European safety authorities are set to order airlines to carry out checks on almost a third of the current Airbus A380 fleet after the discovery of wing cracks on the world's largest jetliner, aviation sources said on Friday.
The one-off inspections are likely to affect superjumbo aircraft operated by Singapore Airlines, Dubai's Emirates and Air France, the sources said, asking not to be identified because the ruling has not yet been released.
The two-speed recommendation is expected to call for checks within days on a handful of the most heavily used aircraft.
These have been subjected to at least 1,800 take-offs and landings, the part of the flight where the airframe endures most stress.
A second category of around 20 aircraft that have carried out 1,300 to 1,799 flight cycles must be checked within six weeks. A flight cycle is one take-off and landing.
No aircraft will be grounded pending the checks, which involve taking an aircraft out of service for about 24 hours.
European safety agency EASA said it would issue its recommendations later on Friday.
Airbus declined to comment ahead of the EASA publication but said on Thursday it had found a solution to tiny cracks spotted in two sets of inspections and pledged to put safety first.
The second set of cracks on the double-decker aircraft's UK-made wings came two weeks after the problem first came to light during $130 million of repairs to a Qantas A380 at the centre of an engine blowout and major safety scare in November 2010.
The A380 entered service in December 2007 with Singapore Airlines, followed by Emirates and Australia's Qantas.
Other operators include Air France, Korean Air,
China Southern and Germany's Lufthansa.
A total of 68 of the 525-seat aircraft are in service.
The oldest aircraft are not necessarily those facing the fastest inspections. Qantas, for example, uses the A380 on long Pacific routes with proportionately fewer take-offs and landings than those used on shorter runs.
Air France placed the giant A380 at first on the short hop between London and Paris in order to perfect cabin operations.
An Air France spokeswoman declined to comment ahead of the publication of EASA's airworthiness directive.
Emirates also declined to comment.
In a separate incident, Air France said an A380 bound for Montreal turned back over the Atlantic and returned to Paris with 448 people on board late on Thursday after a video screen overheated. A spokeswoman denied a report of smoke in the cabin.