This is an obvious engineering response to the first few reports. Of course the get a bit exasperated when a swapped FAC from another aircraft gives same problems and the problem FAC in the donor aircraft FAC works OK.

If you are experienced airbus FBW driver, please consider suggesting final operating responsibility

It will come down to following a troubleshooting protocol. I would hope that this included swapping positions or exchanging units between aircraft. If you were unlucky you could have a pool of rogue FAC.
I am not an engineer but I do remember some obscure problems with Airbus 300-600 fuel computers that caused faults and were returned by the overhaul company with no fault found on bench testing. They would fail on fit when put back into the aircraft and I don't think that the exact cause of the failures was ever discovered before the aircraft were retired. Sometimes they would work fine on the ground but a few hours of cold soak soon started the failures again.
as to final responsibility it would be difficult to reject an aircaft for service if the log shows no faults but I would read the corrective actions in the log very carefully to see what fault finding had taken place.
The A320 family relies on engineers interrogating systems through the mcdu to troubleshoot systems and a lot of the old fashioned engineering practices and knowledge are slowly becoming a lost art,imho.

Troubleshooting...
 

...of failed components shouldn't blindly progress past the second changed computer. Not in a fleet that has normal reliability figures for that component. I mean, what are the chances of two bad ones, let alone a third? After that the related sensors, antenae, wiring, switches etc should become the focus. Or perhaps the repair procedures.

Often a fault will be traced back to some long-forgotten part change or procedure performed just before the saga of intermittent defects started. (Always check the last thing you did)

Small Fleet? Indonesian Air Asia has 29 A320, Air Asia Group has 182 with another 475 on order.

It is currently an Airbus only airline group. Previously it flew 737-300s, up until 2010 it was banned from EU air space.

The ex-military pilots certainly do not set the bar in my airline. Many perform below average. Traits required for military selection do not necessarily transfer well to the multi-crew conservative approach required for safe airline flight.

Derfred,
The military captain did not need to overcome FACs' failures in his F-16 life. Once again Airbus systems are poor copies of the F-16 systems.:}

Although it is already confirmed that the captain did not get out of his seat to pull the CB (this can not be 100% trusted IMO), I want to point out on thing. CBs are not "normal" controls and there is not CB schematic availible to the pilots (I guess maintenance has it, because they use CBs more often - but to pilots its not a normal control). I'm wondering why the captain should have known the location of the FAC cb and was therefore able to find is quickly? Yesterday I looked for it during a long ground stop just out of curiosity and it took me around 2 minutes to locate it. I can image that an experienced captain knows the location of the CBs that are used from time to time (approved reset procedures, that occur rather often...) - for example I know the location of the FMGC 1 + 2 CB by heart (I'm still a rather new FO on the A320), because I needed to use them several times already (but of course I didn't do the reset by heart, but with reference to the approved procedure in the manual!). However as several people already pointed out there is no approved FAC reset procedure involving the use of the CB, the only approved reset (for flight crew) is done with the FAC pushbutton.

Flo,
If they were already eight problems with FACs, they learned where the CB was !

There are 2 FACs, normally FAC 1 is in use and FAC 2 is in standby. If a failure is detected on any channel of FAC 1, FAC 2 takes over the corresponding channel.

When a FAC is disengaged (push button set to off) but still valid, the flight envelope function of the FAC remains active.

Flight Envelope Function:
1. PFD speed scale management
Min/max speed computation
Manoeuvring speed computation
2. Alpha-floor protection.

FAC 1 must be serviceable for dispatch, FAC 2 may be inoperative with certain conditions.

The FCOM provides for FAC resetting by switching off and back on, there is no procedure involving pulling circuit breakers.

FAC 1 CBs are on the overhead panel and reachable from the seats, FAC 2 CBs are on the rear panel and couldn't be reached from the Captains seat.

Even if both FACs failed the immediate problems would be limited to flying in alternate law with protections lost, max speed 320kts and rudder with care above 160kts. There are further considerations for landing but these would not have been immediate.

Having spent a number of years closely associated with Naval Aviation maintenance on what are now ancient aircraft the following observations may be relevant.
The worst troubleshooting problems tend to be in things like connectors, and damaged wire bundles. In cases where the box has to slide in to a rack and mate to a connector on the back side, things like recessed pins and bent pins can do weird things to connections. Even a minor obstruction could keep a box from fully seating on its associated connector with rear mount connections.

Wires can be open, shorted, or cross connected to another wire. Flexing of the airframe and unequal thermal expansion between wires and airframe can impose stresses that eventually damage improperly positioned wire bundles as can adjacent maintenance activity. Access and visibility are typically difficult in aircraft and can mask otherwise simple problems.

Intermittent problems are particularly difficult because they generally do not present themselves for correction on the ground. It frequently can require someone with an electrical engineering background to infer what the problem must be based on the symptoms. In those cases, the more data, the better.
Aviation has relied on easily replaceable boxes to facilitate maintenance for many years, and the advent of computerized troubleshooting improves the odds of fixing a problem accurately but airframe side of the interface problems are another story. Problem is, unsolved technical problems can add to the Swiss Cheese holes that eventually cause an accident.

I don't know if this issue has been floated yet, so forgive me if I missed it.

We'll know soon enough from the recording when it's released, but I'm wondering if a contributing factor might have been a native language difference between the Captain trying to deal with the avionics, and the FO flying the plane while everything was starting to go pear shaped.

If the Captain was about to do something in altering the flight computer controls, was he able to communicate that clearly to the pilot who had his hand on the stick? Factor in all the usual difficulties and stress in turbulence, unusual attitude, G-force, etc.

This may not have anything to do with what happened, but with two pilots from dissimilar native language backgrounds, I think it's worth considering.

Summary : two unstallable airbusses stalled and fell into the sea.

There is thus something wrong with the flight control systems.

Bottom line.

Autoflight...

Not an A320 pilot, but allow me to observe that different organisations have different informal standards of behaviour. And that, from time to time, senior people can be observed doing something that a more conservative person wouldn't. Gradually, the less conservative behaviour becomes the norm.

Earlier in life I was a contract pilot for a few years and got a chance to observe that there were no universally accepted behaviours for things like thunderstorm avoidance, acceptable defect reporting standards, punctuality pressures etc.

We are typically guided by the DDG, but in cases of repeated defects which ground test serviceable the evidence of prior success cannot help but inform your risk picture. Its hard to argue with certain things unless, like me, you are an assh*le.

African Skies:

There was an equipment failure on AF447 and it's looking like an equipment failure on QZ8501. So your assertion lacks any foundation.

Not that it ever had any foundation anyway.

It even is OK for any aircraft to have some "quirks" and it is OK not to redesign if you discover them, as long as the overall accident statistics are fine and the change would even add more confusion to those used to the "quirks". It is quite typical to use some flying techniques which are not exactly textbook style because of design peculiarities, the "Boeing push" comes to mind for example.
The only important point is that you acknowledge that some points of your design might be a bit special or tricky, and include them in detail in the handbooks and in the training syllabus. If pilots are fully aware and trained accordingly, any design feature can be safe. If pilots are poorly informed and trained, even simple and straightforward design features might be a major risk. An airplane alone is never "wrong", only in combination with the pilot training it may be.

Photonic
 

I do not believe that one, such pairings are now common place. We have over 25 different nationalities working in my company, and in 40 years of OPS not a single serious incident was reported having native language diffrence as a contributing cause.
Culture maybe , but language, no.

"An airplane alone is never "wrong", only in combination with the pilot training it may be."

More pilot training costs money so forget that. Pilot hands on skills are deteriorating because of manufacturerers and airlines discouraging non autopilot operation.

Monitoring an autopilot for thousands of hours does not build or maintain basic piloting skills.

perhaps not in your company but language barrier in the cockpit was cited as a contributing cause in the Helios flight 522 crash, the precedence was set.

What initiated the zoom climb?
 

The answer to the key question is answered to the investigators since a long time because they have all the elevator and stick FDR data in front of them:

What initiated the zoom climb?
a) pilot pulling the stick (input recorded by FDR)
b) weather, without stick input (input not recorded by FDR)
c) elevator input by a malfunctioning unit (input recorded by FDR)
d) sort of other mishandling

As there is no AOT out there about tech malfunctions the answer is obvious

Agreed. Sifting for minutiae misses the point. And there are already many things to learn by many parties. The report will try to pin the blame on some chain of causality ... but if we want safer skies then there are already many things to learn, by many parties. Tracking, air traffic control, search and rescue, manufacture, human-computer interface etc...

The business / marketing side of things seems also very important; from what I understand flight control systems were an important factor in Airbus's entry to market, to give it something new to edge into a mostly (at that time) Boeing market.