400Hz AC & 28.5V DC Load Bank, made by MAK Controls & Systems

The MAK Load Bank is a portable test instrument that verifies the output quality of aircraft ground power equipment before it is put back into service or connected to an aircraft. It exists in two complementary variants — a 400Hz AC load bank and a 28.5V DC load bank — which can be deployed independently or as a pair to fully certify a GPU's AC and DC outputs against published specifications. The AC load bank covers 40 kW to 144 kW at 115/200V 400Hz, applying precisely set resistive loads from 0–100% of rated capacity. The DC load bank tests 28.5V GPU and battery-cart outputs at 300 A or 600 A continuous, and uniquely includes an aircraft-engine-start simulation mode that steps the load through a 2,000A → 1,500A → 600A → 300A sequence to replicate the actual current profile drawn during engine cranking. This validates that a GPU's peak-current capability and voltage recovery match what the aircraft will demand at start. Both units share a touchscreen GUI, portable aluminium enclosures with wheeled trolleys for ramp mobility, and connectivity via USB (5-metre cable included), Ethernet and Wi-Fi. The MAK LBMS data-logging software captures time-stamped load, voltage and current records for inclusion in maintenance records or manufacturer warranty claims. The operating range of -20°C to +55°C and humidity tolerance to 95% non-condensing make the units usable year-round in tropical, desert and cold-weather maintenance environments. Continuous-load endurance is 45 minutes at full rated capacity — sufficient for a complete GPU acceptance or pre-C-check electrical certification run. The load bank fills a gap in many ground-handling GSE fleets where GPU output is accepted on trust rather than measured: a single unit reduces warranty disputes and protects aircraft power buses from under-specification ground power.