[1] While internal wing structure commonly provides much of the strength via a combination of spars, ribs and stringers, the external skin typically carries a proportion of the loads too.
[4] During January 2017, European aerospace conglomerate Airbus Group announced that they had created the world's first single-piece composite center wingbox, stating that it represented a 20 per cent reduction in the cost of manufacturing by being easier to assemble.
[6] Destructive testing of wing elements has been around since the earliest days of aviation, although the specific techniques employed have become increasingly sophisticated, particularly since the invention of the strain gauge in 1938, which has been in widespread use within the aerospace industry since the Second World War.
[7] Non-destructive testing is also performed not only during the initial certification process but often throughout an individual aircraft's life to safeguard against fatigue failure and inspect potential damage inflicted.
[11][12] During Summer 2019, the United States Air Force was compelled to ground over 100 of its Lockheed Martin C-130 Hercules transport aircraft for inspection and remedial work upon discovering excessive wingbox cracking.