On approach for landing, a C130 E Model aircraft lowers landing gears only. Flaps are already down. While Lowering the landing gears, utility pressure drops to 1375 PSI and low pressure EDP light of both Engines and low pressure light of Utility Suction Boost Pump illuminated. As soon as the Landing Gears were extended completely, system pressure came back to Normal with all conditions within limit. To what component can this occurrence be attributed? Can it be the failure of Utility System Accumulator, Suction Boost Pump or EDP? And if we were to attribute this to Accumulator, is it possible for an Accumulator to suck hydraulic pressure from pressure line to fulfill its pre charge pressure once it is used?