Owner-Pilot Preventive Maintenance Under FAR Part 43

Owner-pilot preventive maintenance is one of aviation’s best-kept practical advantages—the FAA explicitly allows certificated pilots to perform 31 specific maintenance tasks on their own aircraft without an A&P (Airframe and Powerplant mechanic). This legal authority saves money, deepens knowledge of your aircraft, and keeps you empowered rather than dependent on maintenance shops. However, the legal boundaries are precise and consequential: exceeding your authority violates FAR Part 43 and can ground your aircraft or create liability issues. E3 Aviation Association clarifies exactly what FAR Part 43 Appendix A permits, how to properly document your work, and where pilots commonly exceed their authority. Understanding this distinction between what you can legally do versus what an IA must handle is fundamental to safe, legal aircraft ownership.

What FAR Part 43 Appendix A Actually Allows

FAR Part 43, Appendix A, defines preventive maintenance as actions specifically limited to the replacement of “small standard parts” and simple adjustments. Critically, these tasks are not inspections—they’re replacements and adjustments of components that are known to wear and require replacement at predictable intervals. Furthermore, FAR Part 43 explicitly defines what pilots can do, and anything outside that list requires an A&P or IA to perform.

The regulatory language is precise: “the replacement of those Class 1 or Class 2 components (engines, propellers, major airframe components) is excluded. Additionally, work affecting the aircraft’s type certification, structural integrity, flight control systems, or powerplant function requires an A&P.” This means pilots cannot perform overhauls, major repairs, system modifications, or inspections—they can only replace small components and perform adjustments that don’t require troubleshooting or interpretation.

The 31 preventive maintenance tasks (officially listed in FAR Part 43 Appendix A(c)) include oil changes, spark plug replacement, air filter cleaning, battery maintenance, light bulb replacement, landing light replacement, and a range of specific inspections and adjustments. Specifically, pilots can perform these tasks and legally sign off the work in the aircraft logbook—you are certifying that the maintenance was performed and the aircraft remains airworthy in that respect.

The psychological distinction matters: when you perform owner-assisted work during an annual (helping an IA), you’re not signing off anything. The IA signs off the annual. When you perform owner-pilot preventive maintenance, you are performing the work and signing it off yourself. This authority is real and valuable, but it comes with responsibility for accuracy and legal compliance.

The 31 Preventive Maintenance Tasks Pilots Can Legally Perform

The FAA’s definitive list in FAR Part 43 Appendix A(c) includes these specific tasks. Read through this carefully—many pilots are surprised at what they can legally do, and equally surprised at what they cannot.

Lubrication and fluid service:

• Cleaning or replacing engine oil and oil filters
• Servicing fuel strainers and screens
• Draining fuel tanks
• Cleaning spark plug electrodes (not replacing or gapping)
• Servicing landing gear wheel bearings
• Lubricating aircraft components (hinges, cables, control surfaces)

Component replacement:

• Replacing spark plugs (not adjusting gap, not troubleshooting ignition issues)
• Replacing air filters and cabin air filters
• Replacing fuel strainer elements
• Replacing and servicing batteries
• Replacing brake fluid (not repairing brake systems)
• Replacing landing light bulbs and navigation light bulbs
• Replacing instrument light bulbs
• Replacing cabin lighting bulbs
• Replacing seat belts

Inspections and checks (limited):

• Inspecting visual condition of engines, airframe components, control surfaces
• Inspecting magnetic compass accuracy
• Checking engine cylinders for compression (but not interpreting or making repairs)
• Checking landing gear free and correct movement
• Inspecting brakes and brake linings for wear (visual only, not adjusting or repairing)

Operational checks:

• Checking flight control operation (moving controls and verifying response, not making adjustments)
• Checking magneto operation and timing (basic checks, not adjustments)
• Checking vacuum/pressure system operation
• Checking electrical system operation

Specifically, the critical constraint is “replacement of small standard parts”—when the FAA approved these tasks, they contemplated only replacement, not diagnosis, troubleshooting, adjustment, or repair. Additionally, the work must not affect the aircraft’s type certification, control system function, or powerplant operation. Consequently, if a task requires troubleshooting (why is the alternator not charging?), problem-solving (what connector is loose?), or system adjustment (setting the mag timing), it’s beyond your authority.

Tools, Parts, and Airworthiness Standards

Performing preventive maintenance legally requires the right tools, approved parts, and adherence to manufacturer specifications.

Tools: You need appropriate hand tools—screwdrivers, wrenches, pliers, torque wrench (for critical fasteners), plug socket, and compression testing equipment if checking cylinder compression. Additionally, you need a propeller-balancer or dynamic balancer for any spark plug work (compression checks disrupt the engine’s static balance). Most aircraft mechanics’ tools are accessible and reasonably priced; specialized tools can be rented or borrowed from aviation shops.

Parts: All replacement parts must meet FAA specifications. For spark plugs, use the exact type specified in your engine’s POH—Champion, Tempus, or other approved types, in the exact heat range and gap. For filters, use OEM (original equipment manufacturer) approved filters or equivalents meeting the specification. Additionally, never use automotive parts substitutes unless explicitly approved by your engine manufacturer—a automotive-grade oil filter might not meet aviation pressure specifications and could fail catastrophically.

Airworthiness standards: Any preventive maintenance work must restore the aircraft to an airworthy condition. This means: fasteners must be torqued to specification, all connections must be secure and double-checked, fluids must be filled to proper level, and you must verify the work doesn’t create new problems. Specifically, after an oil change, you must verify the oil level is correct (overfilled oil can get into the engine’s breather system; underfilled oil starves bearings). After spark plug replacement, you must verify you didn’t cross-thread a plug or strip the engine block thread.

Furthermore, if you’re uncertain about proper procedure, torque specification, or part selection, stop and consult your aircraft’s POH, your engine manufacturer’s manuals, or an A&P. Guessing at critical work is a safety issue and a legal violation if something goes wrong.

How to Properly Log Preventive Maintenance Work

Documentation is the difference between legal, defensible maintenance and unrecorded work that creates liability. Every preventive maintenance task must be logged in the aircraft’s maintenance logbook.

Format your entry as follows:

Date performed, aircraft total time, work description, signature and credentials.

Example entry:

4/5/2026, 1,247.5 hours total time. Changed engine oil and filter, filled to 7.5 quarts with AeroShell 15W ashless dispersant. Oil screen clean, no metal particles observed. Tested engine ground run—smooth operation, oil pressure 55 psi, oil temperature 160°F. Airworthiness verified. Signed, John Smith, Commercial Pilot Certificate #123456789.

Key elements:

• Date: The specific date work was performed
• Aircraft time: Total flight hours at time of maintenance (used to establish maintenance interval history)
• Specific description: Not just “oil change” but “changed engine oil from 15W mineral to 20W ashless dispersant, filter replaced with Champion element #X, oil level set to 7 quarts.” Details matter for future maintenance trending.
• Any observations: “No metal particles in oil screen” or “spark plugs showed light tan deposits, normal” create a record of aircraft condition
• Verification: “Engine run-up completed, smooth operation, no unusual vibration or noise” documents that the work didn’t create new problems
• Signature and certificate number: Your full name, certificate type, and certificate number. This proves you were legally authorized to perform the work and takes personal responsibility for accuracy.

Furthermore, the entry should be legible and permanent—use pen (not pencil), and never obliterate or white-out entries. If you make a mistake, cross it through with a single line, initial and date it, then write the correction below. Aviation maintenance records are legal documents and must be audit-able.

Additionally, maintain a separate record outside the logbook: photos of work performed, serial numbers of parts replaced (for traceability), and any troubleshooting or anomalies observed. If an FAA inspector questions your work or if a maintenance issue arises, your detailed records demonstrate diligence and transparency.

Where Pilots Exceed Their Authority (And Get in Trouble)

FAA enforcement actions consistently show patterns where pilots, intending to be proactive, exceed their legal authority and create problems.

Scenario #1: Troubleshooting and diagnosis. You notice your alternator isn’t charging. You start testing electrical components, trace the problem to a loose connector, tighten it, and everything works. You’ve now performed electrical system diagnosis and repair—work that exceeds preventive maintenance. The correct action: note the problem, log it in the maintenance record, and have an A&P investigate and repair the root cause. Consequently, if you fix it yourself and the same problem recurs, you’re liable. An A&P’s diagnosis and repair provide protection for both you and any passengers.

Scenario #2: Adjustments beyond basic operation checks. You perform a magneto check and notice one mag is slightly low on rpm. You adjust the mag timing to bring it up. You’ve now performed a system adjustment—beyond your authority. Mag timing adjustments require A&P certification and special equipment. The correct action: log the discrepancy and have an A&P perform the adjustment.

Scenario #3: Parts replacement that requires troubleshooting. Your engine isn’t starting reliably. You replace the spark plugs (legal). But if starting problems persist, you cannot diagnose and replace additional components—you can only replace spark plugs. If the real problem is a fouled injector, weak magneto, or contaminated fuel, you need an A&P. Many pilots replace multiple components trying to diagnose a problem; this exceeds preventive maintenance and creates liability.

Scenario #4: Structural or control system work. You notice a cracked skin panel or loose control cable. You cannot repair structural damage or control systems—these affect the aircraft’s type certification and flight safety directly. Even reinforcing a small crack is beyond your authority. Log it and have an A&P repair it.

Scenario #5: Major component work labeled as “maintenance.” You overhauled your landing gear or rebuilt a fuel pump. Even if work was simple, overhauls are beyond owner-pilot preventive maintenance—they’re repairs requiring A&P certification. Additionally, if something fails after you’ve performed unauthorized work, the FAA can argue you created the hazard.

The consistent pattern: pilots stay legal by sticking to the specific 31 tasks and refusing the temptation to diagnose or repair beyond those boundaries. The boundary is clear in writing; the challenge is psychological—you know your aircraft better than anyone, and your instinct is to fix problems. Resist that instinct and stay within legal bounds.

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