Definition
A thick, paste-like adhesive material used to fill gaps, voids, or surface irregularities in composite aircraft structures during repair or manufacture. Paste filler typically consists of resin mixed with lightweight bulking agents, and it cures into a solid mass that restores shape and surface continuity but carries far less structural strength than the surrounding laminate.
Plain English
A putty-like substance used to fill in dents, gaps, or holes in composite parts so the surface is smooth again. It hardens when it cures, but it isn't as strong as the original composite material it sits in.
Context Anchor
Seen in discussions of composite aircraft construction, surface finishing, and damage inspection.
Derivation
Paste' refers to the soft, spreadable consistency before it cures. 'Filler' simply means something that fills a space. Together the term describes its job: a spreadable material that fills voids in a composite surface.
Why Pilots Care
Correct use restores both structural strength and smooth airflow; poorly filled areas can create stress concentrations or drag.
Analogy
It is like using wall putty to smooth a small dent before painting. The wall may look flat afterward, but the putty is not the same thing as the wall structure itself.
Intuition Check
Do not read paste filler as glue or as a strength-making repair. In this context, it is mainly used to fill and smooth the surface.
Example Sentence 1
The mechanic used paste filler to smooth out a small surface void in the composite wingtip before applying primer.
Example Sentence 2
The builder used paste filler on the wing root joint to eliminate small gaps before applying the final gel coat.