While investigators have satisfied the U.S. Marine Corps brass that an April 11 fatal MV-22B Osprey crash was not due to mechanical or material failures and that there were no issues with the safety of the aircraft itself, the service still needs to show Japanese leaders the tiltrotor fleet is safe to operate there.

The Marines have deployed about a dozen Ospreys to Japan but have yet to use them for normal operations because of concerns among the country’s leaders about the safety of the aircraft given relatively recent crashes and other mishaps.

In an effort to prove that Osprey operations are safe, Marines briefed Japanese leaders about their findings on the April accident, which took place in Morocco, Africa, near a landing zone as pilots wrestled with the aircraft above a congested area in tough wind conditions.

While Japanese officials reportedly agreed with the Marines’ assessment, the Osprey’s flights still are being curtailed.

“Our governments continue to work closely together to enable reconfirmation of MV-22 flight safety and subsequent flight operations,” says Lt. Col. Dave Griesmer, director of the public affairs office for Marine Corps Installations Pacific, III Marine Expeditionary Force, in an Aug. 31 email.

Griesmer would neither confirm nor deny Japanese newspaper reports that the Marines plan to offer flights on MV-22s for local leaders so they can feel safe about the aircraft.

The proposed flights at the Marines’ Iwakuni Air Station are set to take place after Japan and the U.S. confirm the Osprey’s safety, press reports say. Marine officials say they are ready to start flights as soon as the Japanese approve.

Full flight operations have been scheduled to start this fall at the Marines’ Futenma Air Station in Okinawa.