Case C-308/21: Judgment of the Court (Eighth Chamber) of 7 July 2022 (request for a preliminary ruling from the Tribunal Judicial da Comarca dos Açores — Portugal) — KU, OP, GC v SATA International — Azores Airlines SA (Reference for a preliminary ruling — Air transport — Regulation (EC) No 261/2004 — Compensation and assistance to passengers — Cancellation or long delay of flights — Article 5(3) — Exemption from the obligation to pay compensation — Extraordinary circumstances — Generalised failure of the aircraft refuelling system at the airport)