Section 12 Planned maintenance and condition monitoring procedures, and ‘upkeep by exchange’

12.1 Planned maintenance approach

12.1.1 Suitable gas turbine package, Planned Maintenance and Condition Monitoring Schemes (PMS(CM)), will be accepted as part of LR’s Continuous Survey Machinery (CSM) cycle, provided the principles defined in Vol 2, Pt 2, Ch 2, 12.2 Preventive maintenance are satisfied.

12.2 Preventive maintenance

12.2.1 Preventive maintenance requires items to be opened for inspection by removing inspection covers or partial disassembly as appropriate, by using probes or by direct observation, and overhaul at specified time periods or after a specified number of running hours.

12.2.2 Maintenance is normally carried out irrespective of the condition of the gas turbine package components in order to retain the package in a satisfactory operational condition.

12.3 Unscheduled maintenance

12.3.1 The planned maintenance scheme is to be capable of dealing effectively with breakdown or corrective maintenance, i.e. unscheduled maintenance.

12.4 Condition monitoring

12.4.1 The conditioning monitoring techniques to support the trend away from preventive maintenance, are listed in Table 2.12.1 Condition monitoring techniques. They are considered the minimum acceptable to obviate the need for a fully opened out inspection of engine components at Periodical Survey.

Table 2.12.1 Condition monitoring techniques

Method	Requirement
Visual inspection	Periodic inspection of intakes and exhaust ducts, inlet guide vanes, compressor 1st stage, compressor and gas generator casings and auxiliary components and systems. The running clearances and dimensional changes, where practicable
Visual inspection by borescope/endoscope	Periodic inspection of compressor stators, guide vanes and blades, combustion chambers, turbine nozzles and blades and power turbine
Vibration monitoring	Continuous monitoring and trend analysis of gas generator and power turbine rotor vibration. The equipment used for vibration measurement should be capable of determining vibration throughout the operating range of the gas turbine
Lubrication, oil trend analysis programme	Periodic inspection of magnetic particle detectors (manual records and/or automatic recording via debris counters in oil scavenge lines) Periodic inspection of oil filters Periodic sampling and laboratory analysis of lubricant quality
Fuel quality	Maintenance of fuel oil bunker/marine gas oil analysis records Periodic sampling and laboratory analysis of fuel quality
Performance monitoring	Continuous monitoring and trend analysis of critical gas turbine operating parameters including: Compressor conditions (inlet and exit temperature, delivery pressure and speed) Power turbine (inlet entry temperature and speed) Engine breather temperature Low cycle fatigue counter See Note
Note Manual recording and trend analysis methods may also be acceptable.

12.4.2 Alternative arrangements to those in Table 2.12.1 Condition monitoring techniques, which provide an equivalent level of confidence in the condition of the gas turbine package, will be considered.

12.5 ‘Upkeep by exchange’

12.5.1 Where the gas turbine is maintained using an ‘upkeep by exchange’ policy, the requirements in Vol 2, Pt 1, Ch 1, 6.10 Upkeep by exchange are to be satisfied. Details of the arrangements by which the gas turbine unit is to be exchanged are to be submitted to LR for approval.