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For over 20 years I worked on flightlines around the world, maintaining a variety of U.S. Air Force fighter, attack and helicopter airframes. During this time, as one can imagine, I was required to use numerous different test sets to ensure these critical assets were always ready to perform their intended mission. The test sets ranged in size from small handheld lamp test sets to “advanced” test sets which took multiple people to transport.<Read More>

During all my years of handling these various test sets, I had no idea what was inside the test set that contributed to its overall size, what I was getting for the size, but did it really matter? The reality is most of the test sets I utilized, which in many cases are still being utilized, are a product of the technology at the time, of course, but which means they are dated and cumbersome. I remember one particular test set, which was fielded as my career was winding down, was in fact developed nearly 20 years prior. Given the long procurement times for such equipment, a newly-fielded system might already be old and dated.

Size must be carefully considered when reviewing new or potential test sets, for two important reasons: First, is the test set large enough to support all the circuitry needed to complete all required testing PLUS support future needs? Second, what is the expected ROI of the “size”?

The second one is a bit trickier, but let me quickly explain.

Some test sets are used to test a single system in a single environment (O-, I- or D-level testing), which allows for the test set to be created with the minimum level of circuitry and ruggedization to satisfy the requirement. However, others are designed to be used in multiple environments (O- and I-level, for example) or used to test different systems. When this occurs, designers are often required to build in circuitry and hardware which may never be utilized in one environment or the other to meet all the different requirements, many times resulting in a large, complex, costly test set.

For example, let’s take the power needs of the test set, where I-level test sets normally require additional circuitry to accommodate this testing. Another example is the ruggedization needs for a test set to operate in an O-level environment, which can consume much of the budget when the test sets are large and bulky. Many times the O-level test set does not require the additional power circuitry since it can obtain power from the aircraft, and the I-level test set does not need to be as rugged to operate in a backshop environment. Combining all of the requirements into one unit might seem like the best solution to cover every base.

But the choice to bundle multiple test capabilities into one large package could be a false economy. Not only might it be less expensive to acquire specific test tests for O- and I-level test, but careful consideration must also be given to the life cycle cost of large and cumbersome test sets. Additionally, if one function fails, it is more expensive to replace a large test set than to just replace a specific smaller piece of equipment.

In the end, size probably does matter, but not if it comes at a cost to functionality by chasing the holy grail of small size, or destroys the budget trying to combine too many systems. Set your requirements, think about the future and demand the best for your maintainers.