Definition
A group of living organisms — including molds, mildews, and yeasts — that grow in damp, dark conditions and can contaminate aircraft fuel, fuel tanks, and other components, causing corrosion, blockages, and degraded fuel quality.
Plain English
Tiny living growths, like mold, that can take hold inside aircraft fuel tanks and on other parts when moisture is present. As they grow, they damage the metal and clog fuel systems.
Context Anchor
Seen during aircraft cleaning, storage inspections, fabric and wood structure inspections, and checks of areas where moisture can collect.
Derivation
From the Latin fungus, meaning 'mushroom.' The word now covers a broad family of organisms beyond mushrooms, including the molds and yeasts that cause aircraft fuel contamination.
Why Pilots Care
Unchecked fungus growth can restrict fuel flow, cause engine stoppage, and lead to expensive corrosion damage requiring tank repairs or replacement.
Intuition Check
Fungus does not only mean a mushroom you can see. In aircraft maintenance, it includes mold or mildew growth on aircraft materials, even when it first looks like a stain or discoloration.
Example Sentence 1
During the fuel tank inspection, the technician found fungus growth at the water drain and treated the tank with a biocide.
Example Sentence 2
Treating the tanks with biocide prevents fungus from growing during long periods of aircraft storage.