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With support from the Hamburg Departmental Authority for Economic
Affairs, Transport, and Innovation, Lufthansa Technik brought promi-
nent partners on board: the Institute of Aircraft Production Technology
at the Hamburg University of Technology (TUHH), which is responsible
for handling – and VMT. Collaborating with partner company Espace,
with Dr. Werner Neddermeyer as project manager, the Pepperl+Fuchs
subsidiary is responsible for sensors and image processing within
the project. Marc-André Otto, who works in R&D at VMT and is deeply
involved in the project together with Sönke Bahr, explains: “At VMT, we
have the good fortune to be involved in unusual projects fairly often.
But this one is definitely very special.”
Tiny Cracks and an Immense Volume of Data
The team had major challenges to deal with. First, there was the com-
ponent in question: the external flame tube of a CFM56 engine. It has
a diameter of approximately 750 mm and a height of approximately
200 mm and, because of its complex shape, it is very difficult to scan
in one piece. The only possible way to achieve the necessary high
image resolution was a white light interferometer. Because white light
contains a large number of different wavelengths, it is possible to take
accurate measurements. But the term does not actually say anything
about its color.
In the AutoInspect project, the interferometer uses red light. The
interferometer is susceptible to vibration, an issue that was resolved
through the measurement system design. An industrial robot with
six-axis serial kinematics guides the sensor components, while an
external rotation axis moves the flame tube. The whole system is
placed on top of a thick steel plate that is isolated from its surroundings
via air springs. There are over 100,000 measurement fields per tube,
yielding well over 100 gigabytes of data that need to be processed.
“Transmitting, analyzing, and representing such an incredible volume
of data wasn’t easy, but we did it,” Otto says. In addition, a damaged
component often has local and global repercussions. Scanning the
component with the high-precision interferometer quickly becomes
impossible, because the measurement range is not very deep. This
problem was solved with the LR 300 laser triangulation sensor from
Pepperl+Fuchs, which helps adjust measurement positions to the
current circumstances. After four years of research and trial phases,
Lufthansa Technik now plans to obtain approval for the new method
from engine manufacturers. After that, the method will be industrialized.
While the AutoInspect project is running, another project – AutoRep –
has also been launched. After all, once automated crack detection is
in place, automatic repairs should follow. “We’re on the right track, but
there’s still plenty of excitement ahead,” says Otto.
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