Svarin,
Masked faults in aircraft are nothing new. We realize you may be on to something, but we all have to realize that BEA is investigating this accident, and if they have integrity, then they will address this question in their final report. Let us hope they do.
With the highly reliable systems of today's aircraft, you can fly thousands of hours until a random event unmasks a hidden fault. Perhaps they ought to swap out which PRIM has the lead position just to unmask such potential faults. Of course, you have to give the crew the ability to quickly switch back to a stable configuration should a fault show teeth.
