the particle trap that extends behind an elbow in the air flow stream in a turbo - prop engine is delimited at the back by an end plate to which intake housing suspension rods supporting the front of the rotating shaft , are fastened . it is divided by suspension arms which may be drilled to restore the continuity of the annular chamber forming the trap . therefore the intake housing suspension device extends through the trap . this type of trap makes use of the inertia of solid bodies carried by the air drawn in , and which could damage the engine blades , and to collect them .