European regulators have pinpointed a potentially flawed cleaning process during maintenance as investigators probe an engine fire that caused a Cathay Pacific Airbus jet carrying 348 people to turn back to base.

Hong Kong aviation investigators say an engine problem that caused Cathay Pacific to ground its entire fleet of Airbus A350 jets for inspection earlier this month could have escalated into “extensive damage.

A Hong Kong aviation investigation revealed Cathay Pacific's Airbus A350 engine failure was due to a ruptured fuel hose. The incident highlighted potential risks of engine fires caused by fuel leaks.