The Hobart JetEx series ground power units (GPU) are in my opinion the most widely used diesel driven 28.5vDC GPU in the USA (and possibly the world).  It is a common occurrence to see these unit on the ramps at FBOs, corporate flight departments, regional airlines and military installations (I also see, well more like “hear” many Davco Magnum units out on the regional airline ramps).

While Hobart may be the “industry standard” and name brand in the aviation world; this is a large market segment with many other companies manufacturing DC & AC GPUs (some higher quality and some of much lower quality).

With this said, while the JetEx4D has been replaced with the newer JetEx5D my focus for now is on the JetEx4D.  As there seem to be many more JetEx4D units on the ramps than the JetEx5D, and many customers often call or email me to receive pricing on used or refurbished JetEx4D units.  A customer could expect to pay the following for the units mentioned above in refurbished or good used condition:

• Hobart JetEx4D (1983 to 1992) ~ $16,000 to $22,000
• Hobart JetEx5D (1995 to 2005) ~ $19,500 to $27,000
• Davco Magnum (1993 to 2005) ~ $16,000 to $25,000

With this said, I have chosen to compare a rebuilt Hobart JetEx4D to a new JetGo GPU, as they have similar price points.  My selection for this test was the JetGo 550Mti, which is the most popular of the JetGo models and leads the diesel-electric hybrid market in both technology and function.

My test method was through the use of Cannon L-28 and L-29 Load Banks, which accurately simulates the amperage draw of both aircraft engine starts and the continuous loads you can expect from a regional aircraft or mid-size business jet running avionics, lights and the electrical conditioned air systems where applicable.

While both units performed very well, and provided more than enough power needed to safely start and support the power needs of most aircraft; the JetGo unit slightly outperformed the Hobart unit in response time, amperage/voltage and engine “bog”. The JetGo 550Mti also provides more peak starting amperage than the venerable Hobart JetEx4D (550Mti = 2300 peak amps and JetEx4D= 2000 peak amps) and both easily put out 550 continuous amps. Though the JetGo was noticeably quieter and burned 56 percent less fuel over the course of the test operations.

In addition to the previously mentioned, the JetGo unit was much smaller, lighter and easier to use; with little room for any operator error that could lead to hot starts or aircraft damage (the JetGo was basically push button operation with full automation).  Another advantage of the JetGo was its ability to provide 24vDC power without the engine running, allowing customers with 24 volt avionics packages the ability to run preflight checks and avionics updates inside the hangar (via the onboard hybrid battery system).

While both the JetEx4D and JetGo 550Mti held up to expectations and performed similarly during the load bank tests; they are further separated by the low level of maintenance the JetGo GPU required during the preventative maintenance procedures.   Not to mention the price, as the cost of a new JetGo is similar to the cost of a rebuilt JetEx4D….