Definition
A chemical compound, often a thin protective coating or treatment, used to separate two materials and prevent unwanted reactions between them — most commonly applied to keep dissimilar metals from corroding when in contact, or to protect a surface from chemical attack.
Plain English
Something placed between two things to keep them from reacting badly with each other. In aviation maintenance, it's usually a coating or layer that stops corrosion or chemical damage where two materials meet.
Context Anchor
Seen in aircraft maintenance descriptions, especially around mounts, stops, landing gear parts, controls, and other areas where parts may move, shake, or contact each other.
Derivation
From the verb 'buff,' meaning to soften or absorb a blow. A buffer historically meant something that cushioned an impact. In chemistry and materials work, the same idea carries over: a buffer absorbs or blocks a reaction that would otherwise occur between two substances.
Why Pilots Care
A worn or failed buffer allows excessive loads to reach the airframe, risking structural damage and hard landings that affect safety and comfort.
Analogy
A buffer works like a rubber bumper on a door: it does not stop the door from moving, but it softens the contact so the door and wall are not damaged.
Intuition Check
Do not read “buffer” as just extra space or a waiting area. In aircraft use, it usually means something that physically softens shock, vibration, or contact between parts.
Example Sentence 1
A zinc chromate buffer was applied between the steel bolt and the aluminum skin to prevent galvanic corrosion.
Example Sentence 2
Proper buffer action keeps the gear from transmitting heavy shocks to the fuselage during touchdown.