 system was not deployed).
The actual mechanism to trigger delivery of O2 was not triggered.
They could determine that 3 of them were in closed position. The
system is designed so that all O2 containers are triggered at the same
time. Depressurisation means pressure inside the cabin corresponding to
an altitude of more than 14,000 ft.
Flaps were retracted at time of impact.
The observations made on the debris (toilet doors, partitions, galleys,
cabin crew rest module, spoiler, aileron, vertical stabiliser) evidenced
high rates of compression resulting from a high rate of descent at the
time of impact with the water.
This high rate of compression can be seen all over the aircraft and
symmetrically on the right- and left-hand sides.
The deformations of the fuselage frames at the root of the vertical
stabiliser
were not consistent with an aircraft nose-down attitude at the moment of
impact.
From these observations it can be deduced that:
-The aircraft was probably intact on impact.
-The aircraft struck the surface of the water with a positive attitude,
a low bank and a high rate of descent.
-There was no depressurisation.
50 were identified. 45 pax, 4 FAs and the Captain.
Eight were seated in business class between doors 1 and 2;
-Three were seated in business class aft of door 2;
-Twelve were seated in economy forward of the over-wing exits;
-Twenty-two were seated at the rear of the airplane, between the
overwing exits and the number 3 doors.
Forty-three of the victims had fractures of the spinal column, the
thorax and the pelvis. The fractures described were located mainly at
the level of the transition vertebrae.
Ar about page 36, they start to analyse and explain each of the ACARS
messages that were received. Very informative read.
At this stage of the investigation, analysis of the messages makes it
possible to highlight an inconsistency in the speeds measured just after
2 h 10 which in that minute generated ten of the twenty-four maintenance
messages. Eleven other messages generated between 2 h 10 and 2 h 14 can
also be linked to anemometric problems (inconsistencies in the speeds,
low speeds and/or erratic speed values).
The aircraft switched to alternate 2 law in the minute at 2 h 10 and
remained in that law until the end of the flight..
No message present in the CFR indicates the loss of displays or of
inertial information (attitudes).
Page 47 in the pDF descripes the different FBW limitations (normal law,
alternate law and direct law).
This seems to be a very good explanation of the various FBW control
laws, what triggers changes etc.
In alternate law, stall protection is not available, but stall warnings
are still issued. (aka: you can use the controls to stall the aircraft).
One aspect mentioned a couple of times is the case where 1 ADR is
rejected because it is too different, but the remaining 2 are the ones
that are wrong, but because they are wrong by the same amount, the
difference between the is small enough to gate the computer to decide
that those values are the right ones.
Summary: Much time is spent analysing the air probed/pitots. Basically,
the previous cases of failure result in autopilot/autothrust disengaging
until the potos thaw again and proper data ia available to the computers
again. In cases where 2 pitos have similar errors, the computers
believe them and ay generate stall warnings because they report a speed
that is too slow.
None of the report tries to explain how the aircraft can go from level
flight to falling flat onto the ocean because of lopss of
airspeed/altitude indicators.
I find it interesting that such aircraft would not have GPS ground-speed
and altitude as inputs to the computers. Seems to me that a GPS
information would provide a sanity check for the computers. ground speed
and GPS altitude may not match airspeed and barometric altitude, but the
computer can see monitor CHANGES in the GPS data to see how it relates
to the air based sensors.
The other aspect not mentioned in the report is whether the many
airprobe failure incidents recorded for the 330/340 have their
equivalents in Boeing aircraft.
Since there are no wind tunnels to test pitots under all flight
conditions, one would think that design problems resulting in some
pitots not behaving under certain circumstances would not be specific to
one aircraft type.
--
misc.travel.air-industry is a moderated newsgroup. Please mail messages to
***@airinfo.aero, and see http://mtai.airinfo.aero for the FAQ and policies.
the ocean on June 1 with unrecovered FDR/CVR.
http://www.bea.aero/fr/enquetes/vol.af.447/vol.af.447.php
English version of the 2nd interim report:
http://www.bea.aero/docspa/2009/f-cp090601e2.en/pdf/f-cp090601e2.en.pdf
A new search campaign for the flight recorders is hoped by Fefruary 2010.
There is a graphic on page 14 highlighting where recovered parts
belonged on the intact aircraft. They have recovers from the Radome to
the rudder in the back.
##
1.12.3.1. Cabin parts
A high degree of vertical compression can be seen on the cabin parts
such as the galleys, stowage, partitions and toilet doors. This vertical
compression is observable from the front (stowage and toilet at the
level of door 1) to the rear of the aircraft (Galley G5), and from the
right- to the left-hand sides.
Certain overhead luggage racks were found with their fuselage attachment
fittings. Besides the damage due to the vertical compression, these
fittings have deformations that are due to a forward movement of the
overhead luggage racks.
##
29 passenger O2 containers were recovered. (The box in the overhead bins
with the trap door that opens to deploy the masks). 3 of them had the
door still on, in closed position. (This would indicate that the
emrgency O2 system was not deployed).
The actual mechanism to trigger delivery of O2 was not triggered.
They could determine that 3 of them were in closed position. The
system is designed so that all O2 containers are triggered at the same
time. Depressurisation means pressure inside the cabin corresponding to
an altitude of more than 14,000 ft.
Flaps were retracted at time of impact.
The observations made on the debris (toilet doors, partitions, galleys,
cabin crew rest module, spoiler, aileron, vertical stabiliser) evidenced
high rates of compression resulting from a high rate of descent at the
time of impact with the water.
This high rate of compression can be seen all over the aircraft and
symmetrically on the right- and left-hand sides.
The deformations of the fuselage frames at the root of the vertical
stabiliser
were not consistent with an aircraft nose-down attitude at the moment of
impact.
From these observations it can be deduced that:
-The aircraft was probably intact on impact.
-The aircraft struck the surface of the water with a positive attitude,
a low bank and a high rate of descent.
-There was no depressurisation.
50 were identified. 45 pax, 4 FAs and the Captain.
Eight were seated in business class between doors 1 and 2;
-Three were seated in business class aft of door 2;
-Twelve were seated in economy forward of the over-wing exits;
-Twenty-two were seated at the rear of the airplane, between the
overwing exits and the number 3 doors.
Forty-three of the victims had fractures of the spinal column, the
thorax and the pelvis. The fractures described were located mainly at
the level of the transition vertebrae.
Ar about page 36, they start to analyse and explain each of the ACARS
messages that were received. Very informative read.
At this stage of the investigation, analysis of the messages makes it
possible to highlight an inconsistency in the speeds measured just after
2 h 10 which in that minute generated ten of the twenty-four maintenance
messages. Eleven other messages generated between 2 h 10 and 2 h 14 can
also be linked to anemometric problems (inconsistencies in the speeds,
low speeds and/or erratic speed values).
The aircraft switched to alternate 2 law in the minute at 2 h 10 and
remained in that law until the end of the flight..
No message present in the CFR indicates the loss of displays or of
inertial information (attitudes).
Page 47 in the pDF descripes the different FBW limitations (normal law,
alternate law and direct law).
This seems to be a very good explanation of the various FBW control
laws, what triggers changes etc.
In alternate law, stall protection is not available, but stall warnings
are still issued. (aka: you can use the controls to stall the aircraft).
One aspect mentioned a couple of times is the case where 1 ADR is
rejected because it is too different, but the remaining 2 are the ones
that are wrong, but because they are wrong by the same amount, the
difference between the is small enough to gate the computer to decide
that those values are the right ones.
Summary: Much time is spent analysing the air probed/pitots. Basically,
the previous cases of failure result in autopilot/autothrust disengaging
until the potos thaw again and proper data ia available to the computers
again. In cases where 2 pitos have similar errors, the computers
believe them and ay generate stall warnings because they report a speed
that is too slow.
None of the report tries to explain how the aircraft can go from level
flight to falling flat onto the ocean because of lopss of
airspeed/altitude indicators.
I find it interesting that such aircraft would not have GPS ground-speed
and altitude as inputs to the computers. Seems to me that a GPS
information would provide a sanity check for the computers. ground speed
and GPS altitude may not match airspeed and barometric altitude, but the
computer can see monitor CHANGES in the GPS data to see how it relates
to the air based sensors.
The other aspect not mentioned in the report is whether the many
airprobe failure incidents recorded for the 330/340 have their
equivalents in Boeing aircraft.
Since there are no wind tunnels to test pitots under all flight
conditions, one would think that design problems resulting in some
pitots not behaving under certain circumstances would not be specific to
one aircraft type.
--
misc.travel.air-industry is a moderated newsgroup. Please mail messages to
***@airinfo.aero, and see http://mtai.airinfo.aero for the FAQ and policies.
