Definition
A stationary, non-rotating disc in a multiple-disc brake assembly that sits at the back of the brake stack and provides the fixed reaction surface against which the rotating discs and pressure plate clamp when the brake is applied.
Plain English
The fixed metal plate at the rear of an aircraft brake that the spinning discs press against when you brake. It doesn't move — it's the solid backstop that lets the brake squeeze and slow the wheel.
Context Anchor
Seen in aircraft maintenance descriptions, brake inspections, and wheel-and-brake assembly procedures.
Derivation
From 'back' (rear) plus 'plate' (a flat, rigid piece of metal). The name simply describes its position and shape — a flat plate at the back of the brake stack.
Why Pilots Care
A cracked, bent, or loose backplate can let brake parts shift out of position, which can cause rubbing, uneven braking, or reduced brake effectiveness during taxi, landing rollout, or parking.
Intuition Check
Do not read backplate as just any plate located at the back of something. In a brake assembly, it is a specific fixed support plate that holds and aligns brake hardware.
Example Sentence 1
During the brake overhaul, the technician inspected the backplate for heat damage and uneven wear before reassembling the disc stack.
Example Sentence 2
A cracked backplate was replaced during the annual inspection to restore full brake capacity.