Which contamination sources during overhaul and how are they controlled?

• A. Water ingestion only
• B. Magnetic filings only
• C. Metal shavings, oil, and dirt; controlled with cleanroom practices, filtration, lint-free materials, and thorough cleaning
• D. Only dust from packaging

Answer: (C)

Contamination control in overhaul centers on preventing debris that can damage engine parts and clog essential paths: metal shavings from machining, oil residues that can carry fine particles, and dirt carried by handling and the work environment. These contaminants pose real risks to bearings, seals, and tight tolerances, so the approach is to keep the work area, tools, and components as pristine as possible.

Using cleanroom-like practices helps minimize particle generation and introduction. That includes restricted access, proper gowning, clean benches, and organized workflow to prevent cross-contamination. Filtration removes particulates from the air and from fluids, helping keep ventilation and lubrication paths cleaner. Lint-free materials—wipes, cloths, coverings—prevent shedding fibers that could lodge in tiny clearances. Thorough cleaning, including degreasing, washing, rinsing, and careful inspection, ensures residues and particulates are removed before assembly or installation.

Other sources mentioned, like only water ingestion, only magnetic filings, or only dust from packaging, are incomplete because they don’t address the broader set of contaminants and the comprehensive controls needed to prevent them.