The locking spring washer, code 06.16169-0004.2, is a critical fastening element designed to secure bolted connections in the MAN L21/31 engine against loosening caused by vibration and dynamic operating loads. Its spring-like geometry creates a constant preload and additional friction between fastening surfaces, ensuring that bolts maintain their required clamping force during long operating cycles. Manufactured from high-strength, fatigue-resistant materials, the washer maintains its elasticity even under repeated thermal and mechanical stress. Though compact in size, this component plays a vital role in safeguarding engine assemblies, supporting structural integrity, and enhancing the reliability of marine and stationary diesel engine installations.