The Kingisepp Machine-Building Plant (KMZ) will carry out a major overhaul of four M504A-3 marine diesel engines under a state contract. The enterprise will have to restore one of the most complex domestic engines of this class with complete disassembly, parts inspection, unit repair, and subsequent testing.

The M504A-3 diesel engine is based on the 56ChNSP16/17 engine and belongs to the family of high-speed multi-cylinder marine power plants. It has 56 cylinders, a seven-beam star-shaped layout, and operates in conjunction with a two-stage reverse-reducer. The unit's power ranges from 3500 to 4000 kW.

At nominal load, the engine can consume from 714 to 844 kg of fuel per hour, and daily consumption can reach almost 20–23.5 thousand liters.

The M504A-3 has a complex design, so a full repair of this engine directly on the vessel is practically impossible. Restoration requires dismantling, deep defect detection of parts, replacement of worn elements, and post-assembly inspection on special equipment.

For the repair of new engines, the enterprise uses its own production base, components, and technical documentation obtained from the developer — PAO "Zvezda". After restoration, the diesel engines must undergo bench tests to confirm their operating characteristics.