On-board device helps prevent volcanic ash damage to aircraft

New technology could help alert airlines to dangerous build-ups of volcanic ash in aircraft engines – potentially saving millions of pounds in unscheduled repairs.

A group of European firms have adapted technology used to analyse emissions from industrial chimneys to create a device that can identify particles of volcanic ash as small as 10 microns within an engine feed.

Instead of helping pilots avoid clouds of volcanic ash – as is done by the system adopted by Easyjet following the 2010 eruption of an Icelandic volcano – the new device would provide real-time monitoring of the engines themselves, allowing repair crews to schedule maintenance if there were a build up of ash particles.

The technology, developed in the UK by emissions specialist The Greenbank Group and product development company Pera Technology, uses lasers to analyse dust particles in the engine and identify if they are volcanic in origin by comparing them to a database.

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The new system combines laser detectors with image-processing software.

Sample particles taken from the engine are fed into a plenum chamber that slows them down due to its greater air pressure. Two laser beams are then fired at the particles in short succession and the difference in the way the two beams are refracted as the particle changes direction (a property known as birefringence) can be used to identify the presence of volcanic ash.

A secondary system then repositions the particles and captures a very high-resolution image, which is analysed by software to determine the proportion of ash in the sample by spotting the unique structure of volcanic material.

Richard Baker, project manager from Pera’s UK Intelligent Systems Research Institute, told The Engineer the group had yet to identify the best way for the device to be used on an aircraft but that it had the advantage of not affecting the aerodynamics of a plane.

The Easyjet-sponsored “Avoid” system, for example, comprises an infra-red camera attached to the the side of the fuselage or the underside of the wing.

‘Other technology that has been bolted to an aircraft hasn’t really progressed for a good few years now,’ said Baker. ’Our device comes in a lot smaller so the airframe wouldn’t need to be retrofitted, it could all be done internally – we’d take a bleed off the engine.’

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Pera Technology says the new system could be fitted internally rather than retrofitted to an aircraft’s aeroframe.

The system has reached the prototype stage after work to integrate laser and camera technology to allow it to capture the images of the ash particles fast enough and them process them to provide real-time analysis.

More research is now needed to further slow down the particles and to speed up the image-capturing process, alongside work with airlines to determine the most appropriate application for the technology in order to commercialise it.

Pera and Greenbank were joined in the EU-funded “Aida” project by aerospace companies Aerocare and Aerostar, software experts Innora and WLB, and injection moulding company Lenis.