Why Aircraft Maintenance Shops Don’t Accept Owner-Supplied Parts: Understanding the Safety, Legal, and Business Realities

Table of Contents

• Introduction – The Common Misconception About Aircraft Parts
• The Regulatory Foundation – Why Aviation Parts Are Different
• Safety Considerations – Why Source Matters
• Legal and Liability Implications
• Business and Administrative Challenges
• The Research and Verification Process
• When Shops Do Accept Owner-Supplied Parts
• Understanding the Bigger Picture
• Making Informed Decisions as an Aircraft Owner
• Conclusion – Respecting the Complexity
• Frequently Asked Questions
• Sources

Introduction – The Common Misconception About Aircraft Parts

We hear it a lot: “I found the same part online for less. Why won’t the shop install it?” Aviation is not automotive. The installer, whether an A&P or repair station, is responsible for determining that a part is eligible, properly documented, and airworthy before returning the aircraft to service, and that responsibility carries both regulatory and practical consequences that most owners never see [1][3].

Let’s unpack the safety, legal, and business realities behind shop policies on owner supplied parts, and how to work productively with your mechanic to control costs without compromising airworthiness.

The Regulatory Foundation – Why Aviation Parts Are Different

FAA Certification Requirements

• In certificated aircraft, parts must be produced and installed under defined FAA pathways such as OEM production approval, Parts Manufacturer Approval, or other acceptable sources identified in regulation, so the installer can determine eligibility and conformity before approving the aircraft for return to service [1][4].
• Owner produced parts are a specific pathway in §21.9(a)(5) that allows an owner or operator to produce a part for maintaining or altering their own product. They cannot be produced for resale [4][5].
• PMA is FAA approval for a manufacturer to produce replacement or modification parts to an approved design and quality system, while STCs approve design changes and may specify particular parts as part of the approved change [2][4].

The Paper Trail Requirement

• The installer must use methods, techniques, and practices acceptable to the FAA and determine that any part installed is eligible and acceptable before returning the product to service. That includes verifying origin, documentation, and conformity of the article [1][3].
• FAA guidance calls for particular caution when the origin of parts cannot be determined and emphasizes proper documentation, especially for parts obtained from foreign sources [1][4].
• Practically, this means shops review chain of custody and traceability documents before installation to substantiate airworthiness and eligibility [1][2][4].
• Note on recency: AC 20-62E received a major revision in 2018 and a subsequent Change 1. Both reinforce installer responsibility and the need for careful vetting of parts of uncertain origin [1][8].

Safety Considerations – Why Source Matters

Counterfeit Parts in Aviation

• FAA guidance warns that purchasers may not fully appreciate the hazards of replacement parts whose acceptability for installation on a type certificated product has not been established. Receiving parts without clear origin or documentation triggers added scrutiny for the installer who must determine acceptability and eligibility prior to return to service [1][2].

Quality Control Standards

• Acceptable parts must meet the design and quality requirements of the approved article or standard, and installation must follow methods acceptable to the FAA. “Will fit” is not good enough. The installer must be able to establish eligibility and conformity through documentation and inspection [1][2][4].
• “Standard parts” may be used when they meet FAA criteria, but the mechanic still must determine eligibility and traceability as part of the airworthiness decision. Many shops streamline this by maintaining an internal list of pre vetted standard parts, paired with documentation, to speed eligibility determinations in line with Part 43 and AC guidance [3][8].

Legal and Liability Implications

Mechanic Liability and Certification

• The person performing the maintenance and signing the approval for return to service is responsible for the airworthiness of the work and the parts used. This includes determining that each article is eligible and that maintenance is performed using acceptable methods, techniques, and practices [1][3].
• That responsibility is why mechanics may decline to install parts they did not source or cannot adequately vet. When they sign the return to service, they own the decision [1][2].

Shop Insurance and Risk Management

• Insurance and risk management concerns are real business factors. The shop’s exposure is tied to what it installs and approves. When a part’s pedigree or documentation cannot be validated with confidence, the risk profile changes, and so do shop policies. This is not a regulatory mandate, but a practical reality of operating a maintenance business within the FAA framework [1][3].

Business and Administrative Challenges

The Hidden Costs of Owner-Supplied Parts

• Verification time. Cross checking part numbers and supersessions, confirming applicability to your aircraft’s make, model, and serial number, and aligning with approved data requires real labor. The installer must determine eligibility before return to service [1][3].
• Documentation review. Establishing traceability and origin, and sorting out missing or incomplete paperwork, takes time. FAA guidance explicitly calls for caution and proper documents when origin is uncertain [1][2][4].
• Rework and delays. If the part does not conform, lacks paperwork, or is not exactly applicable, the project pauses while an acceptable article is sourced and work is rescheduled [1][2].

Warranty and Support Issues

• When shops do not control the supply chain, warranty and technical support become complicated. If a part fails early or is incorrect, owners often expect the shop to fix it immediately. Without supplier leverage or enforceable warranties, that becomes costly and operationally risky. This is why many shops keep procurement in house under the same regulatory responsibilities that govern installation [1][3].

Inventory Management and Cash Flow

• Parts sales help offset the overhead of research, receiving inspection, documentation control, returns management, and shelf spares the shop maintains to keep aircraft moving on schedule. Owner supplied parts remove that support while leaving the administrative burden in place [1][2].

The Research and Verification Process

What Mechanics Must Verify

• Eligibility and applicability. The part must be eligible for installation on the specific product before return to service [1][3].
• Conformity and traceability. Documentation must establish that the part conforms to the design and quality requirements and that the source is acceptable [1][2][4].
• Approved data. Installations are performed using methods, techniques, and practices acceptable to the FAA per Part 43 [3].

Time Investment in Unknown Parts

• New or unfamiliar suppliers require extra verification, including credentials, documentation, and often additional inspections, because the installer bears responsibility for the part’s acceptability [1][2].
• All of this is doable, but not free. It is why shops often prefer to source parts themselves or assess a handling fee when accepting owner supplied parts [1][2].

When Shops Do Accept Owner-Supplied Parts

Typical Shop Policies and Fees

• Many shops that accept owner supplied parts charge a handling or verification fee to cover the additional research, receiving inspection, documentation review, and risk they assume when they did not control procurement. That fee reflects administrative work tied to the installer’s regulatory responsibilities [1][2].

The Administrative Burden

• Expect requests for advance documentation, clear traceability, and time for the shop to verify eligibility before the airplane is opened up. That helps identify issues early and maintain compliance with the requirement to determine eligibility and use acceptable methods and practices [1][2][3].

Owner Produced Parts vs. Owner Supplied Parts

• Owner produced parts under §21.9(a)(5) allow the owner to produce a part for their own aircraft by managing the production process such as design, specifications, material selection, or oversight. These parts cannot be made for resale [4][5].
• Success with owner produced parts hinges on teamwork. Engage your mechanic early. The mechanic has to be willing to install and sign off the part and will still ensure it meets the “equal to original” standard when applicable [5][6][2].
• If OEM drawings are not available, reverse engineering with proper data and material verification may be necessary to ensure equivalency [7][5].
• Importantly, even if documentation appears in order, a mechanic may choose not to install an owner produced part based on professional judgment and liability considerations. That discretion is inherent in the requirement to determine airworthiness and eligibility before return to service [5][6][3].

Understanding the Bigger Picture

Building Trust Between Owners and Shops

• Discuss parts strategy before work begins. Agree on required documentation, whether owner supplied or owner produced parts are appropriate for the task, and how fees or timelines will be affected. This aligns expectations with the installer’s responsibility to verify eligibility and use acceptable methods [1][2][3].

Alternatives and Compromises

• If your goal is cost control, ask about PMA parts approved for your aircraft, standard parts where appropriate, or repair options backed by approved data. These avenues can offer savings while maintaining a clean paper trail [4][8].
• For hard to source legacy parts, consider an owner-produced approach with your mechanic’s guidance and full documentation [5][6].

Making Informed Decisions as an Aircraft Owner

Questions to Ask Your Maintenance Shop

• What is your policy on owner supplied or owner produced parts, and what documentation do you require to determine eligibility and conformity [1][2]?
• Are PMA parts acceptable for this task, and are there standard part options where appropriate [4][8]?
• What are the handling or verification fees and how do they impact the timeline and warranty?

Cost-Benefit Analysis

• The cheapest part price is not the total cost. Add handling fees, verification time, potential shipping delays, and the risk of re procurement if the part is ineligible or undocumented. The installer must verify eligibility and acceptable methods regardless of who buys the part [1][2][3].
• A long term relationship with a shop that controls sourcing can reduce downtime and surprises, because traceability, supplier support, and documentation control are built into the process [1][2].

Conclusion – Respecting the Complexity

We are all aiming at the same target: safe, compliant, and economical flying. Shops are not trying to be difficult. We are bound professionally and legally to verify that every part we install is eligible, documented, and airworthy. Understanding that framework makes the policy on owner supplied parts easier to accept. Bring us into the conversation early, and we will help you find an approved, well documented path, whether that is OEM, PMA, standard parts, or a properly executed owner produced solution.

If you are weighing parts options for an upcoming inspection or upgrade and want a clear, compliant strategy, let’s talk. We can review your goals, outline acceptable parts pathways, and manage the maintenance so you stay safe, legal, and on budget.

Frequently Asked Questions

Sources

1. FAA AC 20-62E, Change 1: Eligibility, Quality, and Identification of Aeronautical Replacement Parts
2. FAA AC 20-62E (original): Eligibility, Quality, and Identification of Aeronautical Replacement Parts
3. 14 CFR Part 43 – Maintenance, Preventive Maintenance, Rebuilding, and Alteration
4. FAA AC 20-154A: FAA Approval of Parts, Materials, and Appliances
5. AOPA – Aircraft Maintenance: Owner-Produced Parts
6. Savvy Aviation – Owner-Produced Parts
7. Cessna Flyer – Owner Produced Parts: Regulations, Interpretations, and Applications
8. AOPA – Aircraft Maintenance: Understanding Standard Parts