Drone emergencies, lithium batteries and preflight maintenance
Lost link and fly-aways, battery fires and swollen batteries, radio interference, and the preflight inspection and maintenance practices the Part 107 test expects.
Checked against the rules in force on 2026-10-01Things will go wrong eventually: a battery sags, the link drops, a propeller cracks. The Part 107 test checks that you plan for it before it happens.
In-flight emergencies
Under 14 CFR 107.21, in an emergency that needs immediate action you may deviate from any Part 107 rule to the extent needed. For example, a battery fire might force you above 400 feet to reach a safe landing spot. You send a written report only if the FAA asks for one.
Brief your crew on emergency procedures before every flight, including visual observers and anyone at the controls under your supervision.
Losing the link or losing sight
If you lose visual line of sight, regain it as soon as possible. If you cannot, follow your planned procedure: land, hover, or return home. Most drones run a programmed lost-link behavior, such as return-to-home; know what yours does and set a return altitude that clears every obstacle.
Most drones use the 2.4 GHz and 5.8 GHz bands, the same bands as Wi-Fi. Interference is common in built-up areas, and buildings or terrain between you and the drone can block the signal.
Lithium batteries
Lithium batteries can catch fire from short circuits, improper charging, extreme temperatures, crash damage or poor handling. A swollen battery is a warning sign of failure; stop using it. Steadily shorter flight times mean a battery is reaching the end of its life. Follow the manufacturer's charging and storage instructions.
Preflight inspection
Before each flight 14 CFR 107.15 requires you to check that the system is in a condition for safe operation, and 107.49 lists the preflight actions: assess the operating environment, brief participants, check the control links, confirm enough power, and secure anything attached to the drone.
A good inspection covers the airframe, propellers and motors, registration marking, GPS lock, battery levels on both the drone and controller, and the anti-collision light for twilight or night. If you find a defect, do not fly until it is fixed.
Maintenance
Maintenance includes scheduled and unscheduled work, repairs, replacing parts and software updates. Follow the manufacturer's schedule, or build your own if none exists. Records are not required for most Part 107 flights, but they help you track part life and spot trends.
Sources: 14 CFR 107.15 · 14 CFR 107.21 · 14 CFR 107.49 · AC 107-2A ch. 7
Try 5 questions on this topic
Free sample questions with a debrief for each answer.
Which of these can cause a lithium battery fire?
During your preflight inspection you find a cracked propeller. What should you do?
Which component is often called the 'brain' of a drone, combining sensor data and pilot inputs into commands for the motors?
Which is a safe battery charging practice?
Your app asks you to calibrate the compass. You are standing on a parking lot next to your car. What should you do first?
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