SD 42SD

Common issues

• Bearing wear (thrust and journal bearings) leading to increased clearances, vibration, and potential rotor-stator contact.
• Fouling of compressor wheel and diffuser due to dirty intake air or oil carry-over, reducing efficiency and causing surging.
• Fouling and erosion of turbine blades and nozzle ring due to poor fuel combustion, high exhaust gas temperatures, or abrasive particles.
• Oil leakage from bearing housing seals (labyrinth or mechanical) into the compressor or turbine side, indicating seal wear or improper sealing air pressure.
• Excessive vibration due to rotor imbalance (fouling, damage), bearing wear, or misalignment.
• Cracks in turbine or compressor casings, often near high-stress areas or due to thermal cycling and vibration.
• Exhaust gas leakage from casing joints or expansion bellows, reducing efficiency and posing a safety hazard.
• Malfunction of speed sensor or overspeed trip mechanism, compromising safety.

Inspection checklist

• Visual inspection for oil leaks (especially around bearing housing and air/gas ducts) and exhaust gas leaks (casing joints, expansion bellows).
• Check for abnormal noise (whining, grinding) or excessive vibration during operation. Use a vibration meter if available.
• Measure axial and radial bearing clearances (rotor float) when the turbocharger is stopped and cooled. Compare with manufacturer's limits.
• Inspect compressor wheel and diffuser for fouling, erosion, or physical damage (e.g., blade bending, cracks).
• Inspect turbine blades and nozzle ring for fouling, erosion, cracks, or foreign object damage (FOD).
• Check the condition of the air intake filter element; ensure it is clean and properly seated.
• Verify lubricating oil pressure and temperature at the turbocharger inlet, and check oil filter condition.
• Confirm proper operation and pressure of the sealing air system to prevent oil ingress into gas/air streams.
• Inspect casing bolts for tightness and look for any signs of cracks or deformation on the casings.

Service intervals

Typical wear limits

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

Critical spares

• Complete bearing cartridge assembly (journal and thrust bearings)
• Oil seals and O-rings set for bearing housing
• Nozzle ring segments or complete nozzle ring
• Compressor wheel nut and locking washer
• Air filter elements (if applicable for specific intake design)
• Speed sensor (magnetic pick-up or inductive type)
• Gasket sets for casing joints and service covers
• Lubricating oil pump (if external and critical for operation)

Safety

• High rotational speeds (up to 20,000-30,000 RPM for this size) pose a rotor burst risk if overspeed occurs or significant imbalance/damage is present.
• Extremely high exhaust gas temperatures (300-600°C) on the turbine side, requiring proper insulation and caution to prevent burns.
• Pressurized systems (exhaust gas, charge air, lubricating oil, sealing air) can cause injury if opened improperly or if leaks occur.
• Hot lubricating oil under pressure can spray and cause severe burns or fire hazards.
• High noise levels during operation necessitate hearing protection in the vicinity of the turbocharger.

Class survey

Class surveyors typically focus on verifying the turbocharger's operational integrity and compliance with maintenance schedules. This includes reviewing the engine logbook for recorded operating hours, maintenance entries, and any reported defects or repairs. A visual inspection will be conducted for external leaks (oil, exhaust gas), signs of overheating, excessive vibration, and general condition. Surveyors will often request to see records of bearing clearance measurements, overspeed trip tests, and confirmation of critical spare parts availability onboard. If the turbocharger has been opened for maintenance, the surveyor may request to witness the reassembly or inspect internal components (e.g., bearing condition, rotor cleanliness) if deemed necessary based on the maintenance history or observed condition.

Estimated lifetime: Approximately 80,000 to 120,000 hours for main components (casings, rotor shaft) with regular maintenance, scheduled overhauls, and replacement of wear parts (bearings, seals, nozzle ring, etc.). The rotor assembly itself is designed for the engine's lifetime, provided it is not subjected to severe damage or neglect.