Borescoping – looking into the most remote places
Modern engines are now so large, that even adults can stand straight in the air intake. The complex technology inside, however, is extremely difficult to access. It is not always possible to achieve a precise diagnosis purely by analyzing data from engine condition monitoring. In certain cases, precise fault-finding has to be carried out on the ground or the assessment based on data analysis has to be verified. A visual inspection to identify wear and damage to a compressor blade, for example, used to mean disassembling almost the entire engine, costing vast amounts of time and money. Today, most Lufthansa Technik visual inspections are carried out as mobile services using a borescope.
In the beginning, the borescope lens was guided to the inspection point using a rigid tube, but today the process is predominantly carried out with a so-called flexoscope. Instead of a rigid tube, this tool has a flexible hose with the optics and suitable imaging sensors fitted at the distal end. The image is no longer transmitted to the screen using lenses or fiber optics; instead, it is all digital. Even components located deep inside the engine and not accessible via any straight path can be inspected with flexoscopes, which can be several meters long. The borescope equipment as a whole has also become significantly smaller, lighter, and easier to operate.
Lufthansa Technik is already deploying latest generation of video borescopes, with 3D measuring technology. They allow for optical measurement of localized damage. With suitable measurement and analysis software, engine rotor blades and their chord lengths can be scanned, measured and calculated with great precision. The software-controlled platform can be updated and extended in the future. The probes can be swapped and are suitable for cavities and gaps up to four millimeters in diameter. Smaller damage to rotorblades can be repaired with a so-called blending endoscope. This technology is comparable with minimal invasive surgery in the medical field and saves disassembling the engine. The condition of the engine can also be regularly inspected, allowing for predictions of wear and tear. This makes more precise and individual planning of maintenance work possible.
Lufthansa Technik personnel undergo several days of basic training at Lufthansa Technical Training to learn how to use the borescope and its associated hardware and software. There are then further training days for each engine model. This training program is worthwhile for Lufthansa Technik, as just a single engine disassembly saved with borescoping recoups the purchase cost of the equipment.