‘Best-in-class’ testing tool being added to Boeing AMMs

Press Release: Wellington, UK – 23rd January 2020

The ExLRT loop resistance tester has been awarded ATEX and IECEx Intrinsically Safe certification.  UL certification is due to follow within weeks, making this the most suitable loop testing tool available on the global market.

“The Intrinsically Safe certification of the ExLRT is the latest stage in what has been an extensive and close collaboration with Boeing to create a world-class tool.  The key requirement was an Intrinsically Safe design – once this was achieved, we knew the product would be well-received.”

Alan Wilson, Engineering Director at MK Test Systems
exlrt in situ
exlrt in situ

Benefits of the ExLRT

 The ExLRT is classified for Zone 0 useage, meaning it can be used on fuelled and unfuelled aircraft. Customers can now carry out loop resistance testing using a significantly lighter, advanced tool than the current industry standard LRT.

“We developed the ExLRT as a much-needed replacement for the existing LRT.  It eradicates the problems commonly associated with the current tool which is heavy, uses ageing technology and has obsolescence issues.  I’m incredibly proud of the team for their efforts in developing such a fantastic new product.”

Carl Bullock, Managing Director at MK Test Systems

Next Steps

A detailed document update programme is underway by Boeing to ensure operators are aware of the newly approval tool.  The aircraft manufacturer has released a Multi Operator Message (MOM) confirming the ExLRT is an approved alternative to the LRT. The MOM also advises that Boeing will grant a Non-Technical Objection (NTO) prior to the AMMs being updated in 2020.


The ExLRT is now commercially available; the first units will be delivered to Boeing within the month.

The addition of this latest model means that MK now offer a complete family of loop and joint resistance testers. A wide range of specifications and capabilities offer choice for both MRO and OEM environments.

The ATEX and IECEx certificates are available to view here.