BAE Systems is seeking to reduce the downtime required to test aircraft shielding systems with new upgrades to its Loop Resistance Tester (LRT). The company’s LRT, which was originally developed in 1998 for use on the Boeing 777, is a portable electronic instrument used to measure the integrity of an aircraft’s shielding and grounding systems. These systems, which protect flight-critical elements such as electronics and flight controls during storms, require routine testing to ensure their integrity.
As a non-intrusive method of testing, the LRT allows cable connectors to stay put, which eliminates the need for added system tests due to disconnecting and re-attaching connections. The LRT drives voltage into a loop, where voltage and current are measured and resistance of the loop is calculated. If this resistance is outside specified limits, bad joints can be isolated with joint probes.
BAE Systems says the LRT can detect latent defects in shielding systems, which helps to avoid aircraft downtime and loss of revenue. According to the company, one airframe manufacturer has noted that the LRT’s return on investment is realized after just one use, because the average downtime to replace a discrepant cable is three days.
With the LRT’s recent upgrades, BAE Systems is trying to add even more to the product’s value proposition. In addition to improvements made to meet current certification standards, the company says the new LRT will have longer battery life and more durable connectors and input devices. Obsolete parts have been removed thanks to a new main circuit card assembly and the battery has been switched to a lithium-ion style, which BAE Systems says will increase use between charges.
“The newly redesigned LRT is perfect for airlines, aircraft manufacturers and MRO organizations, as it can be utilized in all Class 1, Division 2 areas around fueled aircraft,” says Rich Hopf, director of airlines at BAE Systems. “The upgrade includes an improved clamp design which provides a durable shell to protect the LRT from damage, as well as a sleek profile that allows maintainers to test hard-to-reach sections of cable shielding.”
BAE Systems says the newly upgraded LRT will be available by the end of this year. The LRT is used in the field on several Boeing aircraft models and is used on the production line for the 777 and 737-NG to validate shielding and grounding integrity The company says Boeing has released requirements into aircraft maintenance manuals for all of its models to test Fuel Quantity Indication System wiring. According to BAE Systems, the LRT is applicable to any aircraft and is also used on several military aircraft.