The US Air Force (USAF) and US Navy (USN) has grounded their V-22 Osprey tiltrotor aircraft fleets on 6 December, following a crash of a CV-22B operated by the USAF 353rd Special Operations Wing in the waters off Yakushima Island in Japan on 29 November.
“Preliminary investigation information indicates a potential materiel failure caused the mishap, but the underlying cause of the failure is unknown at this time,” said head of US Air Force Special Operations Command (AFSOC) Lieutenant General Tony Bauernfeind in a statement.
“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,” the USN’s Naval Air Systems Command said in a separate statement.
“While the mishap remains under investigation, we are implementing additional risk mitigation controls to ensure the safety of our service members,” added NAVAIR.
AFSOC noted that the CV-22B was deployed from Yokota Air Base in western Tokyo and was carrying out a routine training mission with eight personnel on board. All were declared deceased.
Japan Coast Guard and Japan Self-Defense Force units joined the US military in a combined search for the downed aircraft and survivors, with search teams able to locate the wreckage as well as remains of some crewmembers on 4 December.
The V-22 Osprey has suffered several high-profile mishaps in recent years. A US Marine Corps (USMC) MV-22B carrying 23 crewmembers crashed during a military exercise in Northern Australia in late August, resulting in the loss of its three crew and another three injured.
The type’s unique hybrid design, which is aimed at combining the advantage of vertical take-off and landing and hover capabilities of helicopters with the speed and range of fixed wing aircraft, has been seen as a factor in multiple incidents.
The latest incident prompted yet another protest by Okinawa residents and the grounding of all 14 CV-22B Ospreys operated by the Japan Ground Self-Defense Force.
by Jr Ng