Qantas, Australia’s national airline, grounded its Airbus A380 fleet indefinitely after part of a plane’s engine cover fell off in mid-flight Thursday.

The airline said flights of the twin-deck planes — the world’s largest airliners — will remain suspended until an investigation into Thursday’s incident is complete.

“As long as it takes,” said airline CEO Alan Joyce, when a reporter asked how long the suspension will last. “We are being very cautious until we know exactly what caused this.”

A Qantas airliner had one of its four engines shut down six minutes after takeoff Thursday from Singapore’s Changi Airport, Joyce said. The plane — with 440 passengers and 26 crew members — was headed to Sydney, Australia, but it returned to Changi.

While in the air above the western Indonesian island of Batam, part of the engine’s covering, or cowling, tore off and fell.

Local television stations in Indonesia showed debris parts with red-white markings. Pictures of the Airbus A380 after it landed showed the cowling torn off in the back half.

Trifuadi, a security officer at an engineering firm in Batam, said he heard a loud explosion and saw smoke coming out of the engine of a plane flying overhead.
Shortly afterward, debris fell from the plane to the ground, said Trifuadi, who like many Indonesians go by one name.

The flight — QF32 — landed in Singapore safely, without injury to passenger or crew.

(Source: CNN)