The discovery of more instances of cracked wing components was expected after Airbus (EAD.PA) said last week it had found the problem and predicted that until it had time to conduct repairs, a consistent pattern would emerge in further tests.

The European planemaker and airlines insist the world's largest airliner is safe to fly, but are keen to move beyond the issue of small cracks in wing brackets that grabbed media attention and triggered compulsory checks last week.

The European Aviation Safety Agency ordered carriers to inspect almost a third of the global fleet of A380s, starting with six jets operated by Singapore Airlines, to check for one of two types of cracks that emerged in the space of weeks.

"We found cracks in all six," the airline's regional public relations manager for Europe, Peter Tomasch, said during a press event at Frankfurt Airport.

"Four we have repaired and they are flying again. The other two will follow in the coming days."

EASA ordered the most urgent checks on aircraft that had carried out at least 1,800 takeoffs and landings; the six Singapore Airlines aircraft fell into this category.

The agency gave airlines six weeks to perform checks on a second category of jets that had between 1,300 and 1,800 takeoffs and landings, and did not order checks on less heavily used aircraft.

BOEING UNLIKELY TO BENEFIT

Analysts say publicity over the cracks is unlikely to benefit Airbus rival Boeing (BA.N) in the short term as airlines base their decisions on whether to buy the $390 million jet on the economics of its anticipated performance over many years.

However, some say the problems for Airbus and parent EADS (EAD.PA) could deepen if the response diverts scarce engineering resources or passengers balk at flying on the jet. So far no airlines operating the A380 have reported any dip in bookings.

In a bulletin known as an airworthiness directive, EASA last week gave Singapore Airlines, Dubai's Emirates and Air France (AIRF.PA) six weeks to examine a further 14 aircraft.

In total, 68 superjumbos are in operation and a total of 253 have been sold.

Airbus says the cracks were discovered long before they posed a potential safety hazard, but it faces a bill for the checks and repairs which are being carried out at its expense.

"The inspection and repairs are well under way and continuing, in line with the airworthiness directive," a spokeswoman said.

"Airbus is supplying repair kits as well as providing technical and logistical support to our customers".

CRACKS BLAMED ON THREE ERRORS

Cracks on what Airbus describes as a handful of the 2,000 L-shaped brackets fixing exterior panels to the ribcage of each 9,100-square-foot wing first surfaced during repairs to a Qantas A380 that was damaged when an engine exploded in November 2010.

Those initial cracks were seen as a minor glitch in the aircraft's metallic frame, but regulators decided to act when their discovery led engineers to a second and potentially more significant type of crack on the same type of bracket.

Airbus said last week that having understood the problem, it expected most of the aircraft being tested would show similar evidence of cracks and that it had found a simple repair.

It blamed the cracks on three errors: designers' choice of aluminium alloy for some of the "rib feet" brackets, the use of a type of bolt that strained the metal and a way of closing tiny gaps that put too much stress on a handful of parts.

Besides the 24 hours required to empty fuel tanks and carry out visual inspections inside the UK-built wings, the largest ever made for a jetliner, no A380s have been grounded.

However, if unrepaired, the cracks could curtail the maximum service life allowed by regulators. After immediate repairs, Airbus plans to change the type of metal used to build the part.

PILOT REASSURANCE

Singapore Airlines' chief pilot for the A380, Captain Robert Ting, flew to Germany on Sunday in one of the six aircraft that had to be fixed as a result of mandatory inspections so far and sought to reassure future passengers over the aircraft's safety.

"I slept very well," he said, referring to his peace of mind during a rest period while a second crew flew the aircraft.

"We have very competent authorities, and a very competent Airbus," he told reporters in Frankfurt.

Ting piloted the first commercial A380 flight in 2007.

(Reporting by Maria Sheahan, Tim Hepher; Editing by Phil Berlowitz)

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