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.

A cleaning process leading to fuel hose degradation during refurbishment may have caused a recent Airbus A350 engine fire that triggered dozens of Cathay Pacific flight cancellations this month, the

European regulators have widened the number of Rolls-Royce Trent engines affected by a potential fuel hose defect, in an updated directive issued 19 September following an engine fire on a Cathay Pacific Airbus A350-1000.

The European Union Aviation Safety Agency (EASA) on Thursday gave an update on the inspections it ordered on Rolls-Royce-made engines used in Airbus A-350 aircrafts following a security incident, pointing to issues possibly stemming from a cleaning process.

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.

A350 plane flown by Cathay Pacific (OTCPK:CPCAY) (OTCPK:CPCAF) on Sept. 2 was linked to a possible maintenance issue, European aviation safety authorities said Thursday. The engines were made by Rolls-Royce Holdings (OTCPK:RYCEY) (OTCPK:RYCEF).