AH-64 APACHE EXTERNAL AIR PARTICLE SEPARATOR (EAPS) DESIGN AND PERFORMANCE

The design, fabrication, and testing of an External Air Particle Separator for the AH-64 Apache attack helicopter have been accomplished. The requirements of high sand separation efficiency, foreign object damage (FOD) protection, low installed engine power loss, low engine inlet airflow pressure distortion, low weight, and low maintenance requirements in severe operating conditions offered difficult technical challenges. Data showing design details of existing devices with pressure losses for airflows representative of the T700-GE-701 engine installed in the AH-64, and possible engine inlet air pressure distortion values, were not available in the technical literature. Thus, it was necessary to “start from scratch” to conceive, design, optimize, and qualify a sand and dirt separator employing advanced technology vortex tubes in an assembly that could be retrofitted easily and quickly to the AH-64 aircraft with minimum logistics problems. The details of how these technical challenges were met and many of the resultant characteristics of the separator design are presented in this paper. Given also, along with generalized geometry and size data of the resultant design, are performance data of pressure loss and airflow pressure distortion that were measured in bench and flight tests. Emphasis is placed on generalized data that will assist similar efforts for other aircraft as well as the particular results for the Apache helicopter. Results demonstrated that a practical EAPS with sand separation efficiencies exceeding 90 percent could be produced with power losses less than 3 percent and for helicopters of the size and construction of the AH-64 Apache, an installed system weight of less than 200 pounds.