Precooler for an aircraft engine with a contamination free reverse flow bleed port

A precooler (20) for an aircraft engine system includes a precooler core (38) and a precooler inlet (28) to direct a compressor bleed flow (18) into the precooler core (38) to cool the compressor bleed flow (18). The precooler (20) further includes a precooler outlet (30) to direct the compressor bleed flow (18) from the precooler (20) to a selected component of the aircraft engine system and a precooler bleed port (42) through which a portion of the compressor bleed flow (18) is diverted to a secondary component of the aircraft engine system. The precooler bleed port (42) is oriented such that flow entering the precooler bleed port (42) must substantially reverse direction from a direction of the compressor bleed flow (18) through the precooler (20).