7News has revealed documents revealing the vulnerability of some Qantas engines.
Rolls Royce engines powering Qantas' fleet of 747s are said to be twice as likely to fail mid-air, than other airlines, internal documents state.
"I would strongly urge customers to not be too concerned with this report. It is under control by both Rolls Royce and Qantas." Alan Milne from Qantas told 7News.
Qantas pilots say that there are potential dangers, especially if an engine fails during take-off, "We are concerned about it, we've written to the chief pilot expressing our concerns." says Captain Richard Woodward, from the Pilots Association.
7News reports the document warns that until the affected fleet is retired, "it remains susceptible to in-flight shut down events."
Qantas insists shut downs are rare, and pose no risk on a four-engine plane.
The report follows an August 2010 Qantas Boeing 747-400 engine failure near San Francisco, a flight emergency considered an irregular occurence by the airline, but one that terrified the 212 passengers on board who reportedly heard a loud bang followed by vibrations and sparks mid-air 20 minutes post-departure of the American west coast.
Reportedly dumping fuel over the Pacific Ocean as it turned back to San Francisco airport, the pilots on the plane declared an emergency as they returned, landing safely with no one injured.
To reduce stress on their engines, Qantas jumbo pilots are being asked to turn off the air conditioning and reduce thrust on takeoff and landing.
The air safety authority says it is monitoring the issue.