Dirt particles ingested into the compressor tend to coat all components except which?

Dirt particles ingested into the compressor tend to coat all components except which?

• A. Piston Rings
• B. Accessory Gearbox
• C. Combustion Chamber
• D. Turbine Blades

Answer: (D)

When dirt-laden air is drawn into the compressor, the particles travel with the flow through the engine’s air path. As this dirty air moves, the particles tend to deposit on surfaces that it contacts along the way—such as moving parts and surfaces in the compressor section, seals and rings that the air bypasses or lubricating areas, and surfaces in the combustion chamber where deposits can form. These areas are exposed to the dirty intake air and are more likely to pick up and hold dirt. The turbine blades, however, sit in the exhaust/hot-gas path downstream of the combustion chamber and are not in the direct path of the incoming dirt from the compressor. They’re exposed to different gases and conditions, so they don’t accumulate the same “dirt coating” from the compressor’s intake air as the other components do. This is why the statement points to the turbine blades as the exception.

When dirt-laden air is drawn into the compressor, the particles travel with the flow through the engine’s air path. As this dirty air moves, the particles tend to deposit on surfaces that it contacts along the way—such as moving parts and surfaces in the compressor section, seals and rings that the air bypasses or lubricating areas, and surfaces in the combustion chamber where deposits can form. These areas are exposed to the dirty intake air and are more likely to pick up and hold dirt.

The turbine blades, however, sit in the exhaust/hot-gas path downstream of the combustion chamber and are not in the direct path of the incoming dirt from the compressor. They’re exposed to different gases and conditions, so they don’t accumulate the same “dirt coating” from the compressor’s intake air as the other components do. This is why the statement points to the turbine blades as the exception.