LM6000series Engine Condition and Trend Monitoring
Performance Chart Description & Analysis

IAAS Australia Pty Ltd proudly presents: HawkEye® Engine Condition & Trend Monitoring.

The LM6000 Performance Trend Monitoring Program enables trends in engine parameters to be monitored at various engine MW loads. This powerful new program offers predictive failure analysis and aides in preventative maintenance, performance and deterioration analysis and maintenance forecasting.

LM6000 Engine Condition and Trend Monitoring charts have been developed using;

• Recorded data tabulated against the MW load.
• The table of data was sorted in order of decreasing MW.
• Charts were plotted of each parameter against MW
• A trend line was applied to each chart.
• An equation was applied defining the trend line for each parameter. This equation was then used to define a base value for each parameter against any specific MW load.
• The difference between the actual recorded parameter, corrected for T25, and the calculated base value is termed the delta parameter value and is plotted on the trend charts against the date the data was recorded.

The results of this process are trend charts with reduced data scatter where trends are more readily identifiable. These charts now closely resemble the type of charts used in monitoring performance trends in the aerospace application.

Parameters selected for charting are continuously revised, as part of the continuing process to refine and improve the LM6000 Performance Trend monitoring Program. Following is a description of the parameters now selected for trend monitoring along with the reason for selecting them and how they inter relate:

Delta MW

The Delta MW Output chart represents the variation in MW output Vs T48 compared to baseline and reflects the trend in maximum MW output at maximum T48.

T48.LPT Inlet Temperature

All forms of engine gas path deterioration will be evident as an increase in T48 (at constant engine power output). A corresponding shift up or down in other parameters will confirm the deterioration and assist in identifying the cause.

HP Rotor RPM

Engine performance deterioration will generally result in either an upward or downward shift in HP rotor RPM. If the deterioration is in the HP Turbine the HP RPM will generally decrease. If the deterioration is in the Compressor the RPM will generally increase. The RPM will also increase if there is leakage of compressor air. All shifts in RPM will be accompanied by increasing T48.

HP Compressor Ratio (HPC discharge Pressure / HPC Inlet Pressure).

Compressor efficiency is indicated by the relationship between HP Compressor Ratio and HP RPM. A downward trend in compressor ratio Vs HP RPM indicates compressor deterioration or leakage of compressor air.

P25 HPC Inlet Pressure (LPC Outlet Pressure)

Under near maximum engine output, corrected P25 should be reasonably constant since LP RPM is constant and VBV’s closed.

HP RPM (N25) / HPC Compressor Ratio (Ps3/P25) (HP Compressor Efficiency)

As the compressor becomes less efficient for example due to salt and dirt deposits from the atmosphere, the pressure ratio will decrease and the speed will increase resulting in an increase in the ratio of speed to compressor ratio.

Engine Pressure Ratio (EPR) (Pt48/P0) (Engine Power)

Assists in identification of those areas of the engine responsible for performance deterioration indicated in the trends of other parameters.

Core Engine Pressure Ratio (Pt48/P25)

Assists in identification of those areas of the engine responsible for performance deterioration indicated in the trends of other parameters.

Compressor Discharge Pressure / HP Turbine Discharge Pressure (Ps32 / Pt48)

Assists in identification of those areas of the engine responsible for performance deterioration indicated in the trends of other parameters.

Turbine Vibration

Changes in vibration profiles either up or down can indicate a problem that requires further investigation.