MET-MA 66MA

Common issues

• Bearing wear (journal and thrust) leading to excessive clearances, vibration, and potential rotor damage.
• Compressor fouling, reducing air flow efficiency, increasing exhaust gas temperature, and potentially leading to surge.
• Turbine fouling or blade damage (erosion, corrosion, or foreign object damage - FOD), causing reduced efficiency and increased exhaust back pressure.
• Oil leaks from bearing housings, often due to worn seals or excessive bearing clearances, posing a fire hazard and environmental concern.
• Excessive vibration, indicating rotor imbalance, bearing degradation, or internal rubbing, which can lead to structural fatigue.
• Exhaust gas leaks from casing joints, expansion bellows, or manifold connections, reducing efficiency and posing a burn hazard.
• Overspeed trip malfunction, a critical safety device failure that can lead to catastrophic turbocharger disintegration.
• Casing cracks, particularly in the hot gas path, due to thermal cycling, material fatigue, or excessive vibration.

Inspection checklist

• General condition and cleanliness: Inspect for oil, exhaust gas, or water leaks, corrosion, and overall integrity of external components.
• Rotor free rotation and axial/radial play: Manually check for smooth rotation without rubbing; measure axial and radial clearances if suspicious or during planned maintenance.
• Bearing lube oil system: Verify correct oil pressure and temperature, check filter condition, and review recent lube oil analysis reports for abnormal wear metals.
• Compressor and turbine blades: Visually inspect for fouling, erosion, corrosion, foreign object damage (FOD), and evidence of tip rub.
• Nozzle ring and diffuser: Check for fouling, cracks, distortion, and any signs of damage that could impede gas flow.
• Air filter condition: Ensure the air intake filter is clean, intact, and properly seated to prevent FOD and maintain optimal air supply.
• Exhaust gas casing and insulation: Inspect for cracks, hot spots, and the integrity of thermal insulation to prevent heat loss and burn hazards.
• Safety devices: Verify the functionality of the overspeed trip mechanism (via test records) and other alarm functions (e.g., high vibration, low oil pressure).
• Vibration monitoring: Review current vibration levels against baseline data and alarm limits to detect early signs of imbalance or bearing issues.

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 set (journal bearings, thrust pads, and associated seals).
• Full gasket and O-ring kit for major overhaul and sealing critical interfaces.
• Lube oil filter elements (primary and secondary).
• Overspeed trip sensor and/or actuator.
• High-tensile bolts and nuts for casing joints (especially if reusable limits are reached).
• Compressor washing nozzles (if specific to the model and prone to clogging/damage).

Safety

• Overspeed and disintegration: The turbocharger rotor operates at extremely high speeds (up to 15,000-20,000 RPM for this size), posing a catastrophic failure risk if overspeed protection fails.
• Hot surfaces: Exhaust gas casings and turbine components operate at very high temperatures (300-600°C), presenting a severe burn hazard if insulation is compromised.
• High-pressure exhaust gas leaks: Leaks can cause severe burns, hearing damage, and create a hazardous atmosphere in the engine room.
• Noise: The turbocharger generates extremely high noise levels during operation, necessitating hearing protection for personnel in the vicinity.
• Lube oil leaks: Leaking hot lubricating oil onto hot surfaces (e.g., exhaust manifold) poses a significant fire hazard.

Class survey

Class surveyors typically focus on: Review of maintenance records, running hours, overspeed trip test reports, and lube oil analysis. External inspection for general condition, cleanliness, and absence of oil, gas, or water leaks. Verification of safety device functionality (overspeed trip, alarms) and proper insulation on hot surfaces. Assessment of vibration monitoring data. Indirect assessment of bearing condition via oil analysis. Inspection of air intake filter and exhaust gas system integrity (e.g., expansion bellows).