Technology That Makes a Difference
Military & Industrial Applications

With funding from the U.S. Department of Defense (DOD), LURACO Technologies, Inc. developed an infrared optical sensor "IR sensor" that will be used for engine fluid quality monitoring in U.S. military aircraft.

LURACO's IR sensor will initially be targeted at Apache (AH-64) and Blackhawk (UH-60) aircraft. In the future, it may be integrated into other military aircraft as well as industrial processing equipment, construction equipment and vehicles, and energy generation equipment. Much of this equipment currently is not monitored. By using IR sensing technology to determine fluid maintenance needs, the military would have an accurate, light-weight, compact, rugged, and highly reliable system built right into the aircraft engine that could save millions in maintenance costs.

Infrared (IR) absorption spectroscopy has been demonstrated as a suitable technique for lubricant and oils quality analysis. IR spectroscopy measures the unique absorption signatures of oil, from which their identity and concentration can be accurately determined. A preliminary investigation of infrared absorption spectroscopy for oil analysis using Fourier Transform Infrared (FTIR) spectra of both unused and used oil samples acquired with FTIR instruments in the laboratory is shown in figure 1 & 2.

Infrared absorption spectra of both used and unused oil samples show absorption structure that differs from sample to sample and is indicative of changes in the physical and chemical properties of the lubricant. These spectra can be used to monitor the depletion of oil additives, the formation of by-products through chemical reactions that might take place during the high-temperature operation of the engine, and any change in the oil's hydrocarbon chemical structure. These results indicate that infrared absorption spectroscopy is a viable technique for oil condition assessment and warrants further experimentation and analysis to understand the origin of different species and the variation of their concentrations so that they can be spectroscopically monitored.

Using infrared optical spectrum analysis, concentrations of many contamination compounds in oil can be identified. Figure 3 below shows the spectrum differences indicating changes in concentration of contamination compounds at specified wavelength ranges.

Optical sensors provide superior performance compared to other technologies and allow a quick and cost effective prediction of oil and fluid conditions. Oil and fluid analysis using optical spectroscopy by FTIR has been used in industry and laboratory. However, current FTIR systems are usually large and developed for laboratory use purposes only. In order to develop an in-line oil analysis system, the sensor needs to be compact. LURACO researched and developed a simple and cost effective IR sensor architecture for aircraft engine fluid sensing to detect infrared optical absorption coefficient shifts as fluid degrades.

  • Figure 1: Absorption Spectra Of Multiple Used Oil Samples [1, 2, 3]
  • Figure 2: Absorption Spectra Of Multiple Used Oil Samples [1, 2, 3]
  • Figure 3: Absorption Spectra Of New and Used Oil Samples [1, 2, 3]
  • Figure 4: LURACO's Aircraft Fluid Quality IR Sensor