Part-ML

The Regulations page for Regulation, Acceptable Means of Compliance (AMC) and Guidance Material (GM) provides further information.

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 CAA LAMP has been withdrawn.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.

The General Aviation Unit surveyors have been conducting various surveys of GA aircraft types and have identified a deteriorating trend with respect to lack of supervision of unlicenced persons by Part 66 Licenced Aircraft Engineers (LAE) who are issuing a Certificate to Release to Service under Part ML.A.801 for aircraft below 2730Kgs.

Any unlicenced persons must be continuously monitored and controlled and is suitably trained and competent to complete whatever the task which has been delegated to that person.

Any work completed by unlicenced persons is required to be inspected in sufficient depth to ensure the work is completed correctly in accordance with the specified maintenance data.

To ensure compliance to Part ML requirements the LAE must be onsite with the aircraft while work is performed. Remote supervision is not acceptable (this is either when working independently under your Part 66 Licence or as part of an approved organisation e.g. CAO).

Refer to Part ML.A.402(b) (and AMC ML.A.402(b)(7)) and ML.A.901(d) for full details.

The General Aviation Unit surveyors have been conducting various surveys of GA aircraft types and have identified confusion regarding when a B2 or B2L Part 66 Licenced Aircraft Engineer (LAE) is required to complete and certify work on a Avionic System. Part 66 provides flexibility to allow some avionic work to be certified by a B1, B3 or L Category LAE, however this is supposed to be ‘work on avionic systems requiring only simple tests to prove their serviceability and not requiring troubleshooting.’ Refer to Part 66.A.20 for further details.

GM 66.A.20(a) Privileges provides the definition of Avionic systems and Simple Tests which are:

Avionics system means an aircraft system that transfers, processes, displays or stores analogue or digital data using data lines, data buses, coaxial cables, wireless or other data transmission medium, and includes the system’s components and connectors.

Simple Test definition has three elements to it which all are required to be satisfied:

• The serviceability of the system can be verified using aircraft controls, switches, Built-in Test Equipment (BITE), Central Maintenance Computer (CMC) or external test equipment not involving special training.
• The outcome of the test is a unique go – no go indication or parameter, which can be a single value or a value within an interval tolerance. No interpretation of the test result or interdependence of different values is allowed.
• The test does not involve more than 10 actions as described in the approved maintenance data (not including those required to configure the aircraft prior to the test, i.e. jacking, flaps down, etc, or to return the aircraft to its initial configuration). Pushing a control, switch or button, and reading the corresponding outcome may be considered as a single step even if the maintenance data shows them separated.

Refer to the GM for further details.

Therefore, is clear that extensive disassembly or modification work on Avionic systems will require completion and certification by a B2 or B2L LAE. However simple tests and replacements which may stem from scheduled or non-scheduled activities especially where more modern external test equipment is available or systems have BITE available can be certified by B1, B3 or L LAE’s (this includes electromechanical and pitot-static instruments/components).

The General Aviation Unit surveyors have been conducting various surveys of GA aircraft types and have identified confusion regarding the extent of maintenance that can be performed by a ‘Pilot-Owner’  To ensure clarity this aspect of the regulation can only be used if the individual is both the OWNER of the aircraft AND holds a VALID TYPE RATED PILOT LICENCE. Additionally, it must NOT be OPERATED COMMECIALLY (e.g. DTO/ATO, SPO, AOC).

The pilot-owner shall comply with the following basic principles before it carries out any maintenance task:

Competence and responsibility

1. The pilot-owner shall always be responsible for any maintenance he/she performs.
2. The pilot-owner shall hold satisfactory level of competence to perform the task. It is the responsibility of a pilot-owner to familiarise themself with the standard maintenance practices for their aircraft and with the Approved Maintenance Programme (AMP).

After completion of any maintenance by the Pilot-Owner, they shall issue a Certificate of Release to Service (CRS) in accordance with Part ML.A.803 and shall be enter in the logbooks basic details of the maintenance carried out, the maintenance data used, the date on which that maintenance was completed, as well as the identity, the signature and the pilot licence (or equivalent) number of the pilot-owner issuing the CRS.

The pilot-owner must inform the contracted CAMO or CAO (if such contract exists) about the completion of the pilot-owner maintenance tasks no later than 30 days after completion of these tasks in accordance with point (a) of point ML.A.305.

Allowable Tasks

The Pilot-owner may carry out simple visual inspections or operations to check the airframe, engines, systems and components for general condition, obvious damage and normal operation.

Prohibited Tasks

A maintenance task shall NOT be completed/released by the pilot-owner if any of the following conditions occurs:

• it is a critical maintenance task (e.g. Flight Controls, Engines Controls);
• it requires the removal of major components or a major assembly (e.g. Engine Components, Engine removal, flight control removal, Landing Gear, door removal);
•  it is carried out in compliance with an Airworthiness Directive (AD) or an airworthiness limitation item (ALI) unless specifically allowed in the AD or the ALI;
• it requires the use of special tools or calibrated tools (except for torque wrench and crimping tool) (e.g. Tensiometer for flight control cables);
• it requires the use of test equipment or special testing (e.g. non- destructive testing (NDT), system tests or operational checks for avionics equipment such as Pitot-Static Tester);
• it is composed of any unscheduled special inspections (e.g. heavy- landing check, prop strike);
• it affects systems essential for the instrumental flight rules (IFR) operations (e.g. Pitot-Static Instruments, Attitude instruments, Vacuum system.);
• it is a complex maintenance task in accordance with Appendix III to Part ML, or
• it is a component maintenance task in accordance with point (a) or (b) of point ML.A.502;(9)
• it is part of the 100-h/annual check (for those cases the maintenance task is combined with the airworthiness review performed by maintenance organisations or independent certifying staff).