The American military announced that it has grounded its entire fleet of after a fatal crash off the coast of Japan. A preliminary investigation showed an equipment failure likely caused the crash that killed eight Air Force Special Operations Command service members, At least 475 tilt-rotor VTOL aircraft are in service across the United States Air Force, Marine Corps and Navy.

Last week, an Air Force CV-22B Osprey crashed during a routine training mission near Yakushima Island, roughly 300 miles north of Okinawa. All eight airmen aboard were officially declared dead after the remains of six were located via search and rescue operations. The incident restarted safety concerns about the Osprey during its development and time in service after being introduced in 2007.

Air Force Special Operations Command has grounded the aircraft to eliminate the chance of another crash happening during its investigation. Lt. Gen. Tony Bauernfeind, AFSOC Commander,

“Preliminary investigation information indicates a potential materiel failure caused the mishap, but the underlying cause of the failure is unknown at this time. The standdown will provide time and space for a thorough investigation to determine causal factors and recommendations to ensure the Air Force CV-22 fleet returns to flight operations.”

has now been involved in four fatal crashes over the last two years, killing 20 people. Four service members were killed in a crash during a NATO training exercise in northern Norway In March 2022. Five Marines were killed in a crash during a training mission in California in June 2022. Three more Marines were killed in a crash off the coast of Northern Australia in August this year.

It’s not clear how long the V-22 Osprey will remain grounded. found that a clutch failure caused the June 2022 crash. The failure caused a complete loss of power on the right-hand proprotor. The Osprey has had a clutch problem since it entered service, and no improvement implemented has eliminated this critical issue.