Ground power unit guide for Learjet aircraft. 28V DC GPU specs, TFE731 start requirements, and recommended equipment for the iconic light business jet family.
About the Learjet (40/45/75)
The Learjet is the name that defined business aviation. Although Bombardier ended Learjet production in 2021, the active fleet of Learjet 40, 45, 60, and 75 aircraft remains substantial — thousands of airframes that will continue flying for decades. Ground power for the Learjet family is well-established and straightforward: the Honeywell TFE731 engines that power most models are known quantities with predictable GPU requirements.
GPU Requirements
The Learjet's twin Honeywell TFE731 turbofans draw 2,500 to 3,500 amps at peak during ground starts. The TFE731 is a long-established engine with decades of operational data — its starting characteristics are well-understood and consistent. The smaller Learjet 40/45 with TFE731-20AR engines sit at the lower end of the current range (2,500A), while the Learjet 60 with TFE731-40 engines can approach 3,500A. Sequential engine starts require 30 to 60 seconds of GPU recovery time between starts. Continuous power for avionics (typically Collins Pro Line 4 or Pro Line 21) runs 300 to 400 amps.
Cold Weather Considerations
The TFE731 is well-suited to cold-weather operations, but the combination of cold turbofan bearings and cold engine oil still pushes peak current toward the upper range. Learjet operations at airports like Teterboro in January should spec GPUs at 3,000A minimum.
Recommended Ground Power Units
Battery Start Unit
Red Box RB100A
2,400A peak lithium GPU. Handles Learjet 40/45 starts in temperate conditions. Cart-mounted for ramp mobility at charter and FBO operations.
TRU
ITW GSE 2400T
Mains-powered TRU delivering 2,400A peak. Paired with the Learjet fleet for decades — a proven, reliable choice for fixed-base operations. Unlimited start cycles.
Combination GPU
Powervamp Coolspool 600
3,200A peak with 500A continuous. Covers the entire Learjet family with headroom. The combination format serves both start and maintenance needs.
Need help choosing? See our GPU Sizing Guide for a step-by-step approach to matching ground power equipment to your aircraft, or compare options in our Best GPU 2026 roundup.
Related Equipment
Similar Aircraft
Frequently Asked Questions
Are Learjet GPU requirements different from Citation GPU requirements?
Similar but not identical. The Learjet 45/75 (TFE731-20AR) draws 2,500 to 3,000A peak, comparable to larger Citations (XLS, Sovereign). The Learjet 60 (TFE731-40) draws up to 3,500A, approaching Challenger-class requirements. Both use 28V DC and NATO 3-pin connectors.
Can I use the same GPU for a Learjet and a King Air?
Yes, if the GPU is rated for the Learjet's higher requirements (2,500A+ peak). Both use 28V DC and NATO 3-pin connectors. A GPU sized for a Learjet will work fine on a King Air, since the King Air draws less current.
Now that Learjet production has ended, will GPU support continue?
Yes. The Learjet fleet will fly for decades, and all major GPU manufacturers continue to support the TFE731 engine family. GPU requirements don't change with production status — the aircraft's electrical specifications are permanent.