Atakacs/Marciovp
Totally agree - IF it is still the case years after Taiwan that warning is extinguished even if one TL not retarded, it's an obvious question to ask AB given the previous crashes with one TR locked out. A comment was made earlier that the reported 4 "TL mishandling with one TR locked out" accidents in umpteen million flight hours may be coincidence, however we are not talking about normal ops but an apparent propensity to error when one TR locked out. We have already had 2 other reports on this thread of similar incidents from which recovery was made, so I guess it's fair to say that the confusion is a more common occurrence than just those with catastrophic consequences. This leads to the still unclear issue (from correspondence here) as to whether all operators MELs now say use both TR even if one locked, which ought presumably to help eliminate this particular combination of circumstances.
Conversely, one might also turn the issue around and ask whether there have been any more than one (Warsaw) A320 TL mishandling accidents where both TR's were functional. If not, and picking a purely hypothetical ratio of 1 in every 200 sectors where the a/c ops with a TR locked out, it would then be 800 times more likely that TL induced errors lead to accidents when one TR locked out. Please feel free to rip apart the logic at this early hour of the morning -of course 4 accidents might not be an adequate statistical sample but I wouldn't be surprised to see an AD for the AB mod mentioned..
Octavius
For non-deteriorating deferrable defects, it is quite common to use a calendar period as this allows for planning of maintenance inputs and spares delivery. If one were to use cycles/hours, the usual day to day operational aircraft changes would make forward planning more difficult. For more urgent defects, and those where further usage related deterioration is likely (e.g. brake/tyre wear or engine blade tip clearances) a cycle or hour limit is obviously appropriate.