How to choose a ground power unit (GPU) for your helicopter or turboprop
Starting unit or continuous power, 26V or 28V, 92 Ah or 180 Ah, one unit or two in parallel: the four decisions that pick the right GPU, with the specs of each Hawker Aero model.
Starting the engine, or powering the aircraft?
“GPU” is used for two different jobs, and they need different equipment.
Engine starting
A portable battery starting unit delivers a very high current for a few seconds to start a turbine engine, anywhere: hangar, ramp, helipad or a remote site. This is what the Hawker Aero GPUs are for.
Continuous power
For avionics checks, maintenance and long ground operations you need continuous DC power from a rectifier / power supply connected to the mains, or a fuel-powered GPU at an airport.
Both
The GPU 26180 includes a 30 A rectifier / power supply, and 50 A and 60 A rectifiers can be connected in parallel to a GPU for maintenance work.
Not sure which you need? Compare battery, lead-acid and diesel units in lithium vs lead-acid vs diesel GPUs, or see the maintenance power supplies.
Voltage: 26V or 28V
Most helicopters and turboprops use a 28 V DC system, so a 28V unit (GPU 2880 or 28180, 28.5 V nominal) is the right choice. Some aircraft have low over-voltage protection and need a 26V unit (GPU 2680 or 26180): the Leonardo AW139, the Sikorsky S-76D, the Pilatus PC-6 and PC-12, the Embraer Phenom 100/300 and the Eclipse 500.
Always check the ground power limits in your aircraft maintenance manual (AMM). We confirm the right model with every quote.
Capacity: 92 Ah or 180 Ah
92 Ah · 18–19 kg · 2,700 A peak
GPU 2680 (26V) and GPU 2880 (28V). For light and medium helicopters and turboprops, and the easiest to carry: one technician takes it to the aircraft.
180 Ah · 34–35 kg · 5,500 A peak
GPU 26180 (26V) and GPU 28180 (28V). For medium and heavy aircraft, cold mornings or many starts per charge, with roughly twice the energy.
The four models
One unit, or two in parallel?
All Hawker Aero units are modular: connect two or more with the optional parallel cable to double or triple the output and the capacity, and still use each one on its own. It is how large aircraft are started with portable units: two GPU 2880 instead of one 28180, or two GPU 28180 for the Airbus C-295.
Quick guide
| Your aircraft | Recommended |
|---|---|
| Light and medium helicopters and turboprops with a 28 V system (H125, H135, Bell 206/407/412, AW109, King Air, Caravan…) | GPU 2880 · GPU 28180 for more starts per charge |
| Aircraft with low over-voltage protection (AW139, Sikorsky S-76D, Pilatus PC-6 / PC-12, Embraer Phenom 100/300, Eclipse 500) | GPU 2680 · GPU 26180 (26 V) |
| Larger aircraft (ATR 42/72, H175, Super Puma, AW101…) | GPU 28180, or two GPU 2880 in parallel |
| Very high starting demand (Airbus C-295 / CN-235 / C-212) | Two GPU 28180 in parallel |
For your exact model, see our guides by aircraft (AW139, H125, H135, Bell 407 and 412, S-76, King Air, PC-12, Caravan, ATR, C-295) or the full compatibility list.
Practical checks
Connector and charger
Supplied with a 2 m aircraft cable with NATO connector and a charger for 90–240 V AC, 50/60 Hz.
Temperature
Rated from −30 °C to +60 °C (−22 °F to +140 °F), for cold starts in winter and hot ramps in summer.
Care and transport
Never discharge below 25 V: it damages the cells. UN38.3 certified for air transport of the batteries.
Frequently asked questions
Do I need a 26V or a 28V ground power unit?
Most helicopters and turboprops have a 28 V DC system and use a 28V unit. Aircraft with low over-voltage protection, such as the AW139, Sikorsky S-76D, Pilatus PC-6 / PC-12, Embraer Phenom and Eclipse 500, need a 26V unit. Always confirm in your aircraft maintenance manual (AMM).
Can a battery GPU power the aircraft during maintenance?
No. Battery starting units like the Hawker Aero GPUs are designed for engine starting only, and must not be discharged below 25 V. For avionics checks and maintenance you need continuous DC power from a rectifier / power supply: the GPU 26180 includes a 30 A rectifier, and 50 A and 60 A rectifiers are available.
How many starts do I get per charge?
It depends on the aircraft, the outside temperature and how the engine is started. The 180 Ah units store about twice the energy of the 92 Ah units, and units can be connected in parallel when you need more.
Can I take a lithium GPU on a plane or ship it abroad?
Hawker Aero GPUs are UN38.3 certified, the test required to transport lithium batteries by air. We ship them worldwide from Spain.
Which connector and cable do they use?
All models are supplied with a 2 m (6 ft) aircraft cable with NATO connector and a charger for 90–240 V AC mains.
Keep reading
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