The stay bolt, code 102262, is a highly loaded structural fastening component of the MAN L21/31 engine designed to securely connect and stabilize major engine structures while maintaining the required clamping force during operation. In a medium-speed diesel engine, such fastening elements must withstand substantial tensile forces, cyclic combustion loads, vibration, and thermal expansion without allowing unwanted movement or loss of alignment between connected components. The stay bolt is therefore manufactured and machined to demanding mechanical and dimensional requirements so that the specified preload can be applied and maintained reliably throughout service. Correct installation, tightening, inspection, and condition monitoring are particularly important because deterioration or incorrect loading of a structural bolt can affect load distribution and the stability of associated engine parts. By maintaining structural rigidity and correct alignment, the stay bolt contributes significantly to safe operation, mechanical durability, and the long-term reliability of the MAN L21/31 engine.