A320 Ldg Capability

[Harry Cane]

Hello, need some info about A320 landing capability with 2 SECs inop. Not able to find any reference on QRH and FCOM.
Cheers.

[tubby linton]

Usually any double failure will typically result in alternate law and CAT 1.

[vilas]

Double sec does not cause alternate law. Triple sec would but you have auto pilot.

[Skornogr4phy]

Triple Sec just makes me fall over giggling:}

[tubby linton]

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?

[vilas]

tubby linton
Yes.

[tubby linton]

Thank you Vilas.

[Gryphon]

Sorry but I don't think so, although I cannot be sure.

If you keep the AP engaged you will stay in normal law, and I would say you can even make an autoland.

Again, I cannot provide any reference :(

[FlightDetent]

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.

[Gryphon]

The aircraft will remain in Normal Law as long as AP remains engaged.

And check the QRH "Required equipment for CAT II and CAT III" : Nothing about the SEC,s :confused:

[FlightDetent]

Mr. G, for 1+2+3 failure the book indicates that ALTN law will come, because the protections are lost.


http://i62.tinypic.com/radbt3.png
http://i61.tinypic.com/2cor821.png

[vilas]

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.

[Gryphon]

Sorry Vilas, my fault. I wrote Normal Law and is Alternate Law with AP ON. :O

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.

[FlightDetent]

All alternate law landings are done in direct law when gear down. 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:‐ At least CAT2 capability is displayed on the FMA, and CAT II/III procedures are used.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.

[vilas]

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.

[Piyush Arora]

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.

Can you please share the correspondence you had with Airbus??
Thanks