Air Transat thread (cont)
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Maybe we should wait for the FDR numbers to come out. I don't want to be anally retentive but the data put forward by Koring doesn't seem logical.
A STRAIGHT-IN approach with an initial step-down from FL 345 to 130 in 9 minutes covering a distance over the water of 137-13 km = 124km at a TAS of about 450kts.The rate of descent sounds achievable but 450kts?
Then the final 13km travelled in 12 minutes, meaning he did get within spitting distance with plenty of altitude that then needed to be bled off, belying the straight-in theory.
Sounds more like an excocet missile with a parachute than a scarebus.
A STRAIGHT-IN approach with an initial step-down from FL 345 to 130 in 9 minutes covering a distance over the water of 137-13 km = 124km at a TAS of about 450kts.The rate of descent sounds achievable but 450kts?
Then the final 13km travelled in 12 minutes, meaning he did get within spitting distance with plenty of altitude that then needed to be bled off, belying the straight-in theory.
Sounds more like an excocet missile with a parachute than a scarebus.
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What will be most interesting from the CVR and DFDR will not be the glide performance, but rather, how this Captain got into this mess in the first place. The underlying rumours, if true, are quite disturbing. Since they are still only rumours, posting them would be premature.
Wait for it!
Wait for it!
Paul Koring has written several avaition pieces for the Toronto Globe and Mail's over quite a long time. While he may be better than the average run of popular press writers on aviation, in my opinion he still has a considerable way to go.
One of his earlier pieces on this incident implies severe criticism of the pilots for leaving a crossfeed valve open. Assuming that the checklists call for the crossfeed to be open once the engine is secured (LP and HP shut) and the difficulty of seeing even a heavy leak at night, my opinion is that Koring has taken a position while important facts are still missing. But it was an eloquent article that would appeal to the general public.
One of his earlier pieces on this incident implies severe criticism of the pilots for leaving a crossfeed valve open. Assuming that the checklists call for the crossfeed to be open once the engine is secured (LP and HP shut) and the difficulty of seeing even a heavy leak at night, my opinion is that Koring has taken a position while important facts are still missing. But it was an eloquent article that would appeal to the general public.
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Rather Be Flying,
I`m not sure if you appreciate that there are TWO possible drills for the fuel leak case.
1. If the leak can be confirmed as coming from the engine then it calls for a shut down. Once that has occured the X-Feed can be opened because it is upstream of the LP valve and should not therefore pump fuel under pressure through the leak.
2. If the leak cannot be identified (probably likely in their situation) then the drill says keep X-feed closed and descend to gravity feed ceiling which in their case would be FL200. Once reaching this level ALL pumps are turned off in an attempt to minimise the fuel leak.
It would appear what they did was keep both engines running at altitude, which is rather like doing a bit of both drills.I figure if they had done EITHER drill completely they would have probably ended up doing a SE approach and landing.
Just my fourpenny worth.
I`m not sure if you appreciate that there are TWO possible drills for the fuel leak case.
1. If the leak can be confirmed as coming from the engine then it calls for a shut down. Once that has occured the X-Feed can be opened because it is upstream of the LP valve and should not therefore pump fuel under pressure through the leak.
2. If the leak cannot be identified (probably likely in their situation) then the drill says keep X-feed closed and descend to gravity feed ceiling which in their case would be FL200. Once reaching this level ALL pumps are turned off in an attempt to minimise the fuel leak.
It would appear what they did was keep both engines running at altitude, which is rather like doing a bit of both drills.I figure if they had done EITHER drill completely they would have probably ended up doing a SE approach and landing.
Just my fourpenny worth.
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Hope Keiron and the folks at ATI don't mind but they have put something together that does clear up some queries. Obviously we all await the eventual official reports but this is the best precis I've seen of what is known publicly at the moment.
Flameout stopped A330's FDR & CVR for last 20min of flight
Chris Kjelgaard, Washington DC (04Sep01, 22:44 GMT, 633 words)
Portuguese and Canadian safety officials investigating why an Air Transat
Airbus A330-200 had to make an unpowered landing in the Azores on 24 August
will be unable to derive any information from the aircraft's flight
recorders for the last 20min of the flight.
The Transportation Safety Board (TSB) of Canada confirms the flameout of
both of the A330's engines stopped the supply of electrical power to its
alternating current (AC) power buses. As in many other commercial aircraft
types, the AC buses in the A330-200 provide the electricity supply to power
both the digital flight data recorder (DFDR) and the cockpit voice recorder
(CVR).
The A330's AC power buses are supplied with electrical current by the
generators attached to each engine and by the aircraft's auxiliary power
unit (APU). In the Air Transat incident, however, the engines flamed out
because of fuel starvation following a serious fuel leak and the draining of
all fuel also meant the pilots of the aircraft were unable to use the APU to
provide electrical power.
The initial findings of the investigation, led by the Portuguese civil
aviation agency INAC, show the A330's right engine - the engine in whose
fuel supply the leak occurred - flamed out at 06:13 GMT on 24 August, but
that the left engine of the aircraft remained lit for another 13min, until
06:26 GMT.
At this point the A330 was still at an altitude of 34,000ft and was 85nm
distant from Lajes airport on the island of Terceira, at which it landed at
06:46 GMT after gliding without engine power or main electrical power for 20
min. At 06:39 GMT, 7min before landing, the aircraft was still at an
altitude of 13,000ft and was 8nm from the threshold of Lajes airport's
runway 33.
Neither the DFDF nor the CVR was operational during the last 20min of the
flight as a result of the loss of electrical power. This is not preventing
the officials investigating the incident from using the readouts from the
recorders in trying to piece together why both engines flamed out, as the
data from the period before the fuel ran out is likely to be of more
immediate importance in finding out what went wrong than what happened
afterwards.
Nevertheless, one official says that as well as understanding the Air
Transat crew's actions during the last 20min of the flight, the
post-flameout data could have been of considerable use to the investigating
agencies in modeling the flight characteristics and systems behavior of the A330 for future simulations of the aircraft in conditions of unpowered
flight.
The TSB has been concerned about interruptions in power supply to flight
data recorders of commercial aircraft ever since it began its investigation
into the crash of a Swissair MD-11 off the coast of Newfoundland in
September 1998.
In its first safety action arising from the Swissair Flight 111
investigation, the TSB recommended on 9 March 1999 that from 1 January 2005
every aircraft with a CVR offering a recording capacity of at least 2h
should have an independent power supply to power the CVR and the cockpit
area microphone for a period of 10min.
This power supply would allow the microphone and CVR to keep working
whenever the normal power source to each was interrupted.
§
The TSB also recommended that in aircraft required to have two flight
recorders, each recorder should be powered by a separate generator bus, to
minimize the possibility of an interruption in the power supply from one bus
affecting the recording capabilities of both the recorders.
In its Swissair 111 recommendations the TSB did not specifically address the
need for the DFDR in each aircraft to be linked to an independent power
supply, but the agency might review its position as a result of the findings
of the Air Transat incident.
Source: Air Transport Intelligence news
[ 05 September 2001: Message edited by: PPRuNe Towers ]
Flameout stopped A330's FDR & CVR for last 20min of flight
Chris Kjelgaard, Washington DC (04Sep01, 22:44 GMT, 633 words)
Portuguese and Canadian safety officials investigating why an Air Transat
Airbus A330-200 had to make an unpowered landing in the Azores on 24 August
will be unable to derive any information from the aircraft's flight
recorders for the last 20min of the flight.
The Transportation Safety Board (TSB) of Canada confirms the flameout of
both of the A330's engines stopped the supply of electrical power to its
alternating current (AC) power buses. As in many other commercial aircraft
types, the AC buses in the A330-200 provide the electricity supply to power
both the digital flight data recorder (DFDR) and the cockpit voice recorder
(CVR).
The A330's AC power buses are supplied with electrical current by the
generators attached to each engine and by the aircraft's auxiliary power
unit (APU). In the Air Transat incident, however, the engines flamed out
because of fuel starvation following a serious fuel leak and the draining of
all fuel also meant the pilots of the aircraft were unable to use the APU to
provide electrical power.
The initial findings of the investigation, led by the Portuguese civil
aviation agency INAC, show the A330's right engine - the engine in whose
fuel supply the leak occurred - flamed out at 06:13 GMT on 24 August, but
that the left engine of the aircraft remained lit for another 13min, until
06:26 GMT.
At this point the A330 was still at an altitude of 34,000ft and was 85nm
distant from Lajes airport on the island of Terceira, at which it landed at
06:46 GMT after gliding without engine power or main electrical power for 20
min. At 06:39 GMT, 7min before landing, the aircraft was still at an
altitude of 13,000ft and was 8nm from the threshold of Lajes airport's
runway 33.
Neither the DFDF nor the CVR was operational during the last 20min of the
flight as a result of the loss of electrical power. This is not preventing
the officials investigating the incident from using the readouts from the
recorders in trying to piece together why both engines flamed out, as the
data from the period before the fuel ran out is likely to be of more
immediate importance in finding out what went wrong than what happened
afterwards.
Nevertheless, one official says that as well as understanding the Air
Transat crew's actions during the last 20min of the flight, the
post-flameout data could have been of considerable use to the investigating
agencies in modeling the flight characteristics and systems behavior of the A330 for future simulations of the aircraft in conditions of unpowered
flight.
The TSB has been concerned about interruptions in power supply to flight
data recorders of commercial aircraft ever since it began its investigation
into the crash of a Swissair MD-11 off the coast of Newfoundland in
September 1998.
In its first safety action arising from the Swissair Flight 111
investigation, the TSB recommended on 9 March 1999 that from 1 January 2005
every aircraft with a CVR offering a recording capacity of at least 2h
should have an independent power supply to power the CVR and the cockpit
area microphone for a period of 10min.
This power supply would allow the microphone and CVR to keep working
whenever the normal power source to each was interrupted.
§
The TSB also recommended that in aircraft required to have two flight
recorders, each recorder should be powered by a separate generator bus, to
minimize the possibility of an interruption in the power supply from one bus
affecting the recording capabilities of both the recorders.
In its Swissair 111 recommendations the TSB did not specifically address the
need for the DFDR in each aircraft to be linked to an independent power
supply, but the agency might review its position as a result of the findings
of the Air Transat incident.
Source: Air Transport Intelligence news
Skybloke has commented that there are two drills for a fuel leak on the A330 depending on where the leak is identified. I would like to know what those drills are and am interested in knowing what guidance and/or instrumentation the crew has in identifying where the leak is so that they can know which drill to follow. The information in the last post that the second engine flamed out at FL340 indicates that the pumps were likely on as the maximum gravity feed altitude is FL200.
Paul Koring in today's Toronto Globe and Mail indicates that in the case of a fuel leak, the "trim" (stabiliser?) tank would first drain into the less full tank and prevent the fuel imbalance from developing until that tank is emptied -- in this case gone overboard.
In the same article, the new engine was a earlier model that AT maintenance had not installed before and found itself short of parts to conform to one service bulletion and used a procedure in another SB.
Paul Koring in today's Toronto Globe and Mail indicates that in the case of a fuel leak, the "trim" (stabiliser?) tank would first drain into the less full tank and prevent the fuel imbalance from developing until that tank is emptied -- in this case gone overboard.
In the same article, the new engine was a earlier model that AT maintenance had not installed before and found itself short of parts to conform to one service bulletion and used a procedure in another SB.
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With regard to powering the FDR when all engines are inoperative, remember you need more power than that required to run only the FDR. For the FDR data to be useful, you must also power all the sensors used to supply the FDR with data to record.
Having both engines inoperative puts a premium on available electrical power. Battery and/or RAT generated electrical power is devoted to essential flight systems needed to maintain control of the aircraft in a potential IFR environment.
A fully functional FDR would require a significantly larger set of batteries or larger/multiple RAT's. The airframe builders have been unable to see this as a good trade in terms of the increased equipment, weight and maintenance costs. After all, although the Air Transat dead stick landing was a significant piece of airmanship, the data necessary to understand the incident was recorded before the engines quit.
Having both engines inoperative puts a premium on available electrical power. Battery and/or RAT generated electrical power is devoted to essential flight systems needed to maintain control of the aircraft in a potential IFR environment.
A fully functional FDR would require a significantly larger set of batteries or larger/multiple RAT's. The airframe builders have been unable to see this as a good trade in terms of the increased equipment, weight and maintenance costs. After all, although the Air Transat dead stick landing was a significant piece of airmanship, the data necessary to understand the incident was recorded before the engines quit.
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I agree with Old Aero Guy, the high priority use of available electrical power after all engines are shut down, must be given to the critical systems and instruments that help the pilot get the aircraft down safely. All other priorities for use of the limited standby electrical power are secondary.
After thinking about this for a while, perhaps the current methods of supplying power to the FDR and CVR are correct just as they are. If the CVR unit in this aircraft has a 30 minute tape (correct me if I'm wrong about this), then the CVR stopped at just the right moment when the left engine flamed out. As others have pointed out, the events leading up to the fuel starvation of both engines, are far more important to the investigators that what happened afterwards. Because the CVR stopped when the left engine flamed out, the maximum amount of CVR data relevant to the events leading up to the fuel starvation, were preserved. BTW, I think that if anyone wants to know how an A330 performs in a glide, flight tests should be scheduled, which would provide a far better test data set wouldn't they?
To me, the most important question after what caused the fuel leak (which is already known), was what events lead to the premature fuel starvation of the left engine. This question is very critical regarding this incident, as a future event of this kind could send an aircraft into the water. The investigation may or may not implicate the pilots, but a thorough understanding of those events is crucial.
As the events unfolded, and with the FDR and CVR particularly stopping when they did, the maximum amount of data was preserved for the most critical part of this investigation. Perhaps nothing needs to be changed in the power sources of the FDR/CVR.
After thinking about this for a while, perhaps the current methods of supplying power to the FDR and CVR are correct just as they are. If the CVR unit in this aircraft has a 30 minute tape (correct me if I'm wrong about this), then the CVR stopped at just the right moment when the left engine flamed out. As others have pointed out, the events leading up to the fuel starvation of both engines, are far more important to the investigators that what happened afterwards. Because the CVR stopped when the left engine flamed out, the maximum amount of CVR data relevant to the events leading up to the fuel starvation, were preserved. BTW, I think that if anyone wants to know how an A330 performs in a glide, flight tests should be scheduled, which would provide a far better test data set wouldn't they?
To me, the most important question after what caused the fuel leak (which is already known), was what events lead to the premature fuel starvation of the left engine. This question is very critical regarding this incident, as a future event of this kind could send an aircraft into the water. The investigation may or may not implicate the pilots, but a thorough understanding of those events is crucial.
As the events unfolded, and with the FDR and CVR particularly stopping when they did, the maximum amount of data was preserved for the most critical part of this investigation. Perhaps nothing needs to be changed in the power sources of the FDR/CVR.
