Using an unmanned aircraft to inspect an airliner would have been unthinkable just a few years ago. Now low-cost carrier EasyJet plans to deploy what it calls “drones” or unmanned aerial vehicles (UAV) at 10 maintenance bases across Europe by the end of 2016, to help inspect its Airbus A320s for hail and lightning-strike damage.
The developers of the system to be used by EasyJet, U.K. companies Blue Bear Systems Research and Createc, are now working with Thomas Cook Airlines to inspect larger Airbus A330s. They have a vision of a future in which a UAV is launched every time an airliner reaches a gate to continuously monitor entire fleets for damage.
Blue Bear and sensor specialist Createc began working on using unmanned aircraft systems (UAS) to inspect U.K. nuclear facilities for contamination. “We were doing indoor complex environment inspection work for the nuclear industry, which has a lot of similarities to the work we are now doing for aircraft,” says Gavin Goudie, Blue Bear director of operations.
“When EasyJet first proposed using UAS to inspect aircraft, they were looking for something off-the-shelf. But we said we could do it more intelligently. So they made facilities and engineers available and collaboratively, without any contract, we did a few demonstrations for their engineers, operators and management,” he says.
The result was a commitment from EasyJet to deploy the inspection system, initially as a managed service. “The key issue is a lightning strike resulting in an aircraft on ground. It can take 6-8 hr. to do a close, direct visual inspection for damage, and [it] requires staging and cherry pickers,” Goudie says. “That’s what makes the use of UAS to do inspections attractive.”
Initially the system will be used to enhance visual checks by engineers, but the team is developing the capability to automate inspections. “It is not replacing engineers. It is another tool, one they can deploy a lot more quickly with less planning,” he says. “It is giving a much better image database to engineers that can be collected and maintained so they can see changes.”
Key to this is making the system simple and safe to operate. A derivative of the Riser system developed for nuclear inspection, the Rapid aircraft inspection UAS is a 1-meter-sq. (10.8-ft.-sq.) quadrotor with caged props for safety. The vehicle carries high-intensity lighting and a high-definition camera and uses a laser system for navigation indoors (where GPS is not available) and collision avoidance.
Initially the system is semi-autonomous. The engineer will push the hovering UAS along the fuselage and wing and the vehicle automatically maintains a safe stand-off distance from the aircraft. But the team is now developing an automated system in which the operator will take the UAS out of its box and set it on the ground. The vehicle will know the aircraft it is to inspect, recognize a known point on the airframe, then take off to fly a predetermined inspection pattern.
The 3-D laser scanner used for navigation indoors can map an unknown room in 30 sec. or less, says Goudie. It is used to map the hangar and locate the aircraft, then to maintain a set distance from the airframe for safety and camera resolution. For now, Rapid is restricted to flying indoors, but the team is working with regulators and airports to gain approval to fly outdoors to inspect aircraft.
Equipped with a single camera, Rapid can scan an A320 or Boeing 737 in 10 min., about half the battery-powered UAS’s flight time. It will take longer to scan a larger aircraft, such as an A330, so different strategies are being evaluated, such as multiple passes or a greater stand-off distance to provide a bigger field of view, but this will require a higher-specification camera, Goudie says.
The vehicle weighs around 4 kg (8.8 lb.), but based on feedback from aircraft manufacturers on the maximum mass and impact energy they consider safe for close-proximity operations, the team is working to reduce this to 2 kg. This will also improve portability, he says.
Currently engineers must look for a burn mark caused by a lightning strike then measure the hole and determine if it is in a critical area. Automation will allow aircraft to be scanned and images compared with the database to detect new damage. The team is also working on 3-D scanning technology that can measure submillimeter damage automatically.
Development is being funded privately, with support from EasyJet and Thomas Cook, but the companies are now looking for U.K. government funding. “Ultimately we see this being used to do continuous monitoring of aircraft to enable more dynamic maintenance scheduling, and to provide continuous feedback to tailor maintenance,” says Goudie.
Initially the team plans to offer a managed service. “There will be a period of time before airlines are ready to buy their own systems,” he says. MRO providers are expected to be early customers, and Blue Bear and Createc are prepared to license the core sensing technology and database management techniques to other UAS providers. “We will become platform-agnostic,” says Goudie.