It has emerged that Qantas was forced to inspect a large portion of its fleet and notify other airlines after an incident last year when engineers at Melbourne mistakenly pumped nitrogen into the emergency oxygen tanks of one of its Boeing 747-300s.

Australia's Civil Aviation Safety Authority says Qantas engineers mistook a nitrogen cart for an oxygen cart and pumped nitrogen into the 747's emergency oxygen tanks.

Nitrogen is used to fill aircraft tyres and, if inhaled, it can quickly cause a person to black out. CASA says that, fortunately, one of Qantas' other engineering personnel noticed the mistake before the aircraft departed.

Following the incident, which occurred on 25 September 2007 but has just come to light, the airline inspected 51 of its aircraft, says CASA. All 51 aircraft could potentially have been pumped with nitrogen, but once inspected were found to have no irregularities, it adds. Qantas also notified foreign carriers that use its ground engineering services at Melbourne airport, says CASA.

It declines to disclose the name of the airline customers, but Air New Zealand has said publicly that Qantas notified it and ANZ engineers have had to inspect some of its aircraft as a precaution.

The Australian Transportation Safety Bureau says it is aware of the matter, but adds: "We are not investigating this occurrence." However, Qantas executive general manager David Cox says the ATSB put forward some recommendations that Qantas has since implemented. He says the airline has introduced some additional procedures to ensure the mistake is not repeated.

Cox stresses that only a small amount of nitrogen was pumped into the 747-300 and the error was quickly detected before the aircraft departed. "The entire tank was purged and then refilled with oxygen," he says, adding that the airline inspected its entire 747 and Airbus A330 fleets and no other aircraft were found to be contaminated.

Source: Flight International