The engine defect in the Airbus A350 plane that led to the cancellation of dozens of Cathay Pacific flights in early September could have escalated into “extensive damage”, according to a Hong Kong probe released Thursday. Hong Kong-based Cathay Pacific briefly grounded its fleet of A350s for inspections and repairs after a Zurich-bound plane was forced to turn back to Hong Kong on September 2. The inspection found that components on 15 of the 48-plane fleet of A350s, powered by engines from the British manufacturer Rolls-Royce, had to be replaced. On Thursday, investigators in the city said a post-flight examination found a “discernible hole in the (fuel) hose”, “black soot observed on the aft section of the core engine, indicating signs of a fire” as well as burn marks.