> ## Documentation Index
> Fetch the complete documentation index at: https://stem-docs.intellectualpoint.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Flight troubleshooting

> Diagnose and fix the most common drone problems - unresponsive drones, drifting, spinning, and propeller issues.

## Every pilot hits snags

Drones misbehave sometimes - that's normal. The skill is knowing how to diagnose the problem. This is your field guide to the most common Echo Drone issues and their fixes.

## Start here: is it battery or pairing?

The most common problem - "my drone won't respond" - almost always comes down to one quick check: **are the lights blinking?**

<Frame caption="The first question to ask when a drone goes unresponsive">
  <img src="https://mintcdn.com/intellectualpoint/PocgpVBYuYokR5M6/images/drones/troubleshoot-flowchart.png?fit=max&auto=format&n=PocgpVBYuYokR5M6&q=85&s=e60a4ff4bf554e364042e40499d6252a" alt="Decision flowchart: drone won't respond, are lights blinking, yes means re-pair, no means charge" width="1536" height="1024" data-path="images/drones/troubleshoot-flowchart.png" />
</Frame>

## Common problems

<AccordionGroup>
  <Accordion title="Drone won't respond, lights blinking" icon="triangle-alert">
    The pairing between drone and controller failed. **Re-pair** them. If it still won't respond, interference may be the cause - if several drones are nearby, pair them one at a time.
  </Accordion>

  <Accordion title="Drone won't respond, lights NOT blinking" icon="battery-warning">
    The battery has died. **Charge the drone** and try again.
  </Accordion>

  <Accordion title="Propellers keep spinning after landing" icon="fan">
    The left joystick isn't centered at zero. Return it to the middle. If they still spin but the drone won't lift, the propellers may be installed wrong or the battery is low - check A/B placement and charge.
  </Accordion>

  <Accordion title="Drone drifts while hovering" icon="move">
    Use the **trim** buttons to correct the drift (trim opposite to the direction it moves). Also make sure you're flying over a textured, well-lit floor so the optical-flow sensor can hold position.
  </Accordion>

  <Accordion title="Drone spins or props sound uneven after trimming" icon="rotate-3d">
    Usually a propeller problem: (1) propellers installed in the wrong A/B spots, (2) a damaged propeller, or (3) lost pairing. Reinstall or replace propellers, then re-pair.
  </Accordion>

  <Accordion title="Won't take off after a crash" icon="plane">
    Propellers may have come loose or been damaged in the crash. Tighten or replace them, and restart the drone (especially before using headless mode again).
  </Accordion>
</AccordionGroup>

<Frame caption="Keep this handy - the top five fixes at a glance">
  <img src="https://mintcdn.com/intellectualpoint/eW7U9shBQKKM3XX9/images/drones/common-fixes.png?fit=max&auto=format&n=eW7U9shBQKKM3XX9&q=85&s=f6517393e3b5bbd6d87e11c024330063" alt="Quick-reference chart of five common drone problems and their fixes" width="1536" height="1024" data-path="images/drones/common-fixes.png" />
</Frame>

## Replacing a propeller

Damaged propellers are the most common casualty of learning to fly. To replace one:

<Frame caption="Three steps to swap a propeller - always match the A/B letter">
  <img src="https://mintcdn.com/intellectualpoint/eW7U9shBQKKM3XX9/images/drones/propeller-replace-steps.png?fit=max&auto=format&n=eW7U9shBQKKM3XX9&q=85&s=2e503330bbc94fa2c0423218903cc7ed" alt="Three-step diagram: check the A or B letter, remove the old propeller with a wrench, fit the matching type" width="1536" height="1024" data-path="images/drones/propeller-replace-steps.png" />
</Frame>

<Steps>
  <Step title="Check the letter" icon="search">
    Every propeller has an **A** or **B** on the back of a blade. Note which one you're replacing.
  </Step>

  <Step title="Remove the old one" icon="wrench">
    Use the included wrench to grip and pull the propeller straight off the motor shaft.
  </Step>

  <Step title="Fit the matching type" icon="fan">
    Press on a new propeller with the **same letter**. A is forward-rotating, B is reverse - mixing them up makes the drone unstable.
  </Step>
</Steps>

## Replacing a prop guard

<Tip>
  To remove a prop guard, don't pull straight down. Instead, tip or push in the part attached to the motor and it pops right off. Then clip on the replacement.
</Tip>

## When in doubt: restart

Many mysterious problems vanish with a clean restart: power the drone off, power it back on, and re-pair. It resets the sensors and the drone's sense of direction.

<Check>
  You can diagnose an unresponsive drone (battery vs pairing), fix drift with trim, and correctly replace a propeller with the matching A/B type.
</Check>