A bird and a bolt of lighting have struck two separate Qantas planes and caused more problems for the Australian airline.
Qantas spokesman Tom Woodward said a Boeing 747 carrying 171 passengers bound for Sydney turned back to Johannesburg in South Africa after a bird slammed into one of the jumbo jet's four engines shortly after take-off. It landed safely.
Separately, a Boeing 717 sustained minor damage to its fuselage when it was struck by lightning during a domestic flight between the Outback cities of Alice Springs and Darwin.
Mr Woodward said the plane continued safely to its destination of Darwin.
Four Qantas jumbos have turned back because of various problems since a November 4 engine blow-out on a Qantas Airbus A380 near Singapore triggered a global safety review of the plane.
Extra attention has focused on Qantas - which has a reputation as one of the world's safest airlines - since the November 4 A380 incident, when one of the plane's four Rolls-Royce Trent 900 engines disintegrated in flight and sent shrapnel ripping through the wing.
Aviation officials have identified an oil leak near a turbine as the flaw which caused a fire and the engine failure, and Qantas's six A380s - the world's largest passenger plane - remain grounded while the airline carries out checks and repairs. The other carriers using Trent 900s on their A380s, Singapore Airlines and Lufthansa, have returned their planes to service.
Four Qantas flights have turned back to port since the A380 incident because of various faults and problems. The airline says none of them were as serious as the superjumbo problem, and the turnarounds were in line with Qantas's routine safety procedures.
The day after the A380 problem, a Qantas Boeing 747 bound for Sydney turned around and landed safely in Singapore after an engine caught fire minutes after take-off.
Last Friday, a Boeing 767 turned back on a domestic flight in Australia after pilots detected abnormal vibrations in an engines. And on Monday, the flight crew on board a Qantas Boeing 747 bound for Argentina donned oxygen masks and returned to Sydney after an electrical fault sent smoke into the cockpit.