EASA orders inspection of A380 for cracks in wing rib feet

January 20, 2012

The European Aviation Safety Agency (EASA) issued an Airworthiness Directive (AD), ordering inspection of certain Airbus A380 aircraft for the possible presence of cracks in the wing rib feet.

The AD states:

Following an unscheduled internal inspection of an A380 wing, some rib feet have been found with cracks originating from the rib to skin panel attachment holes (Type 1 cracks according to Airbus All Operator Telex (AOT) terminology).

Further to this finding, inspections were carried out on a number of other aeroplanes where further cracks have been found. During one of those inspections, a new form of rib foot cracking originating from the forward and aft edges of the vertical web of the rib feet has been identified (Type 2 cracks according to Airbus AOT terminology). The new form of cracking is more significant than the original rib foot hole cracking. It has been determined that the Type 2 cracks may develop on other aeroplanes after a period of time in service.

This condition, if not detected and corrected, could potentially affect the structural integrity of the aeroplane.

For the reasons described above, this AD requires a Detailed Visual Inspection (DVI) of certain wing rib feet. This AD also requires reporting the inspection results to Airbus.

This AD is considered to be an interim action to immediately address this condition. As a result of the on-going investigation, further mandatory actions might be considered.

The cracks were discovered by Airbus engineers while performing repair work to a Qantas A380 that had suffered an uncontained engine failure near Singapore’s Changi Airport. Singapore Airlines also discovered some cracks in on the L-shaped feet of the wing ribs. The feet attach the rib, a vertical fixture, to the cover of the wing.

On January 9th a spokesman for the Australian Licensed Aircraft Engineers Association demanded that all A380 aircraft should be grounded for inspections. Airbus reported that all planes were safe to fly and that the cracks did not pose a safety threat.

More information:

Report: fatigue cracking caused gear failure of Swedish DHC-6 Twin Otter

June 21, 2010

A de Havilland Canada DHC-6 Twin Otter sustained substantial damage in a landing gear failure in Sweden in June 2009. The Swedish accident investigators concluded that the gear fractured as the result of a fatigue crack.

The pilot intended to take off with 21 parachutists on board the aircraft. He did not notice anything abnormal, neither during the preparations for take-off nor during the initial taxiing.
After taxiing for a few minutes at low speed, suddenly the right main landing gear broke, whereupon the aircraft tipped over to the right and the right wing struck the ground. The aircraft then slowed down, turned somewhat to the right, and stopped. No person onboard was injured.
The technical examination of the aircraft has shown that the right main landing gear fractured as the result of a fatigue crack. The crack consisted of several smaller fatigue cracks that had grown and joined. The cracks had initiated in an external welded joint and developed over an extended period of time without being detected.
The aircraft type has been exposed to landing gear fracture before as the result of fatigue cracks in the actual area. Current maintenance system prescribes NDT inspection of the landing gear within intervals of 12,000 flying hours or five years, whichever comes first.

The Swedish Accident Investigation Board recommends that EASA and the Swedish Transport Agency, in conjunction with the manufacturer, consider the need for supplementing the present maintenance system in respect of crack formation in the landing gear.

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