A320 Ldg Capability
Joined: Mar 2007
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From: Here and there
With a triple sec failure the line in the fcom states that when AP is disconnected and gear down the aircraft goes into direct law, but it is rather vague about what happens if you leave the autopilot engaged. It also states the following:-
"WHEN L/G DN AND AP OFF: DIRECT LAW
If SEC 1 + 2 + 3 fail. In such a case, the LGCIU information can no longer be sent to the ELAC. For the activation of DIRECT law, the ELAC uses the condition “slats and flaps in CONF 2”, instead of “landing gear down”.
Are they saying that in this case the selection of Conf 2 will activate Direct Law and concurrently the AP will disengage because of this selection?
"WHEN L/G DN AND AP OFF: DIRECT LAW
If SEC 1 + 2 + 3 fail. In such a case, the LGCIU information can no longer be sent to the ELAC. For the activation of DIRECT law, the ELAC uses the condition “slats and flaps in CONF 2”, instead of “landing gear down”.
Are they saying that in this case the selection of Conf 2 will activate Direct Law and concurrently the AP will disengage because of this selection?
Last edited by tubby linton; 28th December 2014 at 22:41.
Only half a speed-brake
Joined: Apr 2003
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From: Commuting not home
Tubby, Vilas, please allow me to make a suggestion:
reference FCOM A320 PRO-ABN F/CTL SEC 1 (2) (3) FAULT
There are two paragraphs, for :
- triple SEC failure with A/P on
- triple SEC failure with A/P off
For both cases the text says that the ECAM will display: When [...omitted here on purpose] ... Direct Law. Then, the explanatory note goes on to say, that the DCT law will in this specific case of 3x SEC failure not come with L/G, but at CF 2. Ok, we keep this i mind.
Point 1: admitted here is, that what ECAM will show you, is not really true.
Point 2: the DCT Law "engagement" conditions are A/P off + L/G down.
What you seem to agree on is that at L/G down (cf 2 really), direct law will take over which will disconnect the A/P. The logic of FCOM seems to be different to me: a + b > c; not b > c > a.
I agree with Gryphon that there is no landing capability loss as long as AP remains engaged, the aircraft could remain in ALTN law.
reference FCOM A320 PRO-ABN F/CTL SEC 1 (2) (3) FAULT
There are two paragraphs, for :
- triple SEC failure with A/P on
- triple SEC failure with A/P off
For both cases the text says that the ECAM will display: When [...omitted here on purpose] ... Direct Law. Then, the explanatory note goes on to say, that the DCT law will in this specific case of 3x SEC failure not come with L/G, but at CF 2. Ok, we keep this i mind.
Point 1: admitted here is, that what ECAM will show you, is not really true.
Point 2: the DCT Law "engagement" conditions are A/P off + L/G down.
What you seem to agree on is that at L/G down (cf 2 really), direct law will take over which will disconnect the A/P. The logic of FCOM seems to be different to me: a + b > c; not b > c > a.
I agree with Gryphon that there is no landing capability loss as long as AP remains engaged, the aircraft could remain in ALTN law.
Joined: Jun 2007
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From: Wanderlust
Gryphon
Triple sec fail and all spoilers fail are only two failures out of twenty four when you transition to alternate law but AP is available. In A320 flare mode of alternate law is direct law. So autopilot is out of question for landing, even for manual landing you need direct law. All alternate law landings are done in direct law when gear down.
Triple sec fail and all spoilers fail are only two failures out of twenty four when you transition to alternate law but AP is available. In A320 flare mode of alternate law is direct law. So autopilot is out of question for landing, even for manual landing you need direct law. All alternate law landings are done in direct law when gear down.
Joined: Nov 2002
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From: Europe
Sorry Vilas, my fault. I wrote Normal Law and is Alternate Law with AP ON. 
About AP and landing capability, again I cannot provide any reference. In others words, I'm not defending anything, but because the QRH not mentioning the SEC,s for CAT II and CAT III, during a simulator training I requested this situation to the trainer. Autoland with CAT III Dual was performed. For me this is not enough: not the real aircraft and no documentation.
I was just curious why QRH is taking into account ELAC,s and FAC,s but not SEC,s for CAT II/III.
About AP and landing capability, again I cannot provide any reference. In others words, I'm not defending anything, but because the QRH not mentioning the SEC,s for CAT II and CAT III, during a simulator training I requested this situation to the trainer. Autoland with CAT III Dual was performed. For me this is not enough: not the real aircraft and no documentation.
I was just curious why QRH is taking into account ELAC,s and FAC,s but not SEC,s for CAT II/III.
Only half a speed-brake
Joined: Apr 2003
Posts: 4,459
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From: Commuting not home
Vilas, I seem to recall there was one special case for which this was not true and the fact was on purpose pointed out during the TR training. True/false? Thanks a lot.
Gryphon:
the FCOM procedure I posted does not show CAT3 in the INOP SYS list. This is in line, I believe, with your observations from QRH. And the limitations section does not prohibit us from autoland with CAT2+
LIM for ILS AUTOMATIC LANDING IN CAT I OR BETTER WEATHER CONDITIONS:
puzzled,
FD.
but also:
DSC-27-20-20 C: ALTERNATE LAW
FLARE MORE
In pitch alternate law the flight mode changes to the flare mode when the pilot selects landing gear down. The flare mode is a direct stick-to-elevator relationship. (Refer to DSC-27-20-20 Direct Law).
PRO-SUP-27-30 G: ABNORMAL CONTROL LAWS - IN DETAIL
ALTERNATE LAW > PITCH
As mentioned above, ALTERNATE reverts to DIRECT law for landing when the flight crew lowers the landing gear.
Gryphon:
the FCOM procedure I posted does not show CAT3 in the INOP SYS list. This is in line, I believe, with your observations from QRH. And the limitations section does not prohibit us from autoland with CAT2+
LIM for ILS AUTOMATIC LANDING IN CAT I OR BETTER WEATHER CONDITIONS:
‐ At least CAT2 capability is displayed on the FMA, and CAT II/III procedures are used.
FD.
but also:
DSC-27-20-20 C: ALTERNATE LAW
FLARE MORE
In pitch alternate law the flight mode changes to the flare mode when the pilot selects landing gear down. The flare mode is a direct stick-to-elevator relationship. (Refer to DSC-27-20-20 Direct Law).
PRO-SUP-27-30 G: ABNORMAL CONTROL LAWS - IN DETAIL
ALTERNATE LAW > PITCH
As mentioned above, ALTERNATE reverts to DIRECT law for landing when the flight crew lowers the landing gear.
Joined: Jun 2007
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From: Wanderlust
Flight Detent
The only exception in A320 is with sharklet fitted aircraft where FAC and Yaw damper failures the A/C goes in alternate law but with gear down does not go to direct law. I personally asked airbus they replied to me that in sharklet aircraft with these failures, because of the improved flight control computers the aircraft actually remains in normal law with flare mode available. If it was shown as normal law the crew might treat these failures as insignificant so is shown as alternate law.
The only exception in A320 is with sharklet fitted aircraft where FAC and Yaw damper failures the A/C goes in alternate law but with gear down does not go to direct law. I personally asked airbus they replied to me that in sharklet aircraft with these failures, because of the improved flight control computers the aircraft actually remains in normal law with flare mode available. If it was shown as normal law the crew might treat these failures as insignificant so is shown as alternate law.
Joined: Jul 2020
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From: India
Flight Detent
The only exception in A320 is with sharklet fitted aircraft where FAC and Yaw damper failures the A/C goes in alternate law but with gear down does not go to direct law. I personally asked airbus they replied to me that in sharklet aircraft with these failures, because of the improved flight control computers the aircraft actually remains in normal law with flare mode available. If it was shown as normal law the crew might treat these failures as insignificant so is shown as alternate law.
The only exception in A320 is with sharklet fitted aircraft where FAC and Yaw damper failures the A/C goes in alternate law but with gear down does not go to direct law. I personally asked airbus they replied to me that in sharklet aircraft with these failures, because of the improved flight control computers the aircraft actually remains in normal law with flare mode available. If it was shown as normal law the crew might treat these failures as insignificant so is shown as alternate law.
Thanks
