EASA Part-ML Maintenance

Changes and new possibilities in light aircraft maintenance for owner pilots

AMP Example Cover

Since March 2020, EASA Part-ML is in effect. The rules governing the maintenance of light airplanes are set into law and apply to all applicable airplanes bearing an EASA registration, no matter the national country. This article is meant as a brief overview to EASA Part-ML for a typical owner/pilot.

Finally, the days of inquiring “can I extend engine TBO in France” or “can I keep the prop on condition in Germany” are gone. The rules are harmonized throughout EASA member states, and they are seemingly more adequate for the operations and clientele they intend to regulate.

If so desired, the owner can elect to bear full responsibility for airworthiness, and with that comes more flexibility to maintain one’s airplane.

The following is applicable to privately owned and operated (according to EASA Part NCO) airplanes with a maximum weight not exceeding 2730kg. We’re talking of typical Single Engine Piston or Multi Engine Piston planes here.

Abbreviations:

  • AMP: Aircraft Maintenance Program
  • MIP: Minimum Inspection Program
  • DAH: Design Approval Holder (Manufacturer) 
  • AMM: Aircraft Maintenance Manual issued by DAH
  • CAMO: Cont. Airworthiness Management Organisation
  • CAO: Basically a CAMO, but with less authority requirements for it’s organisation (Safety Management etc..)
  • NCO: Non Commercial other than Complex (Private flights with SEP/MEP/SET planes)
  • TCDS: Type Certificate Data Sheet
  • AD: Airworthiness Directive
  • MX: Maintenance (sorry, airline pilot lingo)
  • TBO: Time before Overhaul (e.g. a recommendation to overhaul an engine, propeller or other part at a certain age or after a number of hours in operation)
  • On Condition: Never touch a running system, but rather inspect continuously and replace, overhaul etc.. only when broken.
A simplified step by step methodology to EASA Part-ML
  1. Declaration

The pilot owner declares (no approval required) the AMP for his airplane.

2. The Basis of the AMP

An AMP can be based either on
a) the MIP according EASA Part-ML 
or 
b) the AMM of the DAH 
or 
c) is not required at all if an owner follows all DAH instructions. In this case, one would declare that the airplane is maintained by observing all DAH AMM instructions (including engine/prop TBO limits). It is then not required to formulate an AMP.

3. Adapting the AMP

If option 2 a) or b) was elected, an AMP needs to be created. EASA published a handy template. Except for Airworthiness Limitations stated in the TCDS and/or the DAH AMM (usually found in chapter 4) as well as any ADs, the owner can deviate from the recommendations stated in the DAH AMM (usually found in chapter 5).

Example of Airworthiness Limitations in Chapter 4 of the DAH AMM (must be observed) [© Cirrus Design Corporation]
Examples of Time Limits in Chapter 5 of the DAH AMM (recommendations, deviations can be applied in the AMP) [© Cirrus Design Corporation]

These deviations cannot be less restrictive than the MIP though, and therefore “on condition” translates to inspecting the items at least every 100 hrs or annually, whichever occurs first.

Example:

The DAH AMM for the Cirrus SR22/SR22T states the following time limit (Note: this is not an airworthiness limit and legally only a recommendation, which is why you can deviate from it):
Task → Overhaul Engine 
Interval → 12 years/2000hours

Again, you can deviate from this DAH AMM time limit in your AMP to maintain the engine “on condition” by stating:
Task → Compression Test, Boroscope, Oil Filter Inspection et al..
Interval → 100 hours/12 months whichever earlier*.

*The 100 hours/12 months align the DAH AMM deviation of the individual AMP to the provision of “not being less restrictive than the MIP”. The MIP includes a blanket statement for all items that says:

To be performed at every annual/100-h interval, whichever comes first.

AMC1ML.A.302(d) Aircraft maintenance programme

4. Pilot Owner Maintenance – time to get your hands dirty, or not

A Pilot Owner now has extensive rights to perform and release his own maintenance actions. For instance, if the items for the 50hr check on your airplane are all covered by the EASA published list of Pilot Owner maintenance tasks, you can release the 50hr inspection yourself.

5. The ARC (Annual Inspection and Airworthiness Review Certificate)

The ARC can be extended by 

  • a Part 145 workshop (organisation) 
  • a CAMO/CAO (organisation, this doesn’t mean your airplane must be under a CAMO/CAO contract. It can, if you elect so – see 6.)
  • the Competent Authority (“national aviation authority”, organisation)
  • independent review staff (Part 66 with “ARC approval”, a person)

It’s important to note that, for obvious reasons, your AMP will be subject to review during the ARC extension as well. While the airworthiness review staff isn’t responsible for the AMP, they can elect to not extend the ARC if they deem it grossly negligent/inappropriate. My feeling is there can be a bit of a tear here. While the owner is fully responsible for maintenance and airworthiness, the airworthiness review staff can be “blamed” as well for signing off an ARC on a plane that had a “minimal AMP”. Perhaps it isn’t adequate for the type of operation or not taking risks into account at all. As long as sensible MX practices in line with the actual use case of an airplane are applied, there shouldn’t be any obstacles. Maintenance. is. very. critical. to. flight. safety!

Quoting EASA:

When evaluating an alternative to a maintenance task issued or recommended by the DAH, such as the extension of TBO intervals, or when considering not to include a maintenance task issued or recommended by the DAH, a risk-based approach should be taken, considering aspects such as the operation of aircraft, type of aircraft, hours and years in service, maintenance of the aircraft, compensating measures, redundancy of components, etc.

AMC1ML.A.302(c)

Pertaining to the above, EASA also published these risk aspects that should be considered.

Risk aspects that should be considered according to EASA

Points 1. to 5. sum up the basics of maintaining an airplane according to EASA Part-ML. Now, let me go into some additional details for completeness.

6. CAMO or CAO

A Pilot Owner can also voluntarily contract a CAMO or CAO. In this case, the owner is not responsible for the maintenance and airworthiness of his plane. This responsibility belongs to the contracted CAMO/CAO. Bearing this responsibility, a CAMO/CAO will track the maintenance status of the airplane, manage workorder packages for maintenance organisations and issue/extend the ARC. Needles to mention here is that the added convenience, service and most importantly the delegated liability come at a price.

The AMP is subject to approval by the the contracted CAMO/CAO. Pilot Owner Maintenance and deviations – see pt. 3 above – are still possible, but are obviously subject to the approval of the CAMO/CAO as well.

Similar to pt. 2 above (except for the owner bearing no responsibility) a contracted CAMO/CAO can also follow the DAH AMM, in which case no individual AMP will be created. I want to emphasize that in both cases, pt. 2 above and using a CAMO/CAO, the airplane will be maintained according to exactly the same instructions (the DAH AMM). Food for thought.

7. Exceptions and special provisions

While legally flight training in an ATO is Part NCO Ops, airplanes in commercial ATOs (“open to the public”) require to be under contract with CAMO or CAO, except when the ATO “adds” an owner’s airplane and only the owner will be trained on it.
For non-profit clubs that operate an ATO (“not open to the public”), airplanes owned or operated (“leased”) need no CAMO/CAO contract.
Also noteworthy: An AMP can be applied to a fleet of airplanes (same type) if they are to be maintained identically.

A quick recap of options for EASA airplane Owners and Pilots:

1. If you contract a CAMO/CAO → same options as ever before
The CAMO can either approve an individual AMP or follow the DAH AMM.
Advantage: Responsibility for airworthiness lies with the CAMO. This can be a liability factor in case things get really ugly in court.

2. If you declare your own AMP → new and harmonized options all over EASA territory for Owners and Pilots
See above.

3. Declare that your airplane will be maintained according to the DAH AMM, then you do not need to create an AMP → While still bearing the responsibility, you can always point to the DAH AMM, as that is the basis for maintaining your airplane. This might be a good choice e.g. if you do not want a CAMO/CAO but choose a “drop keys, no questions asked” style of maintenance, for instance due to resale value, peace of mind or ease of operation and would like to have the option to point at the DAH AMM for liability reasons.

8. Conclusion and Recap

EASA’s Part-ML provisions allow maintenance of light airplanes in a very similar fashion to N-reg planes (FAA Part. 91), which, in the end, will materialize better, more tailored ways of maintenance at bearable costs.

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