Abstract: A modular equipment testing apparatus is suitable for use in severe environments. The testing apparatus comprises a base computing unit, an interchangeable test instrument board, and an interchangeable equipment interface pod. The base computing unit and the interchangeable test instrument board are sealed within a computing case. A bottom panel of the computing case is formed of a heat conducting material and acts as a heat sink for removing heat from inside the computing case. The computing case and the equipment interface pod interface to form a hermetically sealed case, which can withstand a drop of 1 meter to a solid surface and immersion to a depth of 0.5 meters in water without damage to components located within the sealed case.