Installation of Advanced Technology Aircraft Company engine barrier filter in accordance with Advanced Technology Aircraft Company Master Drawing List No. 234, Revision C, dated August 17, 1992, or later FAA approved revisions. This STC is issued for use in the restricted category only, and the rotorcraft must be operated accordingly with the ATAC engine barrier filter installed. View PDF on drs.faa.gov ↗

The STC PDF is authoritative: installation instructions, ICA requirements and limitations.