5.7 Maintenance, Inspection, and Condition

Keeping the Aircraft Airworthy

Keeping a small unmanned aircraft system (sUAS) airworthy is both a legal duty and the foundation of safe flight. Two regulations frame it, and the exam tests them by section reference.

Regulatory Basis

• §107.15 — Condition for safe operation. No person may operate an sUAS unless it is in a condition for safe operation, and the Remote PIC must check it before and during each flight. There is no annual inspection or registered-mechanic requirement as in manned aviation; the PIC's judgment is the standard.
• §107.49 — Preflight familiarization, inspection, and actions. Before flight the Remote PIC must assess the operating environment and verify that all links between the control station and the aircraft are working, among other steps such as confirming sufficient power for the intended flight.

A Tiered Inspection Routine

Part 107 does not mandate intervals, so the FAA expects you to follow the manufacturer's guidance and build your own program. A practical tiered routine:

Before every flight (preflight):

• Inspect the airframe for cracks or loose hardware.
• Check every propeller for chips, cracks, or warping, and confirm each is seated and secured.
• Inspect the battery for swelling, damage, or corroded contacts, and confirm charge level.
• Confirm camera/sensor mounts are secure.
• Power up and verify the control link, calibrate the compass if prompted, and confirm a solid GPS lock (commonly 6 or more satellites).
• Test that all control inputs move the correct surfaces/motors.
• Note any firmware alerts — but never update firmware in the field.

Every 10-25 flight hours: inspect motor bearings and mounts, check wiring, clean obstacle-avoidance sensors, inspect gimbal dampeners and landing gear, and review battery cycle count.

Every 50-100 flight hours: replace propellers as a preventive measure even if they look fine, deep-clean the aircraft, inspect electronic speed controllers for heat damage, and consider a professional inspection for a heavily used commercial aircraft.

Common Issues and Symptoms

The toilet-bowl effect — the aircraft orbiting its intended hover point — is the classic sign of compass interference or a bad calibration and is worth recognizing.

Documentation

Maintain records of total airframe flight hours and time since major work, battery cycle counts, repairs (what, when, by whom), part replacements, firmware versions, and incident history (crashes, hard landings). Good logs support warranty claims, prove diligence after an event, and feed your maintenance decisions.

Who May Perform Maintenance

Unlike manned aircraft, an sUAS under Part 107 has no requirement that a certificated mechanic perform repairs, and no mandated logbook format. The manufacturer's manual is the controlling guidance: follow its scheduled-maintenance and component-replacement intervals, and use only approved parts. When a repair is beyond your competence — a structural arm replacement, a motor or electronic-speed-controller swap, or a firmware recovery — the FAA expects you to have it done by someone qualified (often the manufacturer's service center) rather than guessing.

The Remote PIC's enduring duty is the condition-for-safe-operation determination, regardless of who turned the wrenches.

Battery Care Specifics

Lithium-polymer packs are the most failure-prone component, so they earn their own routine. Charge with the manufacturer's charger, never to 100% for long-term storage — store at roughly 40-60% (a "storage voltage" many smart batteries reach automatically). Avoid deep discharges, keep packs out of heat and direct sun, and retire any cell that swells, is physically damaged, or no longer holds its rated capacity. Track each pack's cycle count; many consumer LiPos are rated for roughly 200-300 cycles before capacity loss makes flight times unreliable.

A pack that suddenly reads a lower-than-normal resting voltage, or that gets hot during a normal charge, is telling you it is done.

Firmware Discipline

Firmware updates fix bugs but can also introduce them, change feature behavior, or fail mid-install and brick a controller. The standing rule is to update at home, on a stable release, never in the field immediately before a job. Verify the aircraft flies normally on a low-stakes test flight after any update, and record the version in your log so you can correlate a behavioral change to a specific update if something goes wrong.

When NOT to Fly

Ground the aircraft immediately for any of the following:

• Structural damage anywhere on the airframe.
• A chipped, cracked, or warped propeller.
• A swollen or damaged battery, or abnormal voltage readings.
• A control link that will not establish reliably.
• A motor that is noisy, hot, or vibrating abnormally.
• A GPS that will not reach adequate satellite lock when the operation depends on it.
• A known critical firmware bug per the manufacturer.

For the Exam: The recurring anchor is responsibility plus conservatism — under §107.15 and §107.49 the Remote PIC alone decides the aircraft is safe before every flight, and whenever there is doubt, the credited answer is to ground the aircraft until the issue is fixed, not to fly cautiously around it.