A lawsuit has been filed over the death of a Marine killed when an MV-22B Osprey crashed at the Marine Corps Training Area in Waimanalo last May.

Lance Cpl. Matthew Determan, 21, of Ahwatukee, Ariz., died from his injuries. He was a rifleman assigned to 3rd Battalion, 1st Marines.

His parents, Michael and Charlesa Determan, filed a lawsuit in federal court against the companies that designed and built the aircraft.

They allege that The Boeing Company, Bell Helicopter Textron, and Eaton Aerospace failed to include adequate safety measures and warnings. They’re also alleging the aircraft was defective as designed.

Twenty-two people, one Navy Corpsman and 21 Marines, were on board for what was supposed to be a routine training exercise. In addition to Determan, the crash also killed Lance Cpl. Joshua E. Barron, 24, of Spokane, Wash.

An investigation concluded that repeated, sustained flight time, combined with the reduced visibility caused by dust or sand in the air due to rotor wash while attempting to land, caused the left engine to stall, resulting in a loss of power, leading to an unavoidable free fall to the ground.

The sand and dust caused a buildup of material on the turbine blades and vanes, leading to a compressor stall in the left engine, which decreased lift and resulted in the hard landing.

An excerpt from the lawsuit states:

17. As a direct and proximate result of the failure and crash of the defective MV-22 aircraft, Lance Corporal Determan suffered serious injuries and died.

18. At the time of Matthew Determans’ death, the subject MV-22 Osprey aircraft was being used as intended and in a manner reasonably foreseeable to all Defendants.

19. The subject MV-22 Osprey aircraft was defective and unreasonably dangerous. The MV-22 Osprey aircraft was in substantially the same condition at the time of Matthew’s death as it was at the time it was manufactured and delivered to the United States Government.

20. As a direct and proximate consequence of the subject crash, Lance Corporal Determan suffered mental and physical anguish and suffering and he was caused to fear for his life during the final portion of the subject training flight prior to the crash of MV-22 Osprey bureau number 168020.