More cracks found in Airbus A380 wings

An Airbus A380, the world's largest jetliner, takes part in a flying display during the 49th Paris Air Show at the Le Bourget airport near Paris June 26, 2011.

PARIS (Reuters) - Airbus (EAD.PA) insisted on Thursday that Europe's A380 superjumbo is safe to fly after another set of cracks was discovered in the wings of the world's largest jetliner.

It is the second time in as many weeks that hairline cracks have surfaced inside the mammoth double-decker jet, which entered service four years ago, and their discovery is expected to lead to expanded safety checks.

"It is embarrassing, but we will do everything to ensure safety is not compromised," Chief Executive Tom Enders said.

Airbus said the cracks were found on a number of "non-critical" brackets inside the wings of two aircraft, after similar flaws showed up in five aircraft in early January.

It said the cracks did not prevent the A380 flying safely.

"We have a pretty good understanding, but the investigation is ongoing. What we have developed already is a repair solution and this is what we will apply on the various aircraft if and where it is necessary," Enders told CNN television.

Airbus has dismissed calls to ground its superjumbo fleet over the cracks, which first came to light during repairs of a Qantas Airways Ltd (QAN.AX) A380 damaged by an engine blowout shortly after taking off from Singapore in November 2010.

Two aviation industry officials said European safety inspectors would, however, order additional safety inspections.

A spokesman for the European Aviation Safety Agency confirmed it would issue an airworthiness directive on Friday.

EASA and its U.S. counterpart, the Federal Aviation Administration, issue dozens of bulletins weekly from routine updates to emergency directives following a major scare.

The latest cracking problem was discovered in two aircraft during routine two-year inspections, an Airbus spokeswoman said.

She declined to name the operator of the aircraft, but two industry sources, asking not to be identified, said the latest discovery involved aircraft operated by Dubai's Emirates.

Although Emirates did not comment on the latest Airbus disclosure, a spokesperson said the airline was awaiting an update from EASA regarding the cracks found several weeks ago in the wings of five A380 aircraft.

"We continue to closely monitor our A380 fleet," the spokesperson said. "The aircraft remain fully airworthy and pose no risk to flight safety as affirmed by EASA and the aircraft manufacturer, Airbus. The safety of our passengers and crew is our highest priority."

Earlier this month, Singapore Airlines Ltd (SIAL.SI) and Qantas said they found some cracks in A380 wings.

The latest problems were discovered in the same type of part as the earlier set of cracks - an L-shaped bracket that connects the wing's exterior to the internal "rib" structure.

However, the appearance and location of the latest set of cracks were different. Two out of nine aircraft tested were found to have the newer cracks in the centre part of the wing.

MANUFACTURING ERROR

Aviation experts say the presence of tiny cracks is more risky near the root of the wing where loads are at their peak and least risky at the tip where the wing does least work.

Designers say modern aircraft allow loads to be carried by a different part of the structure when one part fails and most cracking is usually captured early without generating publicity.

"I don't think people necessarily need to be worried about cracks because they are caught in advance and repaired," said Snorri Gudmondsson, assistant professor of aerospace engineering at Embry-Riddle Aeronautical University in Daytona Beach, Florida.

"If the rib feet failed, the load would be transferred to other structural parts. These would eventually develop cracks themselves and increase the chances they would be discovered."

In April, U.S. regulators ordered airlines to inspect older Boeing Co (BA.N) 737 aircraft for cracks after a Southwest Airlines Co (LUV.N) jet landed with a fuselage hole.

The A380s in service are much younger and perform fewer take-offs and landings - the most arduous part of any flight - than the Southwest's stricken 737, which was about 15 years old.

Despite being billed as Europe's "21st century flagship," the iconic A380 has already had a bumpy ride due to development problems and the Qantas blowout, and Toulouse-based Airbus is anxious to prevent any further damage to its image.

Officials said the cracks most likely stemmed from a manufacturing process that put too much stress on the brackets, known as rib feet. The parts themselves were not flawed, according to specialist journal Air Transport Intelligence.

The A380 - developed at an estimated cost of 12 billion euros in Britain, France, Germany and Spain and sold at a catalogue price of $390 million - has room on its wings to park 70 cars and a wingspan of 79.8m (261ft 10in).

Its wings are assembled in Broughton, north Wales, and sent by barge, ship and special road convoy to Airbus headquarters in Toulouse, France, where they go into final aircraft assembly.

Airbus announced plans last week to outsource some work on smaller aircraft wings from Broughton to Korean Aerospace Industries Ltd (047810.KS), drawing fire from British unions who said the move gave an unnecessary edge to foreign rivals.

Airbus, the planemaking subsidiary of EADS (EAD.PA), has so far delivered 68 superjumbos, starting with Singapore Airlines which took the first aircraft in December 2007. It was followed by Dubai's Emirates and Australia's Qantas.

Other operators include Air France (AIRF.PA), Germany's Lufthansa AG (LHAG.DE), Korean Air Lines Co Ltd (003490.KS) and China Southern Airlines Co Ltd (600029.SS).

(Additional reporting by Cyril Altmeyer, Harry Suhartono, Dave Cutler, Bill Rigby, David Fogarty. Editing by Dave Zimmerman and Andre Grenon)