OEM requirements for bond and loop testing

When it comes to matching OEM requirements for bond and loop testing with the right tool, it can be a minefield.  As an MRO, your first point of call should be the AMM (maintenance manual). 

However, some OEMs are more prescriptive than others.  And with a broad range of similar tools available on the marketing all claiming to comply with OEM requirements, how do you know for sure which tool is right?

We’ve broken down our range of tools by original equipment manufacturer, to help explain the differences:



All loop resistance testing on Airbus aircraft must be carried out at 1000Hz, so the BLTU4 is the right tool. Airbus do not require joint testing, only loop and bond. We can support with proving equivalency to Airbus for using the BLTU4 within your operation – get in touch with us for details.



In comparison, all loop resistance testing on Boeing aircraft must be carried out using 200Hz. In addition, Boeing also demand specific joint tests, variance tests and stray current tests.  The BLRT is the recommended tool for this, and it’s approved by Boeing because it complies with their requirements.



Bombardier are aligned with the Airbus specification of 1000Hz, so we therefore recommend the BLTU4.



Embraer follow Boeing in terms of frequency and types of test required, so the BLRT would be the most suitable tool.


What about the ExLRT?

The ExLRT is our Intrinsically Safe loop resistance tester. It’s been developed specifically for safe use in fueled zones.  It’s approved by Boeing and is a specified, named tool in their AMM.  Whilst both tools are suitable for use on Boeing (and therefore also Embraer) aircraft, the two models have separate specifications.  To  learn more about the differences between BLRT and the ExLRT, read this article.


Visit the dedicated product pages for BLRT, BLTU and ExLRT to learn more about each of our bond and loop testing tools. To learn more about the differences between our tools and the legacy Boeing-approved LRT, visit our blog and filter by ExLRT.


 BLTU application 3 - loop resistance and integrity of cable shields and bonding straps