Final answer:
The HGU-55 helmet requires modifications for use with Combat Edge to help pilots withstand higher g-forces by integrating additional support equipment such as pressure bladders and communications systems.
Step-by-step explanation:
The HGU-55 helmet must be modified when it is used with Combat Edge to ensure the pilot receives the operational benefits of the system.
Combat Edge is an aircraft life support system designed to help fighter pilots withstand higher g-forces by providing increased oxygen and pressure to their body. Modifications to the HGU-55 can include integrating a visor projection unit, communications equipment, and pressure bladders that increase the safety and effectiveness of the helmet when combined with the Combat Edge system.