TOULOUSE, FRANCE — An issue referred to as hydrogen assisted cracking, or hydrogen embrittlement, has been recognized as the cause of quickened crack development in particular wing spars of Airbus A380s that have been stored for long durations.

"The primary factor is temperature, followed by moisture," said Pierre-Henri Brousse, who heads the A380 program, in an interview with Aviation Week. He explained that when planes are grounded and subjected to extreme weather conditions, hydrogen diffuses into the materials, causing the aluminum alloy to become brittle. This then facilitates the propagation of cracks.

These discoveries led to the issuance of a May 11 airworthiness directive (AD) by the European Union Aviation Safety Agency (EASA). The AD introduced the idea of "factored time on ground" (FTOG) and mandated inspections, possibly even repairs, based on aircraft age and a maximum takeoff weight (MTOW) limit of 510 tons.

The areas affected are the top and bottom flanges of the outer rear spar (ORS) between ribs 33 and 49. Previous ADs also gave directions for other parts where defects were detected.

As early as 2019, EASA and Airbus decided that inspections must occur 15 years after the date of wing box assembly. Following these discoveries, the maintenance limit was advanced twice.

But this remained insufficient. According to Brousse, some aircraft younger than the limit defined by the regulator were inspected and had findings. Airbus then carried out a thorough analysis to comprehend why even 10-year-old planes were developing cracks.

Significantly, the discoveries will not dramatically alter Airbus' recommendations for storing the A380 or any other model. The aluminum alloy of the affected spars is not used in any other Airbus aircraft and is replaced with a different material during repairs. Brousse said they have no concerns about other components.

Airbus has not revealed which airlines are most impacted by the defects. However, Emirates disclosed in November 2022 that it is addressing the issue. The carrier had stored many of its A380s at the Dubai World Central airport during the COVID-19 pandemic, where they were subjected to high temperatures and humidity during summer.

Currently, 135 A380s are in active service, with 87 operated by Emirates. Most current A380 operators are bringing more aircraft back from storage due to the rapid recovery of long-haul route demand.

According to Airbus, wing inspections take approximately one week. Affected parts can be repaired or replaced. Securing enough maintenance, repair, and operations (MRO) capacity for the repairs is an ongoing challenge, Brousse noted. However, he deemed the situation manageable and Airbus is seeking more MRO providers globally that have the necessary A380 capability and available capacity.