A330/A340 EAD (AoA PROBES)
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A330/A340 EAD (AoA PROBES)
Somme more informations :
2 ADs edited from EASA on 2012/12/17
http://ad.easa.europa.eu/blob/AFM_TR286... 2-0264-E_1
http://ad.easa.europa.eu/blob/easa_ad_2... 2-0264-E_2
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in second AD :
Applicability:
Airbus A318-111, A318-112, A318-121, A318-122, A319-111, A319-112, A319-113, A319-114, A319-115, A319-131, A319-132, A319-133, A320-111, A320-211, A320-212, A320-214, A320-215, A320-216, A320-231, A320-232, A320-233, A321-111, A321-112, A321-131, A321-211, A321-212, A321-213, A321-231 and A321-232 aeroplanes, all manufacturer serial numbers, if Airbus modification (mod.) 153213 or 153214 has been embodied in production, or Airbus Service Bulletin (SB) A320-34-1521 has been embodied in service.
Reason:
An A330 aeroplane, equipped with Angle of Attack (AoA) sensors with conic plates installed, recently experienced blockage of all sensors during climb, leading to autopilot disconnection and activation of the alpha protection (Alpha Prot) when Mach number was increased.
Based on the results of the subsequent analysis, it is suspected that these conic plates may have contributed to the event. Investigations are on-going to determine what caused the blockage of these AoA sensors.
Blockage of two or three AoA sensors at the same angle may cause the Alpha Prot of the normal law to activate. Under normal flight conditions (in normal law), if the Alpha Prot activates and Mach number increases, the flight control laws order a pitch down of the aeroplane that the flight crew may not be able to counteract with a side stick deflection, even in the full backward position.
This condition, if not corrected, could result in reduced control of the aeroplane.
EASA issued Emergency AD 2012-0258-E to address this potential unsafe
2 ADs edited from EASA on 2012/12/17
http://ad.easa.europa.eu/blob/AFM_TR286... 2-0264-E_1
http://ad.easa.europa.eu/blob/easa_ad_2... 2-0264-E_2
must register for access EASA
in second AD :
Applicability:
Airbus A318-111, A318-112, A318-121, A318-122, A319-111, A319-112, A319-113, A319-114, A319-115, A319-131, A319-132, A319-133, A320-111, A320-211, A320-212, A320-214, A320-215, A320-216, A320-231, A320-232, A320-233, A321-111, A321-112, A321-131, A321-211, A321-212, A321-213, A321-231 and A321-232 aeroplanes, all manufacturer serial numbers, if Airbus modification (mod.) 153213 or 153214 has been embodied in production, or Airbus Service Bulletin (SB) A320-34-1521 has been embodied in service.
Reason:
An A330 aeroplane, equipped with Angle of Attack (AoA) sensors with conic plates installed, recently experienced blockage of all sensors during climb, leading to autopilot disconnection and activation of the alpha protection (Alpha Prot) when Mach number was increased.
Based on the results of the subsequent analysis, it is suspected that these conic plates may have contributed to the event. Investigations are on-going to determine what caused the blockage of these AoA sensors.
Blockage of two or three AoA sensors at the same angle may cause the Alpha Prot of the normal law to activate. Under normal flight conditions (in normal law), if the Alpha Prot activates and Mach number increases, the flight control laws order a pitch down of the aeroplane that the flight crew may not be able to counteract with a side stick deflection, even in the full backward position.
This condition, if not corrected, could result in reduced control of the aeroplane.
EASA issued Emergency AD 2012-0258-E to address this potential unsafe
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All-New AF447 Documentary 2013
Zeitgeschehen - Rio - Paris: Todesflug AF447 - N24 Dokumentationen
Vid won't play from my end.
Maybe from yours.
Vid won't play from my end.
Maybe from yours.
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I don't mean to kvetch, but wouldn't that be more appropriate in the thread about AF447? This thread's about a completely different incident.
Incidentally, it looks like there's a bug in the site's code that's causing the video to not load for now. It's likely to be fixed shortly
Incidentally, it looks like there's a bug in the site's code that's causing the video to not load for now. It's likely to be fixed shortly
Last edited by DozyWannabe; 10th Jan 2013 at 23:06.
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Unless the video was made with this:
FOQA flight animation and Simulator debriefing station - CEFA Aviation
from the FDR data .. I think it's another useless video (journalist essay) bringing nothing new about AF447 ...
FOQA flight animation and Simulator debriefing station - CEFA Aviation
from the FDR data .. I think it's another useless video (journalist essay) bringing nothing new about AF447 ...
Last edited by jcjeant; 10th Jan 2013 at 23:36.
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@OK465:
and when this is done during an alpha prot pitchdown, you can observe the elevators smoothly go full AND
From an academic point of view:
When alpha protect is triggered
- AP disconnect
- Nz law is replaced by Hi AoA Law
- Auto pitch trim is limited from entry point AoAprot. to 2° AND
- Elevator is 4° ahead AND
In this case sensed AoA = AoA prot and - due to increasing Mach - AoAprot. ~ AoAmax (this is the referred Red over Amber on speed display), hence the lack of ANU control in AFT stick.
Now if the pitch wheels are cranked up (ANU) until level, this still doesn’t change the sensed AoA (remains blocked @ AoAprot) so there will be nothing to correct for by the automatics.
I would still wonder about the aircraft response if and when the vanes unstuck with full AND elevator and some considerable degree of ANU THS trim in place when this occurred.
Definitely it will be not a smooth transition into normal Nz law.
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Originally Posted by A33Zab
Now if the pitch wheels are cranked up (ANU) until level, this still doesn’t change the sensed AoA (remains blocked @ AoAprot) so there will be nothing to correct for by the automatics.
- Elevator will trail by 4 deg
- Elevator will not move
- Elevator will fight up maybe to the max ND
- What else ?
Any other data Learmount could be given to share ?
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@OK465 & CONF
From the QF72 (AoA spikes) final report:
Table 19: Characteristics of elevator control mechanisms
High AOA protection
Control law: Normal law only
Speed: Any
Altitude:Any (must exceed threshold for at least 2 seconds when aircraft below 500 ft)
Configuration: Any
Maximum authority: 4° elevator movement (at time of pitch-downs)
Anti pitch-up compensation
Control law: Normal or alternate law
Speed: Mach 0.65 or more
Altitude: Any
Configuration: Landing gear retracted, flaps up
Maximum authority: 6° elevator movement
High angle of attack protection
Aerodynamic stall in large aircraft is a potentially dangerous condition and aircraft manufacturers incorporate design techniques to prevent it.
On the A330/340, the FCPCs continually monitored the AOAFCPC input.
If the master FCPC detected that this value exceeded a predefined threshold (alpha max), then it issued control orders for a nose-down elevator movement to reduce the AOA and prevent a stall.
High AOA protection was only available when the aircraft was in normal law.
If AOAFCPC input was outside the range of -10° to +30°, the control law reverted from normal law to alternate law, and the protection was therefore no longer available.
In addition, when the aircraft was more than 500 ft above ground level, the protection was effective immediately; when the aircraft was below 500 ft, it was only active after AOAFCPC input exceeded the threshold for 2 seconds or more.
The maximum authority or change in elevator movement that could result from the the high AOA protection varied depending on several factors.
The aircraft manufacturer reported that, at the time of the two in-flight upsets, the maximum authority was about 4° of elevator movement.
The protection would be applied until the aircraft’s AOA was reduced below the stall angle.
Anti pitch-up compensation
Anti pitch-up was a mechanism included in the A330’s control laws to compensate for a pitch-up* tendency at high Mach numbers and high AOA.
The compensation was only available above Mach 0.65 and when the aircraft was in a ‘clean’ configuration (that is, with the landing gear and flaps retracted).
Its maximum authority was 6° of elevator movement.
*
On a statically stable aircraft, the centre of lift is situated behind the aircraft’s centre of gravity and an increase in AOA would lead to an increase in lift and a restorative tendency to pitch the aircraft nose down.
However, at higher Mach numbers and AOAs, it is possible to stall the wing tips.
On a swept-wing aircraft, the centre of lift will then move forward, leading to a reduced nose-down reaction to increasing AOA, reduced stability, and a tendency to pitch up.
IMO alpha prot can be @ alpha max (in this case and normal for 5s @TO) but never beyond, with normal operating AoA vanes the alpha protect will kick in before alpha max.
Table 19: Characteristics of elevator control mechanisms
High AOA protection
Control law: Normal law only
Speed: Any
Altitude:Any (must exceed threshold for at least 2 seconds when aircraft below 500 ft)
Configuration: Any
Maximum authority: 4° elevator movement (at time of pitch-downs)
Anti pitch-up compensation
Control law: Normal or alternate law
Speed: Mach 0.65 or more
Altitude: Any
Configuration: Landing gear retracted, flaps up
Maximum authority: 6° elevator movement
High angle of attack protection
Aerodynamic stall in large aircraft is a potentially dangerous condition and aircraft manufacturers incorporate design techniques to prevent it.
On the A330/340, the FCPCs continually monitored the AOAFCPC input.
If the master FCPC detected that this value exceeded a predefined threshold (alpha max), then it issued control orders for a nose-down elevator movement to reduce the AOA and prevent a stall.
High AOA protection was only available when the aircraft was in normal law.
If AOAFCPC input was outside the range of -10° to +30°, the control law reverted from normal law to alternate law, and the protection was therefore no longer available.
In addition, when the aircraft was more than 500 ft above ground level, the protection was effective immediately; when the aircraft was below 500 ft, it was only active after AOAFCPC input exceeded the threshold for 2 seconds or more.
The maximum authority or change in elevator movement that could result from the the high AOA protection varied depending on several factors.
The aircraft manufacturer reported that, at the time of the two in-flight upsets, the maximum authority was about 4° of elevator movement.
The protection would be applied until the aircraft’s AOA was reduced below the stall angle.
Anti pitch-up compensation
Anti pitch-up was a mechanism included in the A330’s control laws to compensate for a pitch-up* tendency at high Mach numbers and high AOA.
The compensation was only available above Mach 0.65 and when the aircraft was in a ‘clean’ configuration (that is, with the landing gear and flaps retracted).
Its maximum authority was 6° of elevator movement.
*
On a statically stable aircraft, the centre of lift is situated behind the aircraft’s centre of gravity and an increase in AOA would lead to an increase in lift and a restorative tendency to pitch the aircraft nose down.
However, at higher Mach numbers and AOAs, it is possible to stall the wing tips.
On a swept-wing aircraft, the centre of lift will then move forward, leading to a reduced nose-down reaction to increasing AOA, reduced stability, and a tendency to pitch up.
Might not this constant AOA vane position, as displayed as characteristic speed, indicate an AOA condition at, or even beyond, alpha max?
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Further to A33Zab's reply -
At M=0.81 alphamax is 5 degrees, so it is quite possible that alpha max was exceeded.
However, in the QF72 accident alpha max was exceeded by a large amount. From the QF72 Final Report (5.2.2):
At M=0.81 alphamax is 5 degrees, so it is quite possible that alpha max was exceeded.
However, in the QF72 accident alpha max was exceeded by a large amount. From the QF72 Final Report (5.2.2):
The 10° nose-down elevator command was very close to the highest magnitude possible from the EFCS’s two corrective mechanisms. The second AOA spike of 50.6° resulted in the AOA value used by the FCPCs (AOAFCPC input) being 26°. If the AOAFCPC input had been over 30°, the EFCS would have reverted to alternate law, which would have resulted in one of its corrective mechanisms (high AOA protection) not being active.
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Additions (conical plates) were added to the AOA sensors to improve the functioning of these
Occurs some time after the Eva Air incident
An EAD is issued (and nothing better is find in this EAD that what the pilots of Eva Air made) "shortly" after and conical plates are eradicated
Who first decided to add these conical plates?
How (what tests) and by whom they were certified ?
This looks like the same thing to certify a improved life jacket (by adding buoyancy material) and the first who must use it sink like a stone instead of floating
Occurs some time after the Eva Air incident
An EAD is issued (and nothing better is find in this EAD that what the pilots of Eva Air made) "shortly" after and conical plates are eradicated
Who first decided to add these conical plates?
How (what tests) and by whom they were certified ?
This looks like the same thing to certify a improved life jacket (by adding buoyancy material) and the first who must use it sink like a stone instead of floating
Last edited by jcjeant; 18th Jan 2013 at 10:39.
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HKP
Do you mean a report will be finally published ?
We have so little information on this event, did you actually turn off all three ADRs ? Was the aircraft equipped with the BUSS ?
We have so little information on this event, did you actually turn off all three ADRs ? Was the aircraft equipped with the BUSS ?
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Imagining if the involved pilots turned off all three PRIMs to enter Direct Law with sidesticks already at FULL AFT postion: you will enter a high-G (no g protection now) pitch up which will result in structural damage or enter a REAL stall!
How do I know this, because I was sitting on the R/H seat instructing a new capt. Thank almighty we made ALIVE that day
How do I know this, because I was sitting on the R/H seat instructing a new capt. Thank almighty we made ALIVE that day
That said - the lack of proper training for flight crew in terms of how the systems affect the aircraft is nothing new - wasn't a contributing factor to the Adam Air 574 crash down to the Captain not realising that the systems should not be reset without the aircraft being straight and level?
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Did it happen again?
Incident: Lufthansa A321 near Bilbao on Nov 5th 2014, loss of 4000 feet of altitude
Incident: Lufthansa A321 near Bilbao on Nov 5th 2014, loss of 4000 feet of altitude
By Simon Hradecky, created Tuesday, Nov 18th 2014 17:11Z, last updated Sunday, Dec 28th 2014 22:22Z
A Lufthansa Airbus A321-200, registration D-AIDP performing flight LH-1829 from Bilbao,SP (Spain) to Munich (Germany) with 109 people on board, was climbing through FL310 out of Bilbao about 15 minutes into the flight at 07:03Z, when the aircraft on autopilot unexpectedly lowered the nose and entered a descent reaching 4000 fpm rate of descent. The flight crew was able to stop the descent at FL270 and continued the flight at FL270, later climbing to FL280, and landed safely in Munich about 110 minutes after the occurrence.
The French BEA reported in their weekly bulletin that the occurrence was rated a serious incident and is being investigated by Germany's BFU.
The occurrence aircraft remained on the ground in Munich for 75 hours before resuming service on Nov 8th.
The Aviation Herald learned that the loss of altitude had been caused by two angle of attack sensors having frozen in their positions during climb at an angle, that caused the fly by wire protection to assume, the aircraft entered a stall while it climbed through FL310. The Alpha Protection activated forcing the aircraft to pitch down, which could not be corrected even by full back stick input. The crew eventually disconnected the related Air Data Units and was able to recover the aircraft.
Following the occurrence EASA released emergency airworthiness directive 2014-0266-E_1 stating:
An occurrence was reported where an Airbus A321 aeroplane encountered a blockage of two Angle Of Attack (AOA) probes during climb, leading to activation of the Alpha Protection (Alpha Prot) while the Mach number increased. The flight crew managed to regain full control and the flight landed uneventfully.
When Alpha Prot is activated due to blocked AOA probes, the flight control laws order a continuous nose down pitch rate that, in a worst case scenario, cannot be stopped with backward sidestick inputs, even in the full backward position. If the Mach number increases during a nose down order, the AOA value of the Alpha Prot will continue to decrease. As a result, the flight control laws will continue to order a nose down pitch rate, even if the speed is above minimum selectable speed, known as VLS.
This condition, if not corrected, could result in loss of control of the aeroplane.
The EASA requires as immediate emergency action that the flight crew operating manuals must be amended with a procedure to keep only one Air Data Reference Unit operative and turning the other two off in following cases:
- the aircraft goes into a continuous nose down pitch movement that can not be stopped by full backward stick deflection
- the Alpha Max (red) strip completely hides the Alpha Prot strip (black/amber) without increase in load factor
- the Alpha Prot strip rapidly changes by more than 30 knots during flight maneouvers with increase in load factor while autopilot is on and speedbrakes are retracted
Incident: Lufthansa A321 near Bilbao on Nov 5th 2014, loss of 4000 feet of altitude
Incident: Lufthansa A321 near Bilbao on Nov 5th 2014, loss of 4000 feet of altitude
By Simon Hradecky, created Tuesday, Nov 18th 2014 17:11Z, last updated Sunday, Dec 28th 2014 22:22Z
A Lufthansa Airbus A321-200, registration D-AIDP performing flight LH-1829 from Bilbao,SP (Spain) to Munich (Germany) with 109 people on board, was climbing through FL310 out of Bilbao about 15 minutes into the flight at 07:03Z, when the aircraft on autopilot unexpectedly lowered the nose and entered a descent reaching 4000 fpm rate of descent. The flight crew was able to stop the descent at FL270 and continued the flight at FL270, later climbing to FL280, and landed safely in Munich about 110 minutes after the occurrence.
The French BEA reported in their weekly bulletin that the occurrence was rated a serious incident and is being investigated by Germany's BFU.
The occurrence aircraft remained on the ground in Munich for 75 hours before resuming service on Nov 8th.
The Aviation Herald learned that the loss of altitude had been caused by two angle of attack sensors having frozen in their positions during climb at an angle, that caused the fly by wire protection to assume, the aircraft entered a stall while it climbed through FL310. The Alpha Protection activated forcing the aircraft to pitch down, which could not be corrected even by full back stick input. The crew eventually disconnected the related Air Data Units and was able to recover the aircraft.
Following the occurrence EASA released emergency airworthiness directive 2014-0266-E_1 stating:
An occurrence was reported where an Airbus A321 aeroplane encountered a blockage of two Angle Of Attack (AOA) probes during climb, leading to activation of the Alpha Protection (Alpha Prot) while the Mach number increased. The flight crew managed to regain full control and the flight landed uneventfully.
When Alpha Prot is activated due to blocked AOA probes, the flight control laws order a continuous nose down pitch rate that, in a worst case scenario, cannot be stopped with backward sidestick inputs, even in the full backward position. If the Mach number increases during a nose down order, the AOA value of the Alpha Prot will continue to decrease. As a result, the flight control laws will continue to order a nose down pitch rate, even if the speed is above minimum selectable speed, known as VLS.
This condition, if not corrected, could result in loss of control of the aeroplane.
The EASA requires as immediate emergency action that the flight crew operating manuals must be amended with a procedure to keep only one Air Data Reference Unit operative and turning the other two off in following cases:
- the aircraft goes into a continuous nose down pitch movement that can not be stopped by full backward stick deflection
- the Alpha Max (red) strip completely hides the Alpha Prot strip (black/amber) without increase in load factor
- the Alpha Prot strip rapidly changes by more than 30 knots during flight maneouvers with increase in load factor while autopilot is on and speedbrakes are retracted
The latrst OEBs for A320F and A330/340 issued by Airbus are directly related to the Lufty incident. The incident appears to have been caused by two AOA probes producing similar but erroneous data and consequently the architecture disregarding the correct third one.
The answer to the problem is to turn off two ADR and force the aircraft into Alternate Law. The more serious question is why are AOA probes icing up in the first place?There are two types of probe I believe and it will be interesting to see which one was fitted to the Lufty aircraft.
The answer to the problem is to turn off two ADR and force the aircraft into Alternate Law. The more serious question is why are AOA probes icing up in the first place?There are two types of probe I believe and it will be interesting to see which one was fitted to the Lufty aircraft.
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information outside the box
I'm just a Silver C and NPPL type, with a logical mind.... and reduced hearing.
My car has no AoA instrumentation, probes or whatever, but in the event of speedo failure, a very accurate GPS display tells me what I need to know.
Why have Airbus missed the trick of using GPS data as a correlation reference??!!
Okay, vertical speed is less accurate than horizontal, but the math of deriving a reasonable approximation of airspeed is pretty basic, especially if there is an established figure from a period of previous flight.
Instead of horns blaring, a little note on the HSI or somewhere would tell the pilot that an approximation was being made until the pressure instruments came back on line in a few minutes... and attitude would be kept within sensible boundaries till further notice!! Equal amounts of blue and brown with a groundspeed inside a sensible historical range might be better than joystick wrestling....
I did suggest this at a CRM lecture with CAA reps present, wonder if it has been noted?
Don't tell me that the programming cannot be compromised by unverified input... after all, that's what the sidesticks are for
My car has no AoA instrumentation, probes or whatever, but in the event of speedo failure, a very accurate GPS display tells me what I need to know.
Why have Airbus missed the trick of using GPS data as a correlation reference??!!
Okay, vertical speed is less accurate than horizontal, but the math of deriving a reasonable approximation of airspeed is pretty basic, especially if there is an established figure from a period of previous flight.
Instead of horns blaring, a little note on the HSI or somewhere would tell the pilot that an approximation was being made until the pressure instruments came back on line in a few minutes... and attitude would be kept within sensible boundaries till further notice!! Equal amounts of blue and brown with a groundspeed inside a sensible historical range might be better than joystick wrestling....
I did suggest this at a CRM lecture with CAA reps present, wonder if it has been noted?
Don't tell me that the programming cannot be compromised by unverified input... after all, that's what the sidesticks are for
Level600 for clarity is that the one with a conic plate? I thought that the plates were meant to have been removed following an AD?
EASA orders Airbus angle-of-attack plate swap - 2/5/2013 - Flight Global
EASA orders Airbus angle-of-attack plate swap - 2/5/2013 - Flight Global