The AW139 IBF system, from Donaldson Aerospace & defence, features low-profile conformal fore and aft fairings with dual filter assemblies mounted on the existing engine doors creating a sealed intake plenum. The AW139 IBF system includes an alternate inlet air bypass system and an emergency bypass capability. A compact cockpit switch allows indication and activation of the bypass system. An integral Filter Maintenance Aid also allows for pre- and post-flight, on-condition inspections to assist in mission planning and visual inspection of filter condition.