Donaldson Co. announced yesterday that it has acquired Aerospace Filtration Systems (AFS) of St. Louis, Mo. The deal, which was inked on Tuesday, calls for AFS to become a wholly owned subsidiary of the worldwide supplier of filters and support. The marriage isn’t new for the two companies; they were selected as a team last year to supply integral barrier filters (IBF) for the Bell 429 and the recently canceled 417. AFS is displaying the filters at Booth No. 609.