A federal judge has ruled against the family of one of two California-based Marines killed in an Osprey crash in Waimanalo who sued the manufacturers of the tilt-rotor aircraft.

The parents of 21-year-old Lance Cpl. Matthew J. Determan sued Boeing Co., Bell Helicopter Textron and Eaton Aerospace over the May 17, 2015, crash of a MV-22B Osprey at Marine Corps Training Area Bellows.

Lance Cpl. Joshua E. Barron, 24, died the day of the crash. Determan died two days later.

U.S. District Judge Leslie E. Kobayashi decided the lawsuit last week in favor of Boeing, Bell and Eaton. Kobayashi ruled that the manufacturers qualify for the government contractor defense.

The U.S. government and its employees enjoy immunity from liability for performing government functions. The immunity extends to government equipment manufacturers if the government approved reasonably precise specifications for the equipment, the equipment conforms to those specifications and the manufacturers warned the government of the known dangers of using the equipment.

Determan’s parents claimed in their lawsuit that the Osprey did not conform to the U.S. government’s design specifications for operating and hovering in reduced-visibility environments and that the manufacturers failed to include adequate safety measures and warnings. They focused on the Osprey’s air particle separator system for limiting the amount of dust and sand entering its engines.

The Marine Corps’ investigation determined that the aircraft plunged to the ground in a “hard landing” after its left engine stalled due to repeated, sustained hovering in dust or sand clouds. The investigation faulted the pilots for failing to adjust their landing or choose an alternate landing site to avoid creating and landing in dust or sand clouds.