text: Alclad sheeting has become a widely used material within the aviation industry for the construction of aircraft due to its favourable qualities, such as a high fatigue resistance and its strength. During the first half of the twentieth century, substantial studies were conducted into the corrosion qualities of various lightweight aluminium alloys for aviation purposes. The first aircraft to be constructed from Alclad was the all-metal US Navy airship ZMC-2, which was constructed in 1927 at Naval Air Station Grosse Ile. Prior to this, aluminium had been used on the pioneering zeppelins constructed by Ferdinand Zeppelin.
  Alclad has been most commonly present in certain elements of an aircraft, including the fuselage, structural members, skin, and cowls. The aluminium alloy that Alclad is derived from has become one of the most commonly used of all aluminium-based alloys. While unclad aluminium has also continued to be extensively used on modern aircraft, which has a lower weight than Alclad, it is more prone to corrosion; the alternating use of the two materials is often defined by the specific components or elements that are composed of them. In aviation-grade Alclad, the thickness of the outer cladding layer typically varies between 1% and 15% of the total thickness.