Engine Condition Trend Monitoring (ECTM) is defined as the use of engine operational data to find symptoms of damage, deterioration or excessive wear. Essentially, it is a technique that continuously monitors the health of your aircraft’s engines.
By tracking a known set of parameters (usually including altitude, outside air temperature, airspeed, interstage turbine temperature, N1/N2 rotations per minute (RPMs), fuel flow and vibrations), operators are better able to predict needed maintenance before a failure occurs. Knowing these parameters will not stop the initial problem from happening, but it is a great tool for predicting a failure before secondary damage can occur.
As an example, through ECTM an owner or operator may receive information indicating downward trends in performance and changes in the RPM that could lead to early hot section deterioration or suggest an engine or aircraft bleed leak. Sometimes the trend will point towards something very simple, such as the fact it’s time to do an engine water wash.
Who can do ECTM on Your Aircraft?
Properly trained, anyone could manually do the ECTM analysis, but operators should understand that the risk for error is high.
Many companies provide a subscription-based trending analysis service. These use computers and software to interpret the data, and as a part of the service provided operators will be notified of any anomalies that need addressing.
While some argue that the flight crews could notice the trends monitored by the ECTM service (and that certainly holds true for significant or sudden changes to performance), ECTM will identify subtle changes over a time period that a flight crew won’t notice.
That’s because aircraft tend to operate in different environmental conditions for every flight they make, causing it to be difficult for the flight crew to get a clear picture of the engines’ performance. However, the ECTM software can calculate the information you provide and correct it for standard day conditions, providing an apples-to-apples comparison of engine performance.
Does Engine Age Matter With ECTM?
Performing ECTM will always be a recommendation whether the engines and aircraft are old or new. Ultimately, an effective ECTM program consists of four parts:
- Capturing in-flight data
- Converting and comparing the data to mathematical models
- Detecting anomalies from the trend analysis, and
- Notification when anomalies exist.
For older aircraft operators, ‘Knee Board’ trending is one means of gathering and submitting the necessary information to the ECTM provider – Knee Board refers to the flight crew writing the required information down at a specific time during each flight.
Newer aircraft are capable of digitally recording this information on a storage device mounted on the engine or in the aircraft. A laptop computer is then used to download the information to a file format that can be emailed to the ECTM provider.
Modern engines are increasingly utilizing on-condition programs, where a teardown inspection of the engine for a Hot Section Inspection or even an overhaul is not performed. In order to participate in an on-condition program, ECTM is a requirement.
When Should You Start ECTM?
Although always advisable to perform ECTM, operators should start trending within the first 100 hours since new, just after a Hot Section Inspection, or an overhaul.
Having said that, some operators have started just before their engine went into the shop for overhaul, and that is also fine. The main point is to enroll and begin monitoring the trends.
Why? Because in the end, the cost of maintenance and the cost of each flight hour will be reduced…
More information from www.duncanaviation.aero