A clipboard left behind during pre-flight checks was sucked into the jet engine of an international passenger plane, Australian safety regulators said Tuesday.
Ground staff put the bundle of paperwork on the engine cowling after loading luggage - but seemingly forgot to pick it up again.
A worker conducting final safety checks spotted the misplaced documents, but assumed they would be retrieved before take-off.
When the engines were started, they swallowed the clipboard, spraying bits of paper all over the tarmac as the aircraft began taxiing into position.
However, no-one told the flight crew until the Sydney-bound plane was in the air, forcing the pilot to return to Auckland.
"The engine was inspected by engineers and paper was found throughout the engine. They also found... a piece of sheared metal," the Australian Transport Safety Bureau (ATSB) said in a report.
Qantas-owned Jetstar, which was operating the October 27 flight last year, has since updated its procedures to include warnings about not placing items in the engine cowling, the ATSB said.
"This incident demonstrates the effect foreign object debris has on aircraft operations," the ATSB said, adding that debris "poses a significant threat to aircraft safety".
"It has the potential to cause aircraft damage during critical phases of flight, costing airlines and airports millions of dollars each year."