FT FT-23

Common issues

• Bearing wear (journal and thrust) leading to excessive rotor axial and radial play, often indicated by increased vibration or noise.
• Compressor and/or turbine fouling (carbon deposits, dust) reducing efficiency, causing surging, and increasing exhaust gas temperatures.
• Oil leakage from bearing housing seals (air side or gas side), leading to oil contamination in charge air or exhaust gas, and potential fire risk.
• Vibration due to rotor imbalance, bearing damage, or foreign object damage (FOD) to blades.
• Cracks in turbine casing, exhaust gas manifold connections, or nozzle ring due to thermal stress cycling.
• Surging, often caused by fouling, incorrect engine load, or issues with engine combustion.
• Foreign object damage (FOD) to compressor or turbine blades, leading to imbalance and potential catastrophic failure.
• Degradation of insulation on hot surfaces, increasing engine room temperatures and safety hazards.

Inspection checklist

• Monitor turbocharger RPM, boost pressure, and exhaust gas temperatures against engine load and manufacturer's data (daily logbook check).
• Check for abnormal noise or vibration during operation using a stethophone or vibration monitoring equipment.
• Inspect oil inlet and outlet lines for leaks, proper flow, and ensure oil drain is unobstructed.
• Perform rotor axial and radial play measurement (when stopped and cooled) using a dial gauge, comparing to manufacturer's limits.
• Visually inspect compressor and turbine blades for fouling, erosion, or FOD through inspection ports (if fitted) or by opening casing.
• Examine casing for cracks, loose bolts, signs of exhaust gas leakage, and condition of insulation.
• Check the condition of air filter elements and ensure proper sealing of the air intake system.
• Verify the functionality of compressor and turbine washing systems.
• Inspect the condition of the flexible bellows on the exhaust gas side for cracks or leaks.

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 (or individual journal and thrust bearings with associated seals).
• Complete gasket and O-ring set for overhaul.
• Air filter elements (multiple sets).
• Nozzle ring segments (if applicable and prone to wear/damage).
• Diffuser ring (if prone to damage or erosion).
• Seal rings (labyrinth seals) for both compressor and turbine sides.
• Specialized tools for disassembly and assembly (e.g., rotor lifting tools, bearing pullers).

Safety

• High Rotational Speeds: Rotor operates at extremely high RPMs; uncontained failure can lead to severe injury or structural damage.
• High Temperatures: Exhaust gas temperatures can exceed 500°C; all surfaces are extremely hot, posing severe burn risks. Ensure proper insulation and warning signs.
• High Pressure: Boost air pressure can be significant; ensure all connections are secure and pressure relief valves (if fitted) are functional.
• Confined Space Entry: Internal inspection or maintenance requires strict adherence to confined space entry procedures, including lockout/tagout, ventilation, and gas detection.
• Heavy Components: During overhaul, components like the rotor and casings are heavy and require appropriate lifting gear and safe handling procedures.

Class survey

Class surveyors typically focus on reviewing the turbocharger's maintenance history, including records of bearing replacements, major overhauls, and balancing reports. They will verify performance parameters (boost pressure, exhaust gas temperatures, RPM) against design specifications and recent logbook entries. A thorough external visual inspection for leaks, cracks, loose fastenings, and general condition is mandatory. If the unit has been opened for maintenance, the surveyor may request to witness the internal inspection of the rotor, bearings, nozzle ring, and diffuser. Confirmation of proper lubrication oil supply, drainage, and the condition of air intake filters and exhaust gas ducting is also critical. Any evidence of surging or abnormal operation will trigger further investigation.

Estimated lifetime: 48,000 - 72,000 hours before full rebuild (including rotor re-blading/replacement), with major overhauls (bearing/cartridge replacement) every 12,000 - 24,000 hours.