Science & technology | Inspecting airliners

Strike out

Uncrewed aircraft may help crewed ones return to flight more rapidly

CHECKING an airliner’s wings and fuselage for damage after it has been hit by lightning or suffered a bird strike is more than just a time-consuming nuisance. In the cut-throat world of commercial aviation, time is money, and a plane in a hangar is a plane not earning its keep. At the moment, conducting such an inspection means employing engineers to stand on elevated mobile platforms so that they can pore over an affected aeroplane’s surface seeking out dents, holes or high-voltage skin burns which might be in need of repair. For an average plane, this takes about ten hours.

But that may soon change. In recent tests at Luton Airport, near London, a drone called Riser—the brainchild of Blue Bear Research Systems, a drone-builder based near the airport, and Createc, a sensing-and-imaging company in Cockermouth, in the north of England—completed equivalent surveys of an Airbus A320 belonging to EasyJet, a budget airline, in a mere 20 minutes.

Using a drone to look into a plane’s nooks and crannies makes sense, but there is a wrinkle. For obvious reasons, the authorities do not like robot aircraft flying around airports. Drones can therefore operate only inside hangars, and only when the doors are shut. Most drones, though, rely on the satellites of the Global Positioning System to know where they are, and GPS does not work well indoors.

Riser gets around this by using lidar for navigation. Lidar is similar to radar. It fires off pulses of electromagnetic radiation, records when these pulses’ reflections return, and calculates how far away the object they have bounced off is, based on how long each pulse took to come back. The difference is that lidar employs light waves in place of radio waves and thus, because light has a much shorter wavelength than radio, has a far finer resolution.

Seven small lasers on board a Riser beam 40,000 pulses of infra-red light a second into the craft’s surroundings. Sensors on board record the reflections of these and pass the results to a computer. This uses them to map both the walls of the hangar and the shape of the aeroplane within. It then works out precisely where the drone is with respect to both.

Using this information, a Riser drone can navigate its way around an aeroplane’s surface, keeping a distance of about a metre away from it at all times, and recording as it flies a high-resolution video of what it sees. The video automatically tags any damage, permitting a human engineer to find it easily and thus decide whether to repair the plane or put it back into service.

All this could save airlines a lot of money. EasyJet itself is planning to install Riser at ten airports by the end of next year and Yoge Patel, Blue Bear’s boss, says her drones have attracted the interest of several other airlines, and also an aircraftmaker. Nor are aircraft the only safety-critical systems that Riser might be deployed to examine. It was originally designed for, and remains intended for, the remote inspection of nuclear reactors. So if, in future, you see a drone buzzing around your local power plant, do not automatically assume it is up to no good.

This article appeared in the Science & technology section of the print edition under the headline "Strike out"

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