There is provided a force balancing actuator for mounting a pressure vessel, containing an engine, to aircraft structure. The force balancing actuator includes a cylinder and piston that is mechanically connected between the pressure vessel and aircraft structure. This piston and cylinder adjustably provides force there between in response to variations in differential pressure between the pressurized cabin and ambient pressure. The cylinder and piston thereby relieves excessive load on engine isolators allowing the isolators to absorb engine vibrations.