Abstract: A ram air filter for light aircraft comprising a parallelepiped housing and a replaceable filter element is disclosed. The housing comprises a base element and a cover element, which are injection molded of high impact plastic and are connected together in a snap-lock manner. The parallel faces of the base and cover elements include a plurality of ribs that define aligned apertures through which incoming air enters and leaves the housing. The ribs are formed such that they present a minimal amount of surface area to the incoming air stream during flight. A plurality of 90.degree. locking studs attach the housing to the air intake channel of the aircraft's carburetor. The replaceable filter element is also parallelepiped in form and lies in the space defined by the housing so as to filter the air flowing through the aligned apertures. The replaceable filter element is formed of a compressible foam, preferably having a porosity grade lying in the range of 20-50 pores per linear inch.