"Out of an abundance of caution, following the AFSOC operational stand down, NAVAIR is instituting a grounding bulletin for all V-22 Osprey variants Dec. 6. This decision comes after the V-22 Osprey mishap on Nov. 29, off the shore of Yakushima, Japan," the release said on Wednesday.
Preliminary investigation information indicates a potential material failure caused the mishap, but the underlying cause of the failure is unknown at this time, the release added.