That would be the case, for example, in the situation where it was revealed by the manufacturer of the aircraft comprising the fleet of the air carrier concerned, or by a competent authority, that those aircraft, although already in service, are affected by a hidden manufacturing defect which impinges on flight safety.
See on nii näiteks olukordades, kus asjaomase lennuettevõtja lennukipargi moodustavate lennukite tooja või pädev ametiasutus avastab, et need lennukid – olgugi et juba kasutuses – on varjatud tootmisdefektiga, mis mõjutab lennuohutust.