A Qantas jet grounded in Melbourne today because of noise from an air-conditioning fault was the same plane that returned from routine maintenance in Malaysia two months ago with 95 defects.
The Canberra-bound Boeing 737 jet returned to the terminal and passengers were transferred to another plane, finally leaving Melbourne 90 minutes later, just before 1pm (AEST).
A Qantas spokeswoman said QF850 had problems with an air-conditioning duct unit while taxiing towards the runway.
"It was a routine return to the terminal due to an air-conditioning fault," she said.
"Rather than delay passengers further, a replacement aircraft was arranged and the flight took off just before 1pm."
The 737, registered as VH-TJU, is the same aircraft on which Qantas engineers found 95 defects that had been missed during contract maintenance work by Malaysian Airlines in Kuala Lumpur.
News Limited newspapers at the time said the faults included a galley that was so badly installed it was a fire risk and gave a flight attendant an electric shock.
The Qantas spokeswoman confirmed the aircraft in today's incident was the same one.
"As with any maintenance undertaken overseas, it (the work) was carried out with the oversight of Qantas Australian engineers," she said.
The 737 had been back in service for seven weeks after the defects were repaired, she said.
When asked if Qantas' overseas maintenance schedule would be reviewed following today's incident, she said: "It is not relevant, because it was unrelated to that maintenance check."
A maintenance worker, who did not want to be named, said the noise from the plane's undercarriage which led to today's grounding could have been produced by a large flow of air through the faulty air-conditioning.
"The fault caused a lot of air and noise down into the lower side of the aircraft, into the undercarriage," he said.
A passenger said the plane was taxiing to the runway before it was turned around.
"... The engineers were then having a look at what may have been a problem within the air-conditioning," passenger Matthew Smith told ABC Radio.
The incident was the latest in a recent run of setbacks for Australia's national airline.
The spate of problems started last month when an explosion ripped a hole in the fuselage of a Qantas jet en route from Hong Kong to Melbourne, forcing an emergency landing at Manila.
Last week, a domestic flight was forced to return to Adelaide after a wheel bay door failed to close.
A Qantas Boeing 767 flight turned back to make an emergency landing at Sydney airport on August 2 after a hydraulic fluid leak was discovered.
On Monday, a jet was grounded for almost three hours after a technical fault was discovered in a pre-flight inspection at Sydney airport.
Qantas chief executive Geoff Dixon admitted this week that the airline's reputation had been tainted by the incidents and said Qantas had to work hard to retrieve its good name.