A microchannel heat exchanger (MCHX) system configured to transport heat within a gas turbine engine, the MCHX system comprising: a first MCHX (108, 118, 300) comprising: a first layer (328, 700) having a plurality of electrochemically etched air-passage microchannels (320, 702) configured to convey a first air stream (114, 122, 208, 210, 322) through the first MCHX in a first direction; and a second layer (324, 500) having a plurality of electrochemically etched working fluid microchannels configured to convey a working fluid through the first MCHX in a second direction opposite the first direction; wherein the second layer (324, 500) of the first MCHX (108, 118, 300) further comprises: an internal intake manifold electrochemically etched into the second layer (324, 500), wherein the internal intake manifold is configured to convey the working fluid to the plurality of electrochemically etched working fluid microchannels; and an internal outtake manifold electrochemically etched into the second layer (324, 500), wherein the internal outtake manifold is configured to receive the working fluid from the plurality of electrochemically etched working fluid microchannels; characterized in that the second layer (324, 500) of the first MCHX (108, 118, 300) includes an arrangement of raised pedestals disposed in the internal intake manifold and the internal outtake manifold, respectively, configured to aid the flow of the working fluid; and in that the first MCHX (108, 118, 300) further comprises a sealing layer (326, 600) bonded to the second layer (324, 500) to provide a working/sealing set, wherein the sealing layer (326, 600) is bonded via diffusion bonding or brazing to a raised substrate (502, 504, 506) of the second layer (324, 500). a first MCHX (108, 118, 300) comprising: a first layer (328, 700) having a plurality of electrochemically etched air-passage microchannels (320, 702) configured to convey a first air stream (114, 122, 208, 210, 322) through the first MCHX in a first direction; and a second layer (324, 500) having a plurality of electrochemically etched working fluid microchannels configured to convey a working fluid through the first MCHX in a second direction opposite the first direction; wherein the second layer (324, 500) of the first MCHX (108, 118, 300) further comprises: an internal intake manifold electrochemically etched into the second layer (324, 500), wherein the internal intake manifold is configured to convey the working fluid to the plurality of electrochemically etched working fluid microchannels; and an internal outtake manifold electrochemically etched into the second layer (324, 500), wherein the internal outtake manifold is configured to receive the working fluid from the plurality of electrochemically etched working fluid microchannels; characterized in that a first layer (328, 700) having a plurality of electrochemically etched air-passage microchannels (320, 702) configured to convey a first air stream (114, 122, 208, 210, 322) through the first MCHX in a first direction; and a second layer (324, 500) having a plurality of electrochemically etched working fluid microchannels configured to convey a working fluid through the first MCHX in a second direction opposite the first direction; wherein the second layer (324, 500) of the first MCHX (108, 118, 300) further comprises: an internal intake manifold electrochemically etched into the second layer (324, 500), wherein the internal intake manifold is configured to convey the working fluid to the plurality of electrochemically etched working fluid microchannels; and an internal outtake manifold electrochemically etched into the second layer (324, 500), wherein the internal outtake manifold is configured to receive the working fluid from the plurality of electrochemically etched working fluid microchannels; characterized in that an internal intake manifold electrochemically etched into the second layer (324, 500), wherein the internal intake manifold is configured to convey the working fluid to the plurality of electrochemically etched working fluid microchannels; and an internal outtake manifold electrochemically etched into the second layer (324, 500), wherein the internal outtake manifold is configured to receive the working fluid from the plurality of electrochemically etched working fluid microchannels; characterized in that the second layer (324, 500) of the first MCHX (108, 118, 300) includes an arrangement of raised pedestals disposed in the internal intake manifold and the internal outtake manifold, respectively, configured to aid the flow of the working fluid; and in that the first MCHX (108, 118, 300) further comprises a sealing layer (326, 600) bonded to the second layer (324, 500) to provide a working/sealing set, wherein the sealing layer (326, 600) is bonded via diffusion bonding or brazing to a raised substrate (502, 504, 506) of the second layer (324, 500).