The design of the power control and accessory systems of the GE4 engine for the United States supersonic transport strongly responds to airlines needs for ease in maintenance and overhaul. Next to safety, the first objective in design is long life and dependable, trouble-free operation. However, in commercial use the service periods will always continue to extend out to the maximum capability of the design, and maintainability for ease in component replacement will still be required as condition indicates. Moreover, designs favoring maintainability will receive better maintenance and thereby yield longer service before replacement. In this paper the integrated power control and the accessory systems of the GE4 are presented. The design reflects the efforts to understand the user's point of view. It shows physical aspects of the configuration including routine maintenance, and the replacement, teardown, overhaul, and calibration of a typical component of each type, i.e., fuel control, pneumatic, lube, and hydraulic. Development buildup and test utilizing the capsule or package concept for the entire configuration of the gearbox, piping, and accessories assembly enforce the accelerated growth toward maintenance-maturity of the design. Bench flow-test facilities, ancillary checkout and leak-test equipment, and a typical traveling-tester for engineering diagnosis of control system symptoms during development are shown.