ELIMINATION OF ENGINE BLEED AIR CONTAMINATION 550185
Air bled from the compressors of some high compression ratio turbojet engines is contaminated because of internal engine oil leakage into the compressor air. External leakage of oil or other fluids wherein such fluids can leak into the engine air inlet can also cause contamination. There are two positive methods of elimination: (1) a catalytic filter which oxidizes the contaminants to carbon dioxide and water; (2) a separate cabin compressor that compresses free stream ram air for cabin air conditioning and pressurization. The method of extracting air from a location in the engine where the compressor air is least contaminated is considered a marginal solution to the contamination problem on some of the present high compression ratio engines. This method of elimination is worthy of consideration providing a marked improvement is realized in the design of those components of the engine that Contribute to leakage.