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The BBC News article The Jet Engines with Digital Twins describes engineers monitoring measured versus modeled behavior of jet engines, and deviations between them signaling possible need of maintenance.

The following mention of sand:

One of the most useful parts of the digital twin is that it measures a huge number of factors that the engine faces throughout its lifetime -- some flights have more people on them then others (that will put more strain on the engine), some cities (like Abu Dhabi) have a lot of sand in their air, and some pilots push their engines harder than others. “With the twin...I can learn that the pilot is a cowboy and pushes the engine. The fuel burn we see will be different with different pilot. The digital twin remembers every one of those events. (emphasis added)

made me wonder if modern jet engines monitor and record exposure to particles of dust or sand. If so, roughly how do the airborne particle monitors work - do they monitor the size distribution, or just count number over a certain threshold of some kind?

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    $\begingroup$ I don't have sources to back it up but I believe the engines are checked regularly for damage, particularly the leading edge of the compressor & turbine blades, which gives a good idea of the amount of sand/dust ingested. I'm not aware of any sensors for such a thing. If a pilot is concerned about ingestion of large particles they could raise it with their maintenance teams. $\endgroup$ – Notts90 Feb 26 '17 at 15:44
  • $\begingroup$ @Notts90 Hopefully that pilot's concern would not have triggered by a sudden loss of power. I suppose on or near the ground air traffic control would be aware of a sudden increase in sand/dirt, and at high altitude a volcanic eruption would have been noticed and characterized fairly quickly. Anyway, a particle monitor system would quantify the exposure without a need for maintenance, but maybe there's no practical need for it in reality. $\endgroup$ – uhoh Feb 26 '17 at 16:04
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    $\begingroup$ I've seen a turbine blade out of a eurofighter that had been to Afghanistan and was removed during overhaul because the sand had worn away too much of the leading edge. There was quite a lot of damage but apparently the engine still ran, just not as efficiently. So I think a sudden loss of power is unlikely unless you took in a lot at once. $\endgroup$ – Notts90 Feb 26 '17 at 16:10
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    $\begingroup$ @Notts90: There is likely some similarities between sand and volcanic ashes (though the melting point if different), the latter could shutdown an engine. $\endgroup$ – mins Feb 26 '17 at 17:33
  • $\begingroup$ @Notts90 I spoke too soon! According to this answer a practical need in reality has been proposed and is indeed being considered. $\endgroup$ – uhoh Feb 27 '17 at 0:46
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As of now, there are no commercially available engine particle ingestion sensors, though a few are under development. One of the companies involved in development lays out the reasons for the absence of any such sensors:

As of today, no commercial off-the-shelf particulate sensor is in use because of the special design and difficult requirements for operation and performance in this harsh environment, according to Dr. Hai Lin of Hal Technology in Fontana, California.

There are multiple sensors under development like the Dual Optical Embedded Dust Sensor which is used to determine the particle ingestion by the AGT1500 engine in M1 Abrams, where dust and sand is a bigger problem, if anything.

All of these sensors work on a similar principle- they measure the scattering of light by the particles using a optical sensor.

The sensor detects light scattering from moving particles as optical pulsed signals whose amplitudes are proportional to size and whose number is proportional to concentration. This sensor technology can determine particle size, distribution, concentration and further be extended for composition.

In future most of these systems are expected to available commercially, as

While continuing to advance this technology for particulate composition determination, Hal Technology is pursuing a licensing agreement or partnership with sensor or engine manufacturers to have the sensor integrated into engine heath management systems of the future.

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  • $\begingroup$ Thank you for the helpful links and background + current status information. Had the AGT1500 made it into a helicopter as a PLT27, it might have retained its particle sensor. According to the Wikipedia GE T700 article (selected over the PLT27), it featured "...an inlet particle separator designed to spin out dirt, sand, and dust." $\endgroup$ – uhoh Feb 27 '17 at 0:42

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