Definition
In aircraft fabric covering work, a strip of cloth tape applied over a rib or seam to provide a smooth transition and prevent the underlying structure from showing through or wearing the outer fabric. More broadly in maintenance, a bleeder is any fitting, valve, or porous layer used to release trapped air or fluid from a system, such as a brake bleeder valve used to purge air from hydraulic brake lines, or a bleeder cloth used in composite layup to absorb excess resin during cure.
Plain English
A part or piece of material that lets something escape — usually air, fluid, or excess resin — so a system or surface ends up clean, smooth, and working properly.
Context Anchor
Commonly seen during aircraft brake, hydraulic, and other system servicing.
Derivation
From the everyday sense of 'bleed,' meaning to let something drain or escape slowly. A bleeder is the part that does the bleeding — it lets trapped air, fluid, or resin work its way out.
Why Pilots Care
Air trapped in brake lines causes a spongy pedal and weak braking. Knowing what a bleeder valve is — and that it must be used correctly during servicing — is essential for safe ground handling and landing rollout.
Intuition Check
A bleeder is not a leaking or damaged part just because it lets fluid or air out. It is a service point that is opened on purpose during maintenance and closed again afterward.
Example Sentence 1
The mechanic opened the bleeder valve on the brake caliper to release air from the hydraulic line.
Example Sentence 2
With the bleeder closed and the system pressurized, the brakes felt firm with no sponginess.