GE’s New Method to Assess Airworthiness
The back end of today’s aircraft turbine engines is occupied by extremely valuable, extraordinarily engineered parts called compressor blades. They are subjected to 13000 C heat and ultra-intense pressure. Each of these parts is manufactured to precise dimensions, is made of exotic metal compounds, is coated with protective compounds, has miniscule cooling cavities and pinpoint exterior holes – all of which allow it to perform under in this intense environment. Deviations, created during flight times, from its design standards may diminish performance and/or create risks.
For those reasons, airline maintenance of these turbines requires frequent inspection, repair and overhaul. Any time that a powerplant is off a wing, the airlines incurs heavy expenses—loss of productivity, repair maintenance technicians and replacement parts.
Today, this segment of an engine can be accomplished with an endoscope. A camera on a flexible tube is inserted through a hole in the engine’s casing. But the view is limited.
The folks at GE have a better idea. Their wizards at the GE Global Research Center in Niskayuna, New York tasked a team to design a new method to assess the airworthiness of these blades. Don Lipkin, a chief scientist there, and his colleagues Todd Danko and Kori Macdonald are studied the problem and have devised a solution. They have designed tiny robots which can venture inside an engine to inspect its innards and carry out any necessary repairs. Eventually, these robots may be able to work while a plane is waiting at a gate between flights.
The first of these micro AMTs, actually a flexible material about the size of an envelope, will follow a rack-and-pinion track into the compressor section and will can photograph internal surfaces adjacent to the blades as it passes. Once its job is done, it can be pulled out on a cord.
For the mechanically challenged, here is a diagram of “rack and pinion” (the actual plastic track is considerably smaller):
And here is a crude drawing of how the AMT robot will be positioned in a turbine:
- AMT robot #2, a few centimeters square, would creep inside the compressor section on caterpillar tracks.
- AMT robot #3 uses magnetic wheels. These let it grip surfaces, and thus work upside down, if necessary.
- Ostensibly AMT Robots #2 and #3 have tiny extensions added so they perform repairs. These AMTs are designed to inject ceramic coatings from a cartridge of material to fill in any damaged areas. These robots can also carry small grinding tools, to smooth down ragged surfaces.
The good news for the human AMTs is that these robots require someone to control them using a tablet.
The technology is most promising for the AMT robots will:
- produce much finer monitoring of an engine’s wear and tear
- detect and remove airborne particles, particularly a risk in polluted regions, from blocking the microscopic cooling channels that help stop an engine melting.
- detect and repair abrasions, especially from wind-blown sand grains in places such as the Middle East and volcanic ash
- repairs made may not be as substantial as those performed during an overhaul, but the robot repairs can extend the time between major overhauls.
- provide a whole new granularity of data. The robots would collect information about wear, abrasion and other indicia of the engine’s performance.
- Those numbers will be loaded into the relevant GE engine model’s “digital twin”. These computer files are virtual replicas and their data banks include almost real time operating data sent via satellites from sensors mounted inside engines. The twins are the ultimate SMS machines for their purpose is to detect emerging risk trends and follow the SMS rubric of aiding in identifying solutions.
- This extends the horizon of preventive maintenance. The robots’ data should lead to earlier corrections and mini AMTs may be able to perform the repairs on the fleet while the powerplants are on the wing. Thus, they may reduce unscheduled visits to the workshop.
GE has a great idea. Robot AMTs’ may lead to even higher levels of safety.
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