Two engines - on aircraft in Sydney and Los Angeles - have been taken off for closer inspection as a result of the eight-hour tests Rolls-Royce recommended, Fairfax newspapers say.
It now seems increasingly unlikely that the grounding of the fleet will be limited to the 48 hours outlined by chief executive Alan Joyce on Friday, Fairfax says.
Thousands of people will experience delays as the airline shuffles its fleet to cover the grounded A380s, spokesman Simon Rushton said.
The airline has one A380 in Singapore under investigation, one in Germany for servicing, one in Sydney and three in Los Angeles undergoing checks after the midair engine explosion on QF32 on Thursday.
Qantas will not say what the nature of the issues is, or whether the three engines are being examined for the same matters.
"It's things that might apply to different components. I can't be more specific than that," Mr Rushton said.
He said reports that the inspection of the Sydney plane's engines centred on the intermediate-pressure turbine bearings were incorrect.
The engine explosion on QF32 from Singapore to Sydney on Thursday, the overheated engine on QF6 on Friday from Singapore and the cockpit warning of a hydraulic problem on QF29 from Hong Kong to London on the same day has overshadowed what should have been a weekend of celebration for Qantas's 90th anniversary.
