WearCheck has been helping to safeguard aircraft engine reliability through advanced condition monitoring and oil analysis for more than five decades. The company's experienced team of chemists, diagnosticians and technicians has analysed thousands of aircraft engine oil samples, providing valuable insights into engine health and supporting safe, efficient operations.
WearCheck's aviation consultant, Daan Burger, who served as a company diagnostician for more than 30 years, welcomes the recently proposed amendments to South Africa's aircraft maintenance regulations and explains how the changes will benefit aircraft owners, operators and passengers:
The long-anticipated shift in South African aviation maintenance philosophy has cleared its most significant regulatory hurdle. Following approval by the South African Civil Aviation Authority's Civil Aviation Regulations Committee (CARCom), the amendment to SA-CATS 43 introducing Appendix 3, a formalised Condition Monitoring Programme (CMP), now awaits final promulgation by the Minister of Transport.
Often referred to as the "12-year rule", this long-standing overhaul requirement has been one of the most debated issues in South African general aviation. Once promulgated, the new framework will replace fixed calendar or hour-based limits with a structured, evidence-based approach that allows engine condition, not simply age, to determine continued serviceability.
For decades, piston-engine aircraft maintenance has largely followed a rigid philosophy: overhaul at fixed time intervals, regardless of actual engine condition. While this approach has ensured conservative safety margins, it has also placed significant financial and operational strain on private aircraft owners.
The amendment represents a meaningful evolution. It allows privately operated, type-certificated piston aircraft to operate beyond manufacturer-recommended time between overhaul (TBO), provided that engine condition can be demonstrated as satisfactory through structured, evidence-based condition monitoring.
At its core, this is more than a regulatory amendment – it is a shift toward data-driven maintenance, where decisions are based not on assumptions, but on actual engine behaviour, performance trends and condition indicators.
From Time-Based to Condition-Based Maintenance
The amendment introduces Appendix 3 to SA-CATS 43, establishing a framework where maintenance decisions are no longer based purely on hours or calendar limits, but on actual engine condition and performance trends.
This represents a significant evolution in maintenance philosophy. Instead of assuming that all engines degrade at the same rate, the CMP recognises that operating conditions vary widely, utilisation patterns differ and, as a result, engine-wear is not linear.
Under this framework, continued operation beyond TBO is permitted until the engine condition indicates that withdrawal from service is necessary, rather than when a fixed limit is reached.
However, this flexibility comes with responsibility.
The regulation does not simply extend engine life - it extends the opportunity to demonstrate continued airworthiness through objective, evidence-based condition monitoring.
Structured Monitoring: The Cornerstone of the CMP
The CMP is not a relaxation of standards. Rather it is a structured, evidence-based system that requires disciplined monitoring and record keeping.
Key elements include:
• Oil-filter inspections at every oil change
• Spectrographic oil analysis
• Borescope inspections
• Leak-down or blow-by testing
• Continuous operational monitoring by the pilot
Importantly, no single parameter is used in isolation. Decisions must be based on trends, correlations and the overall picture of engine health.
This is a critical point. Condition-based maintenance is only as reliable as the quality, consistency and interpretation of the data supporting it.
Why Oil and Filter Analysis Matter More Than Ever
Among the monitoring tools specified, oil and filter analysis stand out as particularly practical and powerful for piston-aircraft operators.
Engine oil is far more than just a lubricant – it is a carrier of information, continuously transporting wear metals, contaminants and degradation by-products from internal components.
Oil and filter analysis provide direct insight into engine condition, allowing operators to:
• Detect abnormal wear at an early stage
• Identify contamination (fuel, water, dust and lead by-products)
• Monitor oil degradation (oxidation and viscosity changes)
• Track trends over time to identify emerging failures
• Confirm grade and type of oil in use
Crucially, oil analysis operates within the predictive maintenance domain by detecting issues during the P-F interval (the window between the onset of a defect and functional failure).
Filter analysis complements this by capturing larger wear particles that do not appear in standard spectrometric testing, providing additional insight into component distress.
Trend-Based Thinking: A Cultural Shift
One of the most important aspects of the CMP is its emphasis on trend analysis rather than single data points. Oil analysis results must be interpreted based on rate of change and historical behaviour, not absolute values alone.
This aligns directly with best practice in oil analysis, where meaningful diagnosis depends on:
• Consistent sampling intervals
• Repeatable sampling methods
• Historical data
• Expert interpretation
For aircraft owners, this represents a shift from reactive maintenance to informed decision-making.
Balancing Opportunity with Risk
The introduction of the CMP provides clear benefits, including reduced unnecessary overhauls, lower maintenance costs, improved asset utilisation and alignment with international best practice.
However, it also introduces a new level of accountability. Owners who elect to operate on condition must accept responsibility for airworthiness decisions, ensure compliance with the CMP, maintain accurate and complete records and work closely with Approved Maintenance Organisations (AMOs). In essence, the CMP replaces prescriptive rules with informed responsibility.
How WearCheck Supports Condition Monitoring
As condition-based maintenance becomes formalised in South African aviation, the role of specialised analysis services becomes increasingly critical.
WearCheck's aviation oil- and filter-analysis programme is specifically designed to support this approach by providing:
• Trend-based oil analysis with aviation-specific limits and interpretation
• Wear-particle identification to determine component sources
• Filter-debris analysis for detection of larger, potentially critical wear particles
• Integrated reporting combining oil condition, wear and contamination insights
Importantly, this approach aligns directly with the principles of the CMP through:
• Multi-parameter assessment
• Trend-focused diagnostics
• Correlation between oil, filter and operational data
This ensures that oil analysis supports maintenance decisions without ever replacing engineering judgement.
A Step Forward for South African General Aviation
The approval of Appendix 3 to SA-CATS 43 represents a significant milestone for South African aviation. Once promulgated, it will bring local regulation into closer alignment with international trends toward predictive and condition-based maintenance while maintaining a strong emphasis on safety and accountability.
For private aircraft owners, the opportunity is clear - move beyond rigid, time-based maintenance schedules and adopt a more intelligent, condition-driven approach. But this flexibility comes with responsibility. Success under a condition monitoring programme depends entirely on the quality, consistency and interpretation of the data that supports it.
Oil and filter analysis now play a more critical role than ever. No longer optional or supplementary, they form part of a structured decision-making framework, one that relies on trend analysis, the correlation of multiple condition indicators and informed engineering judgement.
As South Africa moves closer to implementing this new regulatory framework, the question is no longer whether engine condition should be monitored, but how effectively it is being monitored.
Working with experienced laboratories and implementing a disciplined, trend-based oil- and filter-analysis programme will be key to unlocking the full benefits of condition-based maintenance safely, confidently and cost effectively.
For more information on implementing a condition monitoring programme aligned with the forthcoming regulations, contact WearCheck to discuss how our aviation oil- and filter-analysis services can support your operation with reliable data, expert interpretation and informed maintenance decisions.
