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Implementing Your Engine Condition Monitoring System

Understanding the Importance of Engine Condition Monitoring.

We will explore the importance of an engine condition monitoring system for your aircraft. We’ll discuss why it’s a fundamental aspect of proactive and responsible aircraft ownership and guide you through the implementation process. From selecting a reliable maintenance shop to understanding the different components of the system such as engine monitor data analysis, borescope inspections, and oil analysis, we’ve got you covered. Let’s dive into how you can ensure the health and longevity of your aircraft engine.

Establishing the Basics For Effective Engine Condition Monitoring

Before you start implementing an engine condition monitoring system, it’s important to lay down some groundwork. As an aircraft owner, this involves selecting a reliable maintenance shop or mechanic, choosing the components that you want to run on-condition, and defining the maintenance tasks you intend to perform.

These ground rules should cover important aspects like airworthiness reviews, routine and non-routine maintenance, and troubleshooting procedures. A fundamental principle here should be insisting on a written estimate before any maintenance work starts. Furthermore, having continuous communication during the maintenance process ensures you approve any tasks and are informed of all new developments. A crucial part of these ground rules should be the incorporation of your engine condition monitoring system.

Recognising the Importance of Engine Condition Monitoring

Implementing an engine condition monitoring system is not just an optional addition to your aircraft maintenance routine. It is a vital component that helps maintain and prolong the life of your engine. Despite its importance, engine condition monitoring can sometimes be overlooked or undervalued. Regular inspections and analyses should form the backbone of your maintenance schedule to keep track of your engine’s health over time.

A comprehensive engine condition monitoring system should include the following key components:

    1. Engine Monitor Data Analysis
    2. Borescope Inspections
    3. Oil Analysis
      • Oil Filter Inspection
      • Dry Particle Analysis/Scanning Electron Microscope (SEM)
      • Spectrographic Oil Analysis

Engine Monitor Data Analysis: A Close Watch on Your Engine's Performance

Engine monitor data analysis is essential for tracking your engine’s performance over time. If you haven’t already invested in an engine monitor unit, now is the perfect time to do so. These units, along with GAMIjector® fuel injectors and TurboGAMIjector® fuel injectors, can essentially pay for themselves over time by optimising flight operations, maintenance, and troubleshooting processes.

Regularly downloading and reviewing your engine monitor data can provide detailed insights into your engine’s health and performance. Early warning signs, such as a failing exhaust valve, can be detected and rectified before they escalate into more serious problems.

Borescope Inspections: A Non-Invasive Method to Check Your Engine's Health

Borescope inspections are a cost-efficient and valuable tool in the engine condition monitoring toolkit. They provide a view inside your engine, allowing for regular checks of your valves, piston crowns, and cylinders. This continuous record can help identify potential issues, such as burned exhaust valves, before they become critical problems.

Oil Analysis: A Critical Part of Your Engine's Health Check

The practice of oil analysis is a key aspect of any engine condition monitoring system. However, this process is often overlooked or misunderstood, leading to inconsistent or incomplete checks. It’s vital to perform a thorough oil analysis at each oil change. Let’s delve into the integral parts of oil analysis.

A First Line of Defence: Oil Screen Inspection

Inspecting the oil suction screen or draining the oil through a strainer during every oil change serves as the first line of defence in the oil analysis process. Large particles or metal flakes, which could be early signs of an impending issue, are often identified during this stage.

Unseen Clues: Oil Filter Inspection

Oil filter inspections are a crucial part of the engine condition monitoring process. It’s advisable to incorporate a full-flow filter if your engine isn’t equipped with one. Oil filter inspections serve as a key tool in identifying tiny particles that may signify an upcoming or potential problem.

Recognising Metal Particles

    • Carbon. Black, shiny particles resulting from excessive hot oil that’s coking.
    • Steel. Silver-coloured and ferrous particles that are magnetic. A significant amount of these particles could indicate excessive wear or a malfunctioning component, often caused by corrosion.
    • Aluminium. Silver-coloured non-ferrous particles that dissolve when exposed to a dilute solution of dye. These particles may originate from scuffing piston pin plugs, fretting crankcase halves, loose valve guides, or damaged pistons.
    • Chrome. Shiny, sharp flakes that are much harder than aluminum. Any amount of chrome is abnormal, except during break-in. Chrome flakes can originate from chrome-plated piston rings, cylinder barrels, or exhaust valve stems.
    • Brass/Copper/Bronze. Yellow-coloured particles that may come from bushings, aluminium/bronze valve guides, or the starter adapter spring in Continental engines.

Decoding Metal Particles: Dry Particle Analysis/Scanning Electron Microscope (SEM)

If a substantial amount of metal is found during the oil screen or filter inspections, sending the sample for dry particle analysis using a scanning electron microscope (SEM) could be highly beneficial. The SEM provides a detailed view of the particles, allowing for precise identification and understanding of their origin and potential implications.

A Detailed View: Spectrographic Oil Analysis

Spectrographic oil analysis (SOA) is a preventive measure that involves sending an oil sample to a laboratory following every oil change. It offers a detailed breakdown of microscopic particles in the oil, which can unveil potential wear trends and engine abnormalities. For instance, elevated levels of iron could signal cylinder wear, while high amounts of aluminium might indicate piston issues.

Additional Elements in Oil Analysis

Some laboratories do not only analyse the oil for metals but also check for insolubles, viscosity, and water content. These factors can indicate insufficient filtration by the oil filter, oil contamination or excessively high oil temperatures, and inadequate operation of the aircraft engine.

Maximising the Benefits of Oil Analysis

To get the most out of the oil analysis, follow these tips:

    1. Consistently perform the oil analysis during each oil change.
    2. Choose a laboratory and stick to it for all your samples to minimise variations and maintain consistent results.
    3. Whenever possible, use the same flight hours interval for consistent results and keep it in mind when you have an outlier in flight hours.
    4. Use the same engine oil.
    5. Apply the same procedure for sampling the oil probe – ideally immediately after landing when the engine and oil are still hot and particles have not settled yet, and midway as the oil is being drained from the engine.

Both oil screen and filter inspection and spectrographic oil analysis are critical tools for monitoring the health of your aircraft’s engine(s). Don’t overlook them!


Implementing a detailed engine condition monitoring system for your aircraft is a fundamental step toward responsible and proactive ownership. This system allows for early detection of potential problems, reducing the risk of significant damage and unexpected repair costs. It’s not enough to perform inspections in isolation. A comprehensive and consistent approach to monitor your aircraft engine’s condition over time is essential. By establishing this system and working with a reliable maintenance shop, you can ensure the health and longevity of your aircraft engine. This proactive approach to engine care can not only provide peace of mind but also enhance your aircraft’s performance and lifespan.

About Quest Aeronautics

Quest Aeronautics is a state-certified engineering office for aviation, dedicated to shaping the future of general aviation by providing innovative and cost-effective solutions to enhance aircraft performance and operations. With a focus on CS/FAR-23 and experimental/amateur-built (E/A-B) aircraft, Quest Aeronautics provides a range of services including flight testing, aircraft operations and maintenance consulting, high-quality aviation products, and tailored support for E/A-B projects. Collaborating with industry-leading partners, Quest Aeronautics is committed to delivering unparalleled support and expertise to individuals and organisations in the general aviation market.

About Author

Sebastian, the founder of Quest Aeronautics, is a driven and enthusiastic individual with a passion for aviation. Before delving into aviation, he gained valuable experience as a chemical process engineer and laboratory technician. Sebastian holds a Master of Science in Engineering and a commercial pilot licence, with several fixed-wing aircraft ratings under his belt. He has also completed an introduction course for fixed-wing performance and flying qualities flight testing at the National Test Pilot School in Mojave, CA and is compliance verification engineer for flight.