There were only about 18 aircraft of all types still flying at the time and none are dedicated passenger aircraft. Indefinite grounding is the most sensible move.
Now, Boeing, et. al. are trying to evaluate the deficiencies in existing D checks and put together an inspection regime (i.e., NDT) that would proactively identify fatigue that would economically permit continued serviceable operation. If this feat turns out to be impossible for technical or cost reasons, then and only then will the grounding will become permanent.
Now, Boeing, et. al. are trying to evaluate the deficiencies in existing D checks and put together an inspection regime (i.e., NDT) that would proactively identify fatigue that would economically permit continued serviceable operation. If this feat turns out to be impossible for technical or cost reasons, then and only then will the grounding will become permanent.