Blending dents and dings on a compressor blade from outside an engine using a remotely-operated tool via a bore hole is a highly cost-effective way to carry out maintenance.
The engine can continue to operate, perhaps with minor compressor efficiency degradation, and does not need to be taken off wing for an unscheduled overhaul shop visit.
Rolls-Royce says, however, that only a limited number of specialist engineers are qualified to carry out bore-blending tasks – and they are not always immediately available when required.
In order to employ such experts more efficiently, the UK manufacturer has developed a robot that can be fitted to an engine by regular technicians and then remotely operated, via data link, by a specialist elsewhere.
The equipment, developed in partnership with the University of Nottingham, is at technology readiness level five and has been tested on full-scale engines.
R-R on-wing technology specialist James Kell said during a briefing at Farnborough air show on 17 July that the robot should enter production within a year or two.
The project is part of a wider effort to develop inspection and maintenance robots, although the devices are currently at different maturity levels.
In one of these projects, R-R is evaluating installing a network of permanent cameras throughout the engine, to spot and report potential maintenance requirements. Noting that the cameras would need to be protected against extreme heat to withstand conditions inside the core, Kell says the pencil-sized devices would extend into the gas path like periscopes, to supply visual information alongside other sensors in the engine.
A project dubbed FLARE, currently at technology readiness level 3, comprises a robot pair that can be inserted like endoscopes into the core via boreholes, in order to undertake thermal barrier coating patch repairs.
Kell says that one of the two snake-like devices will inspect the damaged area and remove the existing surface, while the other re-applies a temporary patch coating that would allow the aircraft to fly until a permanent repair can be made.
Under a project named SWARM that is being undertaken with Harvard University, R-R is studying the use of a flock of “collaborative” miniature robots with cameras, which autonomously crawl around engines to inspect hard-to-reach areas.
The multi-legged devices were inspired by cockroaches, says Harvard research fellow Sébastien de Rivaz, and are inserted – as a group – into the engine by a snake-like device similar to that in the FLARE project. Still at a conceptual stage (TRL2), the team is testing robots with a length of 4.5cm (1.8in) that weigh about 1.5g. The completed robots are projected to have a diameter of around 1cm, R-R says.
De Rivaz says the project is still four to five years away from being tested on an engine. But the concept promises to deliver significant savings in terms of time and money. Kell thinks it is feasible that inspections, which take five hours with a conventional borescope, could be completed in five minutes.