Definition
Mesh or screen filtering devices installed in an aircraft's fuel and oil systems to trap dirt, water, sediment, and other contaminants before they reach the engine. They are removable for periodic cleaning or replacement and are listed by the FAA among items a certificated pilot may service as preventive maintenance on aircraft they own or operate (excluding those flown under Part 121, 129, or 135 operations).
Plain English
Small filters in the fuel and oil lines that catch grit and water before it gets into the engine. Pilots are allowed to clean or replace them as routine upkeep.
Context Anchor
Seen during aircraft inspection and preventive maintenance, especially when checking, cleaning, or replacing items in the fuel and oil systems.
Derivation
A 'strainer' comes from the same root as 'strain' — to press or filter through a mesh. The word has been used for centuries for any device that separates solids from liquids. In aviation it carries the same plain meaning: something that strains the fuel or oil before the engine sees it.
Why Pilots Care
Blocked or dirty strainers can starve the engine of fuel or oil, leading to power loss or failure.
Analogy
A kitchen sink strainer lets water drain while catching food scraps. An aircraft strainer does the same basic job for fuel or oil, but with much higher safety consequences.
Intuition Check
Do not think of a strainer as a fuel or oil container. In this context, it is a screen or filter that fluid passes through to remove unwanted material.
Example Sentence 1
Before the first flight of the season, the owner cleaned the fuel and oil strainers and logged the work as preventive maintenance.
Example Sentence 2
The mechanic replaced the oil strainer after finding metal particles caught in the mesh during an oil change.