Case Study – Data logging improves overhaul accuracy
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Case Study – Data logging improves overhaul accuracy

Metro Trains Melbourne (MTM) Comeng fleet had been in service for 25 years and been plagued with a wide range of issues that seemingly could not be addressed. Some of these were assumed to be insufficient cooling capacity, high temperatures causing high-pressure faults and compressor unreliability. The installation of data loggers was crucial to accurately understand the root cause of issues. An additional benefit of this type of work is that the data logging improves overhaul accuracy.

The Coachair solution:

Working with MTM following a review of the in-service fault information, it was determined to install data loggers on selected trains. The data collection period was over a single summer season and directly prior to the scheduled overhaul of the fleet.

The successful project allowed MTM and Coachair to accurately understand the true nature of the issues affecting the fleet. Coachair’s technical expertise determined the major findings including:

  • Out of temperature faults (No Fault Found)
    • Units were with not operating in cooling (relay failure external to HVAC) or running at reduced capacity without faulting.
  • Low supply airflow
    • Reduced cooling performance as a result of low airflow from undersized and dirty filters
  • Pressure fault
    • Poor design of a combined HP and LP switch meant pressure trips couldn’t distinguish if cause was high pressure or low pressure. Data logging identified the root cause was not HP and actually a LP fault even on a hot day.
  • Compressor reliability
    • Data logging identified that the compressor was subject to conditions of low airflow and poor pressure management causing its failure.

The invaluable information from the data loggers gave surety on diagnosis but helped with detailing a successful scope for the overhauls – the data logging improves overhaul accuracy.

Accurate information for servicing helped to reduce in-service failures and helps reduce servicing costs. To discuss how data logging might assist with your overhauls, contact us today.

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