Definition
In an aircraft disc brake assembly, the stationary plate mounted to the wheel axle or torque tube that supports the brake pucks (lining pads) and provides the reaction surface against which the brake disc is clamped during braking.
Plain English
The fixed metal plate at the back of a disc brake that holds the brake pads and pushes against the spinning brake disc to slow the wheel.
Context Anchor
Seen during aircraft maintenance, especially when inspecting wheel brakes or other assemblies that have parts mounted to a supporting plate.
Derivation
Back from Old English meaning the rear or fixed side, combined with plate from Old French meaning a flat sheet of metal; the name highlights its position as the non-moving rear element of the brake stack.
Why Pilots Care
Proper backplate condition and installation are essential for reliable braking; damage or looseness can cause reduced stopping power or brake failure on landing.
Intuition Check
Do not read backplate as just any plate near the back of something. In maintenance use, it means a supporting plate that other parts are mounted to or held against.
Example Sentence 1
During the brake inspection, the technician checked the backplate for cracks and confirmed the pucks were seated correctly.
Example Sentence 2
The brake caliper bolts directly to the backplate so the pads can press evenly against both sides of the rotating disc.