Internal interchangeable modular avionics platform assemblies and methods for removably mounting and interchanging modular avionics platforms within an aircraft. In some embodiments, modular avionics platform assemblies may include a modular avionics platform configured to support various avionics equipment, suitable for removable mounting within a forward fuselage, and interchangeable with a number of alternate platforms. A platform may include a frame structure, and mounting pins and a connector assembly disposed on the frame structure. The mounting pins may project outwardly from the frame structure to align with and detachably secure to corresponding airframe members of an aircraft when the frame structure is in a mounted position. The connector assembly may be disposed on the frame structure and have a plurality of connectors, including connectors for alternating current, direct current, and data. In some embodiments, the platform may also include an environmental cooling system disposed on the frame structure.