5.12 Maintenance, Inspection & Preflight (§107.49)

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Part 107 prescribes no maintenance program. There is no annual, no 100-hour inspection, no airworthiness certificate, and no mechanic's signature. 14 CFR Part 43 — the maintenance rule for manned aircraft — does not apply, and Part 21 does not apply either, unless the aircraft will be flown over people under §107.140 as a Category 4 operation. All of that is replaced by a single standard, and everything in this lesson hangs off it: condition for safe operation.

§107.15 — the standard

• The remote PIC makes the determination, before each flight. The FAA asks this directly: responsibility to inspect the sUAS to ensure it is in a safe operating condition rests with the remote pilot in command — not the owner, and not the visual observer.
• Paragraph (b) is a continuing obligation. The duty does not end at takeoff. If you learn mid-flight that the aircraft is no longer safe, continuing is a violation. This is the regulatory basis for “land it when the anomaly appears,” and it means that decision is not a judgment call.
• §107.15 is not waivable.

Scheduled and unscheduled maintenance

AC 107-2A defines sUAS maintenance as scheduled and unscheduled overhaul, repair, inspection, modification, replacement, and system software upgrades of the aircraft and its associated elements. Read that last item again: firmware updates are maintenance. Treat them with the discipline you would give to replacing a motor.

That bottom-left cell is a published FAA sample question. Under what condition should the operator establish a scheduled maintenance protocol? When the manufacturer does not provide a maintenance schedule. Not never, and not only after an accident. You build the schedule out of your own logged data until it tells you what wears out and when.

Who may perform maintenance

• There is no certificate requirement. No A&P mechanic, no repairman certificate, no Part 145 repair station is needed to work on a Part 107 sUAS. The remote PIC or the owner may do it.
• Follow the manufacturer's instructions. The manufacturer may require specific personnel for particular tasks — warranty work, sealed assemblies, calibrations requiring proprietary tooling.
• If the manufacturer cannot or will not do the work, it should be completed by personnel familiar with that specific small UAS and its components, in accordance with the manufacturer's instructions or, in lieu of those, within known industry best practices.
• Some jobs need equipment, tools or training you may not have — motor bearing replacement, ESC firmware flashing, IMU and gimbal calibration, structural bonding, battery pack repair. Send those out.
• If the equipment cannot be restored to a condition for safe operation, replace the component or the aircraft. That is the AC's own answer and it is the exam answer.

Recordkeeping

Part 107 requires no maintenance records and prescribes no format. AC 107-2A treats recordkeeping as a best practice and the ACS tests it as “appropriate record keeping.” Hardcopy or electronic logbook, your choice — but log the whole system, not only the airframe: the aircraft, the control station, launch and recovery equipment, command-and-control link equipment and antennas, the payload, and any other component required for the operation.

• What to record: inspections and findings; maintenance, preventive maintenance and repairs; alterations; component replacements with part and serial numbers; time-in-service by component; defects discovered and the corrective action; deviations from manufacturer specifications; firmware versions with update dates; battery logs per pack (ID, cycles, capacity, internal resistance, storage events, retirement); the date of the last successful preflight check; and flight logs.
• Why it is worth the ten minutes: it produces the maintenance schedule you were told to establish, it tracks component service life, and it documents systemic failures — the way you discover that arm number three keeps cracking.
• §107.7 requires the remote PIC, owner, operator, or person manipulating the controls to present the sUAS and any associated records required to be kept, upon request by the Administrator. Your log is also your first line of defense in an enforcement action or an insurance claim.

§107.49 — the preflight action, enumerated

This is the section to know as a list, because the exam asks which items belong in it. Like §107.15, it is not waivable.

Two sub-lists carry most of the questions. The four environment items: local weather, local airspace and flight restrictions, the location of persons and property on the surface, and other ground hazards. The five briefing items: operating conditions, emergency procedures, contingency procedures, roles and responsibilities, and potential hazards.

One requirement sits outside §107.49 but belongs in the same breath: if a visual observer is used, §107.33 requires that the VO can see the aircraft as §107.31 specifies and that effective communication is established. Test the radios before you launch, not after.

A complete preflight

AC 107-2A ¶7.3.4 gives a 23-item recommended checklist and Appendix E provides a sample form. 14 CFR Part 43 Appendix D offers a logical way to organize an inspection into subgroups — airframe, flight controls, batteries, engine — but the AC warns it is not comprehensive, because it does not address UAS-specific features such as datalinks or support equipment. Use it as a template, not as the whole program: inspections should be scalable to the aircraft, the program and the operation, and should cover the entire system.

1. Documents — remote pilot certificate, government-issued photo ID, proof of registration, and any Certificate of Waiver or airspace authorization available (§107.7, §107.13). Registration marking legible on the exterior.
2. Site — weather now and forecast; airspace class and authorization in hand; NOTAMs and TFRs; obstacles, wires and towers; location of persons and property; other ground hazards; launch, recovery and alternate landing zones.
3. Structure — frame, arms and booms, folding hinges, landing gear, fasteners, cracks, deformation, previous repair sites; control surfaces, linkages and servos on a fixed wing.
4. Propellers and motors — no nicks, cracks, delamination or warping; correct handedness in every position; a matched set; securely fastened. Motors spin freely with no grinding or bearing play, mounts secure and uncracked.
5. Battery — correct pack for the mission; no puffing, damage or discoloration; secure in its retention; correct voltage; cells balanced; connector clean; temperature within limits; pack ID logged.
6. Control station — charged; sticks and switches free and correct; antennas intact and correctly oriented; display readable; correct aircraft profile selected; failsafe behavior and RTH altitude verified above every obstacle in the area.
7. Control links — bind established, signal strength verified, RF environment surveyed, correct control response commanded from the control station, and VO communication tested (§107.49(c), §107.33).
8. GPS and compass — adequate satellite count (AC 107-2A says at least four; in practice wait for a strong lock), home point recorded and verified, compass calibrated at the site away from ferrous material.
9. Firmware — aircraft, controller, battery and app versions current and mutually compatible. Update in the shop, never in the field, and never on the morning of a paying job.
10. Payload — secure, does not adversely affect flight characteristics or controllability (§107.49(e)), does not obstruct sensors or lighting; any drop mechanism safed.
11. Power — enough for the intended operational time with reserve (§107.49(d)), computed for today's temperature, wind and payload, not for the brochure.
12. Function check — start the propellers and check for imbalance or irregular operation, then a low hover to check stability, drift and vibration before committing to the mission.
13. Crew — §107.49(b) briefing complete, IMSAFE run on everyone, VO positioned and communicating.

Use a written checklist, on paper or on a card, and touch each item. The purpose of a checklist is not to teach you the aircraft. It is to work on the day you are tired, rushed, and confident you remember everything.

The night preflight addendum

• Anti-collision lighting. §107.29 requires lighting visible for at least 3 statute miles with a flash rate sufficient to avoid a collision. Verify it functions, verify it is visible from all directions, and verify the airframe, payload or landing gear is not shadowing it.
• Recompute power. AC 107-2A directs the remote PIC to consider whether the anti-collision lights reduce the power available, potentially requiring a reduced duration of operation. Your night endurance is not your daylight endurance.
• Confirm your own currency — the §107.29(a)(1) requirement that the remote PIC completed the initial knowledge test or §107.65 recurrent training after April 6, 2021 — and confirm official sunset, sunrise and civil twilight for that exact location and date.
• Survey the site in daylight first. Find the unlit towers, cranes, wires, antennas and building edges you will not be able to see later. AC 107-2A adds that in almost all cases involving operations at night, the remote PIC may need to restrict the operational area.
• VLOS is still VLOS. You may not rely solely on the aircraft's anti-collision lighting, the ground control station telemetry display, or a combination of the two, to satisfy §107.31.
• Crew lighting and night vision — red or dimmed lights only, white light announced before use, controller and tablet brightness at minimum, roughly 30 minutes allowed for dark adaptation, reflective vests, and a lighted site perimeter.
• A higher-contrast landing site — an illuminated or high-contrast pad on level ground you inspected in daylight, so you can find it and judge height against it. Brief the night illusions before you launch.

Mitigating mechanical failures

The ACS asks about mechanical failures of all elements used in sUAS operations, such as the battery and any devices used to operate the sUAS — so think in systems, not airframes.

The overarching mitigation is unglamorous: a written checklist that gets used, a maintenance log that reveals trends before they become failures, conservative retirement of components, and the discipline to cancel rather than fly a system with a known discrepancy. §107.15(a) makes flying a known-unsafe sUAS a regulatory violation, which takes the decision out of the realm of opinion.

Declaration of Compliance for Category 2 and 3

A declaration of compliance is a record submitted to the FAA certifying that the small unmanned aircraft conforms to the Category 2 or Category 3 requirements of Subpart D. The designer, producer, or modifier submits it — not the remote pilot.

• Category 2 (§107.120(a)): the aircraft will not cause injury to a human being equivalent to or greater than the severity of injury caused by a transfer of 11 foot-pounds of kinetic energy on impact from a rigid object; has no exposed rotating parts that would lacerate human skin; and contains no safety defects. Category 3 (§107.130(a)) applies the same three criteria at 25 foot-pounds.
• Means of compliance (§107.155) must consist of test, analysis, or inspection, and must be accepted by the FAA.
• Three obligations the DOC places on its holder: label the aircraft as eligible for the category — in English, legible, prominent and permanently affixed; provide remote pilot operating instructions; and maintain a product support and notification process to notify the public and the FAA of identified safety defects.

The maintenance obligations that reach you flow out of those three. Before a Category 2 or 3 operation over people:

1. Verify the exact make, model and serial number appear on an accepted Declaration of Compliance in the FAA's database at uasdoc.faa.gov.
2. Physically confirm the Category 2 or Category 3 label is present on the aircraft.
3. Have and follow the manufacturer's remote pilot operating instructions. They are part of the compliance, not a suggestion.
4. Watch for and comply with product support notifications. A safety defect notice can remove your aircraft from eligibility overnight.
5. Keep the aircraft in its declared configuration. A third-party propeller guard, an added payload, an aftermarket modification, or a repair performed outside the manufacturer's instructions can void the declared compliance. The DOC covers the aircraft as declared — which makes maintaining eligibility a maintenance discipline, not paperwork.

For contrast: Category 4 is the only Part 107 category with a real maintenance regime. It requires an airworthiness certificate issued under Part 21, operation within the approved Flight Manual limitations, and maintenance, preventive maintenance, alterations and inspections performed per the manufacturer's instructions using methods acceptable to the Administrator, with records to match.