The European Aviation Safety Agency (EASA) issued an airworthiness directive requiring inspections and possibly modifications to the Airbus A380, stating that cracks discovered during fatigue testing could “reduce the structural integrity of the wing.”
The safety agency said cracks, initiated by “high local stress,” were detected on cruciform fittings on fuselage frame 56 during full-scale fatigue testing. The AD, which is effective on November 18, requires that operators perform a one-time inspection within 4,200 flight cycles or 30,900 flight hours after an aircraft’s first flight, whichever occurs first. If cracks are found, various Airbus service bulletins apply, depending on the size of the crack. Airbus says it does not expect operators to find any cracks exceeding a few millimeters. Some modifications should be carried out even in the absence of crack.
An Airbus spokesman emphasized that a cruciform fitting is not a load-bearing part. “No immediate work is needed; this is not an emergency AD,” he told AIN. The inspections and modifications are not time-consuming and ensure the full life of the aircraft, he said. “We are doing continuous testing, even after entry into service,” he added, which led to the prediction of potential problems.
Between 2004 and early 2007, as part of its development program, the manufacturer subjected the A380 to 26 months of fatigue testing and 47,500 flight cycles, or 2.5 times what an A380 would perform in 25 years of operations.
The cracking issue is the latest in a series of structural problems that have occurred during the A380’s development and service life. In August last year the EASA reported “crack initiations” on the wing inboard leading-edge droop nose gooseneck brackets and intercostals. Concerned about the possibility of in-flight detachment of a droop nose panel, the agency required inspections and, if needed, replacement of the parts.
Earlier in 2012, the EASA mandated inspections for cracks in wing-rib feet for the entire A380 fleet. This action caused Airbus to arrange both retrofits and production modifications. The manufacturer estimated the total cost of modifications to be €260 million ($340 million).
In 2006, during static tests, a wing failed before the ultimate load was reached. The trial involved a load equal to 1.5 the maximum load expected to be encountered in normal service. The wing failed within 3 percent of the 1.5 load target, Airbus said at the time, pointing out that the wing had previously undergone other severe testing. It assured that wings already manufactured for production aircraft were stronger than the one used for static tests.