ST5

Common issues

• Compressor fouling (reduced air flow, surging tendency)
• Bearing wear (axial and radial play exceeding limits, increased vibration, oil leakage)
• Turbine-side fouling (reduced efficiency, increased exhaust back pressure, higher exhaust temperatures)
• Rotor imbalance (excessive vibration, bearing damage, potential for rotor contact with casing)
• Oil leakage from bearing casing (internal or external, leading to oil consumption or contamination)
• Air filter clogging (reduced engine performance, increased compressor wear)
• Cracks in turbine casing or exhaust gas manifold (hot spots, gas leaks)

Inspection checklist

• Visual inspection of compressor wheel for fouling, erosion, or foreign object damage (FOD).
• Visual inspection of turbine wheel and nozzle ring for fouling, erosion, cracks, or FOD.
• Check axial and radial bearing clearances (rotor play) using a dial gauge when the engine is stopped and cold.
• Inspect for oil leakage around bearing casing, oil inlet/outlet pipes, and air/gas seals.
• Check condition of the air filter element; clean or replace as necessary.
• Inspect exhaust gas casing and manifold for cracks, hot spots, or signs of gas leakage.
• Verify security of mounting bolts and connections (air, exhaust, oil).
• Manually rotate the rotor (if safe and accessible) to check for free movement and absence of rubbing.
• Monitor turbocharger speed, boost pressure, and exhaust gas temperatures during operation for abnormal readings or surging.

Service intervals

Typical wear limits

Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.

Critical spares

• Bearing cartridge assembly (thrust and journal bearings)
• Oil seals and O-rings for bearing casing
• Air filter elements
• Gasket sets for casing joints
• Cleaning agents for compressor and turbine washing
• Nozzle ring (if applicable and prone to wear/fouling)

Safety

• High temperatures of turbine casing and exhaust gas piping (burn hazard).
• High-speed rotating components (rotor burst risk if severely imbalanced or damaged).
• Pressurized air and exhaust gas lines (potential for leaks or sudden release).
• Oil mist or leakage from bearings (fire hazard, especially in hot engine rooms).
• High noise levels during operation (hearing protection required).

Class survey

Class surveyors typically verify maintenance records (running hours, overhaul history), inspect externally for leaks, damage, and secure mounting. They will often require bearing clearance checks (axial/radial play) during internal inspections (e.g., every 2.5 years), confirm rotor free rotation, and check the condition of safety devices (e.g., overspeed trip, alarms). Documentation of spare parts onboard and confirmation of regular cleaning procedures are also common points.