In various embodiments, the present invention provides a means for improving gas turbine engine performance by applying fluid flow control to the inter-turbine duct joining a high-pressure turbine spool and an associated low-pressure turbine spool, allowing the low-pressure turbine spool to have a relatively larger diameter than the high-pressure turbine spool. The foliage is mostly tri-lobed, medium to dark green with limited purple tinting. If arc fault occurs, the arc fault detector generates a trip signal and the trip signal is provided to the arc display part.