If a turbine fuel contamination occurs and a borescope inspection is performed, which component should be inspected?

• A. Cylinders
• B. Pistons
• C. Valves
• D. Spark plugs

Answer: (A)

When fuel contamination is suspected, the most informative place to look is the inside of the cylinder. A borescope lets you peer into the cylinder bore without disassembly, so you can directly observe the surfaces that bear the consequences of contaminated fuel. Contaminants can cause varnish, deposits, and abrasive material to accumulate on the cylinder walls and on the piston rings, leading to scoring, wear, and ring-seal problems. Seeing these signs in the cylinder interior provides clear evidence of how the contamination affected the engine’s sealing and combustion chamber, making the cylinders the best component to inspect. While pistons, valves, or spark plugs can reveal related issues, they don’t show the overall condition of the cylinder walls and piston-ring interfaces as readily or as conclusively as inspecting the cylinder itself.