Definition
An aluminum alloy sheet with a thin layer of pure aluminum bonded to one or both surfaces. The pure aluminum coating protects the stronger but more corrosion-prone alloy underneath from oxidation and corrosion.
Plain English
A type of aluminum sheet used on aircraft skins. It has a strong alloy core with a thin layer of pure aluminum on the outside to keep it from corroding.
Context Anchor
Seen in aircraft sheet-metal construction, skin repairs, material selection, and corrosion inspections.
Derivation
A trade name from 'aluminum' + 'clad' (covered or coated). The word 'clad' comes from the Old English meaning 'clothed.' So Alclad literally means 'aluminum-clothed' — strong alloy wearing a protective coat of pure aluminum.
Why Pilots Care
Scratches or improper sanding during sheet metal repair can cut through the thin pure-aluminum layer and expose the alloy beneath, allowing corrosion to start. Recognizing Alclad surfaces helps pilots and technicians spot corrosion damage early during preflight and inspections.
Intuition Check
Alclad is not paint or a coating added later. It is a thin aluminum layer bonded to the metal when the sheet or plate is made.
Example Sentence 1
The technician noted that the corrosion had penetrated the Alclad surface and reached the alloy core, requiring a patch repair.
Example Sentence 2
Alclad sheet was chosen for the fuselage repair because it matches the original material and resists moisture damage.