The families of two people who died in a helicopter crash that also killed the owner of Leicester City are suing a firm that made parts for the aircraft.
Pilots and partners Eric Swaffer and Izabela Lechowicz died along with Vichai Srivaddhanaprabha and two others at the King Power Stadium in 2018.
Papers filed with the District Court of Massachusetts allege failures by US company Raytheon.
An interim crash report pointed to a failure in the tail rotor system.
Mr Swaffer and Ms Lechowicz, along with Mr Vichai and employees Kaveporn Punpare and Nusara Suknamai all died when the chairman's helicopter crashed and exploded moments after taking off at the stadium on 27 October.