New Framework for 12-Year Engine Rule

South Africa has finalised the regulatory framework providing an on-condition alternative for eligible privately operated Part 91 aircraft fitted with Textron Lycoming or Teledyne Continental engines that have reached their applicable time or calendar Time Between Overhaul (TBO) limitations.

The Thirty-Sixth Amendment of the Civil Aviation Regulations, 2026 was published under Government Notice 7845 in Government Gazette No. 55226 on 21 August 2026. The amendment includes changes to Parts 43 and 91 and came into operation upon publication.

The South African Civil Aviation Authority (SACAA) has also approved SA-CATS 4 of 2026, which inserts Appendix 3 into SA-CATS 43 and establishes the detailed Condition Monitoring Programme (CMP) framework.

Appendix 3 states that its objective is to support continued safe operation beyond a manufacturer’s recommended time or calendar TBO through documented condition monitoring, until the engine’s condition indicates that it should be withdrawn from service.

The change addresses the issue commonly referred to within South African General Aviation as the “12-year engine rule”, but it does not simply remove overhaul requirements. Instead, eligible engines may be operated on condition through a documented CMP.

Who the New Framework Applies To

The framework is intended for eligible aircraft operated privately under Part 91.

SACAA’s accompanying General Notice specifically applies to Aircraft Maintenance Organisations (AMOs) approved to maintain and certify Textron Lycoming or Teledyne Continental piston engines, as well as owners and operators of aircraft fitted with those engines.

The CMP provisions may not be used for commercial air transport, flight training or other commercial operations.

Appendix 3 covers privately operated, type-certificated aeroplanes with a maximum certificated mass not exceeding 5,700 kg and rotorcraft not exceeding 3,175 kg.

The new provisions should therefore not be interpreted as a general relaxation of TBO requirements across all engine manufacturers or aircraft operations.

How an Engine Enters the Programme

An owner electing to operate an eligible engine on condition must formally adopt and sign a CMP.

The aircraft’s maintenance documentation must incorporate the programme, while its Aircraft Maintenance Programme must reflect the condition-monitoring methodology being applied.

An appropriately rated Part 145 AMO must perform or supervise the inspections and maintenance carried out under the CMP and remains responsible for the applicable maintenance certification.

Before an engine enters the programme, Appendix 3 requires a documented engine history. This includes relevant engine logbooks, recent leak-down or blow-by results, oil-consumption records, previous overhaul records and applicable Airworthiness Directive and Service Bulletin records.

The AMO must then conduct a baseline condition assessment to establish the engine’s general serviceability.

The assessment includes, as applicable, oil and filter inspection and analysis, internal engine inspection using a borescope, cylinder leak-down or blow-by assessment, ignition and fuel-system checks and an assessment of the engine’s general mechanical and operational condition.

If the baseline assessment identifies a condition that renders the engine unserviceable, that condition must be rectified before the engine can enter the CMP.

Continued Operation Depends on Condition

Entering the CMP does not mean an engine may simply continue operating indefinitely.

Following the initial baseline assessment, continued inspections are required at the applicable inspection or oil-change intervals for the first 12 months or 100 hours, whichever occurs first.

If the engine’s condition remains stable during this period, it may thereafter revert to the normal inspection, maintenance and Mandatory Periodic Inspection routines applicable to the aircraft.

Monitoring under Appendix 3 is based on engine condition and trends rather than one measurement in isolation.

The programme considers factors including oil and filter findings, oil analysis, cylinder condition, borescope findings, vibration, oil consumption, metallic debris, extended inactivity and corrosion.

Appendix 3 uses a Green, Amber and Red escalation system.

A Green condition means the monitored parameters remain stable and continued operation is permitted.

An Amber condition indicates an emerging adverse trend. Further investigation is required, and continued operation may be permitted with increased monitoring or defined limitations, depending on the AMO’s assessment.

A Red condition indicates that the engine presents an unacceptable risk to continued safe operation. The aircraft must then be grounded until the condition has been investigated, rectified and serviceability restored.

A single Amber finding does not automatically require grounding. Likewise, Appendix 3 makes clear that decisions should be based on condition, severity, progression and corroborating indicators rather than simply counting individual Amber events.

Aircraft Must Be Identified as Operating on Condition

Aircraft operating an engine under the CMP must also carry a clearly visible and legible sign stating:

“THIS AIRCRAFT ENGINE IS OPERATED ON CONDITION”

The sign may be positioned on the exterior or interior of the aircraft, but must be readily visible to passengers.

Following an applicable maintenance inspection or condition review, the AMO must also record in the engine logbook that the engine has been assessed in accordance with the CMP and, based on the findings at that time, is considered satisfactory for continued operation on condition.

That statement is valid only until the next scheduled inspection or condition review, or until an adverse trend triggers earlier escalation.

Provision for Aircraft Already Affected

SACAA’s General Notice also provides a transitional arrangement for some aircraft directly affected by the earlier 12-year TBO issue.

Where an aircraft’s Certificate of Airworthiness expired on or after 26 November 2024, but before the CMP provisions took effect, and it can be demonstrated that the certificate was not renewed directly because of the 12-year TBO matter, SACAA may conduct a desktop review rather than a physical inspection as part of the Certificate of Airworthiness process.

This is not automatic.

SACAA retains the right to require a physical inspection where the submitted documentation is insufficient, compliance cannot satisfactorily be established through a desktop review, or an inspection is otherwise considered necessary in the interests of aviation safety.

The Authority also makes clear that adoption of a CMP does not remove any other continuing-airworthiness requirements.

This includes applicable Original Equipment Manufacturer storage and preservation requirements where an engine has been inactive for an extended period.

For affected owners, the regulatory position has therefore moved beyond simply reaching a calendar or hourly TBO limit. Eligible Lycoming- and Continental-powered private aircraft now have a defined on-condition route, but continued operation depends on documented engine condition, a properly adopted CMP and maintenance oversight by an appropriately rated AMO.

Key Points

• Who does this apply to? Eligible privately operated Part 91 aircraft fitted with Textron Lycoming or Teledyne Continental engines.
• What has changed? Reaching the applicable time or calendar TBO no longer necessarily means that an eligible engine must immediately be overhauled. A formal on-condition route is now available.
• Does this mean the 12-year rule has simply disappeared? No. Continued operation is subject to the requirements of the Condition Monitoring Programme.
• Can commercial or training aircraft use the CMP? No. SACAA states that the provisions are for private Part 91 operations only.
• What must the owner do? The owner must formally adopt and sign the CMP and ensure that the aircraft’s maintenance documentation reflects the programme.
• What must the AMO do? An appropriately rated AMO must assess the engine before entry, perform or supervise the required inspections and maintenance, and make the applicable maintenance and release-to-service records.
• What happens before an engine enters the CMP? Its history must be reviewed and a baseline condition assessment completed, including applicable oil, filter, borescope, cylinder, ignition, fuel-system and general mechanical checks.
• What happens after entry? The engine is monitored at the applicable inspection or oil-change intervals for the first 12 months or 100 hours, whichever occurs first. If its condition remains stable, normal inspection routines may then resume.
• What if a problem develops? Green permits continued operation, Amber requires further investigation and potentially closer monitoring, while Red requires grounding until the problem has been rectified.
• Does the aircraft need to be marked? Yes. An aircraft operating an engine on condition must display a visible notice stating: “THIS AIRCRAFT ENGINE IS OPERATED ON CONDITION.”
• What about aircraft already caught by the earlier 12-year issue? Certain aircraft whose Certificates of Airworthiness expired on or after 26 November 2024 because of the 12-year TBO matter may qualify for SACAA’s transitional desktop-review process, subject to the required documentation and SACAA’s assessment.