Originally Posted by
Becky330
accidental setting to a date too far ahead in the future would trigger the WTBs...
...Is there any truth to this at all?
Yes, such was the feature. To prevent flying the plane past the deadline of a functional check, there was a timer to engage the lock automatically. Once triggered you could not restore it back by just fixing the date and engineers were needed.
My original airline acquired aeroplanes mostly with GPS clock, hence we avoided learning first hand. The recollection above is based on shared knowledge and tips from the day zero batch of Airbus factory instructors. On the non-GPS clock equipped planes sometimes the CFDS would lose sync with the main clock and software confusion ensued across the FMGS circuits. Attempts to synchronize those back was the hazard area.