ExLRT vs LRT: A full comparison

ExLRT vs LRT loop resistance tester: A full comparison

Can your business afford to not upgrade from the LRT?

If you’re an MRO working on Boeing aircraft, then it’s likely that you have a legacy ‘yellow-box’ LRT in your facility. You might use this regularly and are used to working around well-known flaws, or you may have heard colleagues talk about them whenever loop testing comes up.  Either way, time and time again, this tool is causing the same frustrations for countless businesses like yours across the globe.

Until recently, the only alternative loop tester authorised by Boeing was the ‘yellow box’ LRT made by BAE systems. The LRT (models 906-10246-3, 906-10247-3 and 906-10276-3) is a heavy tool which uses ageing technology. It requires off-site calibration and causes testing downtime when the batteries need charging.

You’re not stuck with the LRT!

We’ve developed our range of tools specifically to resolve the inherent issues with the legacy equipment and have worked closely with The Boeing Company to achieve their approval.

We have two models approved for use by Boeing, which are simpler to use, and more operator-friendly than the LRT. These are the ExLRT (model XLR-9703-01) and the BLRT. Let’s introduce them, then see how they compare – ExLRT vs LRT.


The game-changing ExLRT is our intrinsically safe, lightweight loop resistance tester. It’s a step-change within the industry and offers fast, simple-to-use, easy-to-read testing packaged in a tough tool designed for factory floor and field applications.

The IS classification makes it perfect for MROs and environments where fuel/ hazardous materials are present. It’s also incredibly light and portable compared to the legacy ‘yellow box’ tool.

The ExLRT is approved by Boeing for carrying out prescribed loop resistance testing.  It is a specified tool listed in Boeing AMMs (Aircraft Maintenance Manuals).

ExLRT vs LRT loop resistance tester: A full comparisonExLRT vs LRT loop resistance tester: A full comparison


The BLRT is an extremely powerful tool that can measure bond, loop and joint resistance. It is approved by The Boeing Company for use on unfuelled aircraft and is listed in the Boeing Tooling and Equipment Database.

ExLRT vs LRT loop resistance tester: A full comparisonExLRT vs LRT loop resistance tester: A full comparison

Size matters

The ExLRT is over 82% lighter than the LRT. Not to be outdone, the BLRT is less than half the weight of the LRT. To learn why this is such an important difference read our ‘size matters’ article, which is part one in our comparison series.

Designed for MRO use

The legacy LRT was designed in a lab, for lab use. It became commonly used in MROs through lack of an alternative tool, but it isn’t fit for purpose. The ExLRT was developed with MRO use in mind. It has several features to make operation easier and faster, including LEDs and button controls on the probe and single operator use. [Part two] in our comparison series talks about these features in more detail.

Safe to use on fuelled aircraft

The ExLRT is certified as Intrinsically Safe by all 4 global IS standards. This means that no matter where you are in the world, the ExLRT is safe to use on fueled aircraft according to your country’s safety standards. Learn more about the different standards, which one is used in your country and the latest status of the IS classification of the legacy LRT in our dedicated comparison here.

The vital statistics

ExLRT vs LRT loop resistance tester: A full comparison


Next steps to upgrade from your LRT

With approval from The Boeing Company and compared using the criteria listed above, it is clear that MK Test’s range of loop resistance testers are more MRO-friendly than the legacy LRT.

The systems are ‘good to go’ straight out of the box and are available from stock within 1-2 weeks. You could have a technically advanced, more robust and easier to use tool on your site within days.

Want to learn more?

For more information about our loop resistance testing tools including demos and pricing, please visit the ExLRT and BLRT product pages and complete the enquiry form.

You can also download the information on this page in brochure format here.