Abstract: A system provides in-situ surface processing of an engine blade within an aircraft engine. The system includes an endoscopic processing instrument with a variable-angle tubular shaft. The processing instrument is inserted radially through a lateral access opening into the aircraft engine in a non-angled initial configuration. The lateral access opening is downstream of the engine blade. The processing instrument has a rotatably driven tool holder at a distal end of the shaft for a surface processing tool head. In an angled working configuration, a tool head inserted into the tool holder is applied to a flow edge of the engine blade. Furthermore, a process uses the corresponding system.