Part-ML provides a proportionate framework for continuing airworthiness to correspond to the lower risks associated with 'Light Aircraft' in general aviation.
Part-ML sets out requirements to ensure that 'Light Aircraft' remain airworthy and are in a condition for safe operation. It also establishes the responsibilities of persons and organisations involved in activities related to the continuing airworthiness of these aircraft.
Part-ML simplifies existing maintenance rules and offers a less prescriptive and burdensome approach to maintenance programmes, airworthiness reviews, defects deferments and TBO extensions. It also provides more privileges for pilots, owners, independent certifying staff and small maintenance organisations.
The Civil Aviation Authority (CAA) will no longer be involved in the approval of maintenance programmes for Light aircraft.
A new Airworthiness Review Certificate (ARC) (CAA Form 15c) has been introduced that can be issued by the CAA, by an approved organisation or by independent Part-66 engineers with an appropriate authorisation.
CAA Generic Requirements listed in Mandatory Requirements for Airworthiness (CAP747), have been revised to ensure their applicability does not contradict Part-ML. For example, GR No. 24 is no longer applicable to Part-21 aircraft, GR No. 11 remains mandatory for both Part 21 and non-Part 21 aircraft.
Definition of light aircraft under Part-ML
Light aircraft means the following non-complex motor-powered aircraft not listed in the air operator certificate of an air carrier licensed in accordance with UK Regulation (EC) No 1008/2008:
- aeroplanes of 2,730 kg maximum take-off mass (MTOM) or less.
- rotorcraft of 1,200 kg MTOM or less, certified for a maximum of up to 4 occupants.
- other ELA2 aircraft (for example sailplanes, balloons, small airships).
Independent Certifying Staff
- Part-ML introduces an independent certifying staff authorisation which allows licenced engineers to carry out the airworthiness review and issue the Airworthiness Review Certificate in conjunction with the annual inspection for light aircraft within the scope of Part-ML.
- The authorisation is issued after the applicant has carried out a satisfactory Airworthiness Review under supervision by the Civil Aviation Authority (CAA).
- The authorisation is limited by Part-ML and the scope of aircraft on the applicant’s licence.
- Existing ELA 1 authorisations are not valid after 24th March 2020 due to the change in regulations.
- Applications for an independent certifying staff authorisation should made using Form SRG1015 be submitted to email@example.com with 'ML.A.901 Authorisation' in the subject line.
Please use the downloadable Part-ML Aircraft Maintenance Programme (AMP) Issue 1 form.
Civil Aviation Authority (CAA) Light Aircraft Maintenance Programme (LAMP) cannot be used after 24 March 2021. CAA LAMP has been withdrawn. All aircraft within the scope of Part-ML must transfer to a Part-ML-compliant maintenance programme at the next Airworthiness Review.
GR No.17 and GR No.24 have been revised to remove their applicability to aircraft maintained under Part-ML.
Deviations from the Design Approval Holder's Instructions for Continuing Airworthiness (DAH ICA), such as the extension of time between overhaul (TBO) intervals, should be evaluated using a risk-based approach in accordance with ML.A.302.
The risk-based approach should consider aspects such as the operation of aircraft, type of aircraft, hours/years in service, maintenance of the aircraft, compensating measures, redundancy of components, etc.
Alternative tasks or intervals (for example, escalations) to the DAH ICA by the Continuing Airworthiness Management Organisation (CAMO) or Combined Airworthiness Organisation (CAO) do not need to be approved by the Civil Aviation Authority (CAA). Justification of these deviations are to be documented and retained by the CAMO or CAO.
Where an aircraft subject to Part-ML is not used for commercial operations and the owner elects to manage the continuing airworthiness of the aircraft themselves, the owner issues a declaration for the maintenance programme and in this case, no justification of such deviations is required.
Details can be found in Part-ML Paragraph ML.A.302 and AMC1 ML.A.302(c)(3). Owners, operators and approved organisations should ensure they are familiar with the revised regulations as well as the safety implications of any proposed deviations from the DAH ICA.
It is important to note that deviations with respect to tasks classified as mandatory (for example, Airworthiness Directives, requirements specified on the type certificate data sheet, airworthiness limitations) are not permitted.
Recent aircraft surveys by the Civil Aviation Authority (CAA) have highlighted the fact that servicing, overhaul and inspection of combustion heaters and their associated exhaust systems is not being included in the Aircraft Maintenance Programme (AMP).
These tasks must be carried out in be in accordance with the instructions contained in the appropriate manuals produced by the aircraft manufacturer and the equipment manufacturer. If the instructions in the aircraft manufacturer’s manual differ from those in the equipment manufacturer’s manual, those of the aircraft manufacturer shall be assumed to be overriding.
Mandatory Continued Airworthiness information from the state of design (for example, FAA AD’s) which may mandate additional tests and inspections must also be included in the AMP.
Additionally, Mandatory Requirements for Airworthiness (CAP 747), includes Generic Requirement GR No.11 which is mandatory for both Part 21 and non-Part 21 Aircraft on the UK register regardless of whether the AMP is approved by the CA(M)O or declared by the owner.