Its shares are now down over 5% since the fire in Taiwan on Saturday morning.

The European Union’s aviation safety agency (EASA) said Thursday it will require the inspection of at least some of the Airbus A350s in operation after an engine fire on a Cathay Pacific aircraft.

“EASA is taking precautionary measures to prevent any further similar occurrence,” the agency said. “We will require a one-time fleet inspection, which may be applicable only to a portion of the A350 fleet.”

Hong Kong-based Cathay, one of the largest operators of the A350 jetliner, grounded 48 planes for checks on Monday after a Zurich-bound flight had to return to the city shortly after take-off.

Inspections found defective engine fuel lines requiring replacement on 15 of the A350s powered by Rolls-Royce engines, forcing the cancellation of dozens of flights in Asia.

EASA indicated in a statement an engine fire had been behind the Zurich-bound flight having to turn back.

“An A350-1041 aircraft operated by Cathay Pacific on flight CX383 from Hong Kong to Zurich experienced an in-flight engine fire shortly after take-off,” EASA said, adding the fire was “promptly detected and extinguished.”

The agency said the incident was the subject of a safety investigation led by the Air Accident Investigation Authority of Hong Kong (AAIA) and added it is taking “precautionary measures to prevent any further similar occurrence.”

EASA said the inspections would seek to “identify and remove from service any potentially compromised high pressure fuel hoses” and said the compliance time frame was still being determined and would be detailed later Thursday in an EASA Emergency Airworthiness Directive.

Cathay had indicated Monday that “the component was the first of its type to suffer such failure on any A350 aircraft worldwide”.

The incident prompted other airlines in the region to carry out similar checks on their A350-900 and A350-1000 models, which are powered by Rolls-Royce Trent XWB-84 and XWB-97 engines, respectively.