Owner Assisted Maintenance Under Part-ML: What Private Owners Can Actually Do

Owner Assisted Maintenance Under Part-ML: What Private Owners Can Actually Do

Meta description: Owner assisted maintenance under Part-ML lets you work on your own aircraft legally. Here’s exactly what EASA allows and how to stay compliant.

You bought an aircraft to fly it, not to watch it sit in a hangar waiting for an engineer’s schedule to clear. Part-ML opened real possibilities for private owners to perform certain maintenance tasks themselves—but the regulation is precise about what qualifies, who signs what off, and how you document it. Get this wrong and your aircraft’s airworthiness is compromised, not just on paper but potentially at your next ramp check. This guide covers exactly what owner assisted maintenance means under Part-ML, where the boundaries sit, and how to execute it without creating compliance headaches.

What Part-ML Actually Says About Owner Assisted Maintenance

Part-ML (Annex Vb to Regulation (EU) 2018/1139) governs continuing airworthiness for aircraft not used in commercial air transport. ML.A.803 specifically addresses pilot-owner maintenance, but the term “owner assisted maintenance” describes a related but distinct concept that trips up many owners.

Pilot-owner maintenance under ML.A.803 allows the owner to perform limited maintenance tasks and release the aircraft to service themselves—no engineer required. Owner assisted maintenance is different: you’re working under the supervision of a licensed engineer who retains responsibility and ultimately releases the aircraft.

The distinction matters for three reasons:

1. Task scope. Pilot-owner maintenance is restricted to the task list in Appendix II to Part-ML. Owner assisted work, supervised by a certifying engineer, can extend beyond that list.

2. Release authority. Under pilot-owner privileges, you sign the release. Under assisted maintenance, the supervising engineer signs.

3. Record requirements. Both require documentation, but the chain of accountability differs.

The regulation intentionally created flexibility here. EASA recognised that many private owners have genuine mechanical competence but lack formal licensing. Owner assisted maintenance provides a legal pathway to use that competence while maintaining the oversight structure that keeps aircraft safe.

Which Tasks You Can Perform Yourself

Appendix II to Part-ML lists the specific tasks a pilot-owner can perform independently without engineer supervision. These include:

• Replacement of landing gear tyres, doors, seats, cowlings, and fairings
• Simple fabric repairs not requiring rib stitching
• Servicing of batteries, filters, and landing gear shock struts
• Replacement of spark plugs, hoses, and elastic shock cords
• Component replacements designed for rapid removal (safety wire, split pins, cotter keys)
• Servicing operations such as lubrication, topping up fluids, and tyre pressure checks
• Inspections and operational checks that don’t require disassembly beyond normal access covers

These tasks share common characteristics: they’re maintenance items with established procedures, limited complexity, and low risk of consequential damage if performed incorrectly.

For anything outside Appendix II, you have two options. First, you can simply hand the aircraft to a Part-145 organisation or independent certifying engineer and let them handle everything. Second—and this is where owner assisted maintenance becomes valuable—you can perform the work under an engineer’s direct supervision, with the engineer retaining release authority.

The second option saves money without compromising airworthiness. You’re providing labour under expert oversight, reducing the engineer’s billable hours while they ensure the work meets standards.

The Supervision Requirement: What “Assisted” Actually Means

Owner assisted maintenance isn’t a loophole to perform major work and then ask an engineer to rubber-stamp it afterwards. The supervising engineer must be involved before, during, and after the work.

Before the task: The engineer reviews the procedure, confirms the owner understands the steps, and ensures proper tooling and parts are available. This might happen in person or via detailed communication, depending on task complexity.

During the task: The level of direct supervision varies. For straightforward work, the engineer might check in at key stages. For anything involving flight controls, engine internals, or structural components, expect continuous oversight.

After the task: The engineer inspects the completed work, confirms compliance with the applicable maintenance data, and releases the aircraft. Their signature on the release confirms they accept responsibility for the work performed under their supervision.

If an engineer is unwilling to supervise a particular task, that’s information worth respecting. Their licence is on the line. Push-back usually indicates either task complexity beyond reasonable assisted maintenance scope or concerns about the owner’s capability on that specific job.

Some CAAs have issued additional guidance on supervision standards.

Documentation Requirements You Cannot Skip

Maintenance records under Part-ML aren’t optional paperwork—they’re the legal evidence that your aircraft is airworthy. ML.A.305 specifies what you must retain:

Aircraft continuing airworthiness records must include the aircraft total time, current status of ADs, current inspection status, and details of modifications and repairs.

Maintenance records must document the date, a description of the work, applicable maintenance data used, the person who performed the work, and the person who released it. For owner assisted maintenance, both names appear: yours as the person who did the work, the engineer’s as the person who supervised and released.

The release to service entry must clearly state what was done, reference the applicable procedures or instructions, and confirm the aircraft is approved for return to service. ML.A.801 covers release requirements in detail.

Sloppy records create real problems. A ramp inspection that finds maintenance entries without clear release authority can ground your aircraft on the spot. Worse, a maintenance-related incident with poor records history shifts liability in directions you don’t want.

Keep your records current, organised, and accessible. If your system involves paper logbooks scattered across your hangar, office, and flight bag, you’re creating risk.

Common Mistakes That Create Compliance Problems

Having worked with owners navigating Part-ML, certain patterns emerge repeatedly:

Performing tasks outside Appendix II and self-releasing. This is straightforward non-compliance. The task list exists for a reason. If the job isn’t listed, you don’t have pilot-owner release authority regardless of your skill level.

Failing to use approved maintenance data. You can’t just watch a YouTube video and call it compliant. Maintenance must be performed in accordance with instructions from the type certificate holder, the aircraft manufacturer’s maintenance manual, or approved supplementary data. ML.A.302 is specific about data requirements.

Incomplete record entries. “Changed oil” with a date and signature isn’t sufficient. The entry must reference the maintenance data used, oil type and quantity, and confirm return to service.

Treating AMP optional items as truly optional. If your Aircraft Maintenance Programme includes a task, it’s not optional at that point—it’s your compliance schedule. You can propose AMP amendments through the proper process, but you can’t simply skip inconvenient tasks.

Mixing up EASA and FAA standards. Owners with dual experience sometimes apply Part 91 Preventive Maintenance logic to Part-ML aircraft. The frameworks don’t align, and what’s legal under FAR 43 Appendix A doesn’t automatically transfer.

Working With Engineers: Making Assisted Maintenance Practical

Finding an engineer willing to supervise owner assisted maintenance requires trust in both directions. The engineer needs confidence that you’ll follow instructions, not cut corners, and accept their decision on what qualifies as owner-appropriate work.

Build this relationship gradually. Start with straightforward Appendix II tasks performed independently, then discuss assisted work as they observe your competence. Many engineers prefer owners who ask questions over owners who assume.

Agree on communication expectations upfront. Some engineers want photo documentation at each stage. Others prefer periodic check-ins. Clarify this before starting work, not after you’ve reassembled something incorrectly.

Expect to pay for supervision time even when you’re doing the physical work. The engineer is reviewing procedures, monitoring your progress, and accepting liability for the release. That’s valuable, and pricing it appropriately keeps good engineers in the owner-assisted maintenance market.

How Squawkd Helps

Squawkd maintains your continuing airworthiness records in a format that satisfies ML.A.305 documentation requirements, tracking task status, inspection schedules, and release history. For co-ownership situations, it ensures every owner and any supervising engineers work from the same current maintenance status—eliminating the scattered logbook problem that creates compliance gaps.

Frequently Asked Questions

Can I change my aircraft’s brake pads under pilot-owner maintenance?
Yes. Replacement of brake pads (including discs on certain types) appears in Appendix II to Part-ML as an approved pilot-owner task, provided you follow the aircraft maintenance manual procedures and document the work correctly.

What happens if I perform a task outside the Appendix II list without engineer supervision?
The release to service is invalid. Technically, your aircraft isn’t airworthy, regardless of whether the physical work was done correctly. A subsequent inspection revealing this creates immediate grounding and potential enforcement action.

Does my engineer need to be physically present for all assisted maintenance?
Part-ML doesn’t mandate continuous physical presence for every task, but the supervising engineer determines what level of oversight they require to accept release responsibility. For any work affecting flight safety systems, expect them on site.

Tags: owner assisted maintenance, Part-ML, pilot-owner maintenance, EASA aircraft ownership, continuing airworthiness, ML.A.803, private aircraft maintenance