Battery Start Units
Hand-portable battery start units are the most common form of aircraft ground power equipment. These self-contained packs deliver a high-current burst to turn over turbine and piston engines without requiring an external mains connection. They are used on ramps, flight lines, remote airstrips, and anywhere a mains-powered GPU is impractical.
Modern units are available in two battery chemistries: traditional sealed lead-acid and lithium iron phosphate (LiFePO4). Lithium packs offer up to 42% weight savings and roughly double the cycle life, but carry a higher upfront cost. The choice between them depends on how frequently the unit will be used, portability requirements, and whether cold-weather starting is a factor.
Selection depends on matching peak starting amperage to the aircraft's starter motor requirements. Undersizing results in hot starts and excessive starter wear. Oversizing adds unnecessary weight and cost. Our GPU Sizing Guide covers the calculation methodology in detail.
Comparing chemistries? See our detailed Lead Acid vs Lithium Start Pack Analysis covering weight, cycle life, cold-weather performance, and 5-year total cost of ownership.
Continuous DC Power Supplies
Continuous power supplies deliver stable, regulated 28V DC from a mains connection for extended periods. Unlike battery start packs, these units are not designed for the high-current transient of engine starting — they provide clean, ongoing power for avionics testing, software updates, crew training, weapons systems checks, and other maintenance operations that require the aircraft's electrical bus to be powered without running the engine.
Two primary product families exist in this category. The RBSC range is engineered for military and high-use MRO environments requiring ruggedized enclosures, precise voltage regulation (typically ±0.5%), and the ability to operate continuously in demanding conditions. The RBPS range provides a more cost-effective solution for general aviation and light commercial applications where duty cycle requirements are less severe.
Transformer Rectifier Units
Transformer rectifier units convert AC mains power to high-current DC output suitable for both engine starting and extended maintenance operations. The largest units in this category can deliver 600A continuous and over 2,000A peak at 28V DC, making them suitable for the most demanding applications in commercial MRO hangars and military flight lines.
TRUs are typically fixed installations — they are not portable in the way battery start packs are. Their primary advantage is the ability to deliver sustained high-current output without the duty cycle limitations inherent to battery-based systems. For facilities that service multiple aircraft types requiring frequent starts and extended maintenance power, a properly specified TRU eliminates the logistical overhead of managing multiple battery packs.
Planning a fixed-installation power system? Our Transformer Rectifier Unit Guide covers specification methodology, facility planning, and manufacturer comparisons.
400Hz Frequency Converters
Commercial and military aircraft operate their onboard electrical systems at 400Hz — a frequency chosen because it allows smaller, lighter transformers and motors compared to 50/60Hz equivalents. This design decision, which saves significant weight in flight, creates a ground-side requirement: converting standard mains power to the 115V or 200V, 400Hz AC that aircraft systems expect.
Ground-based frequency converters handle this conversion. They range from small solid-state units rated at 5 KVA for general aviation maintenance to large fixed installations rated at 90 KVA or more for commercial airport gate positions. The industry is moving decisively toward solid-state designs, which offer lower maintenance costs, reduced noise, and zero direct emissions — a factor of increasing importance as airports face sustainability mandates.
Aviation Tools & FOD Systems
Foreign Object Damage prevention is among the most critical safety concerns in aircraft maintenance. A single misplaced tool left inside an aircraft structure can cause catastrophic failure. Modern tool control systems address this risk through shadow boards, RFID tracking, barcode scanning, and access-controlled cabinets that enforce a check-in/check-out discipline for every item.
Complete aviation tool kits are available pre-configured for specific maintenance tasks and aircraft types. These range from basic hand tool sets (wrenches, pliers, screwdrivers, torque tools) to specialized avionics test kits and engine maintenance packages. Manufacturers like Red Box Tools and Bahco develop aviation-specific tool lines in conjunction with maintenance technicians at organizations including Lufthansa Technik, ensuring that each kit reflects actual workflow requirements rather than generic tool assortments.
Tool categories covered
Hand tools and general maintenance sets, calibrated torque tools, aviation-rated power tools, avionics test and measurement equipment, custom shadow foam and tool control cabinets with proximity reader access, and task-specific kits for engine, airframe, and avionics work.
Cables, Connectors & Harnesses
The connection between a GPU and an aircraft's external power receptacle requires specific connector types matched to the airframe. The most common configuration is the NATO-standard 3-pin oval connector, used on most Cessna models and many military aircraft. Piper aircraft typically use a round plug design. Commercial aircraft requiring 400Hz AC power use larger, specialized connectors rated for higher voltage and current.
Extension harnesses and custom cable assemblies are available for installations where the GPU cannot be positioned directly adjacent to the aircraft — a common scenario in crowded hangar environments or when a single TRU serves multiple aircraft positions. Cable gauge, length, and connector termination must be matched to the power output of the GPU to avoid voltage drop at the aircraft receptacle, particularly during the high-current starting phase.