Troubleshooting

Work each ladder top-down — cheapest check first. These cover failures arising from normal usage; after a crash or hard landing, use the post-crash procedure in Flight Operations and contact RFD instead. If a ladder doesn’t resolve it: support@rocketfastdrones.com with your serial number, a description, photos, and logs (see Support & Warranty).

1. Aircraft does not power up (no start-up tone)

Battery charged? Check resting voltage with a cell checker.
Connection order correct — anti-spark connector first, then the remaining lead(s)?
Connectors fully seated, pins clean and undamaged?
Try a second battery pair. Still dead → contact RFD; do not open the airframe.

2. GCS will not connect

Telemetry radio plugged in, and QGC using the correct serial port and baud rate?
Ground antenna attached and vertical? Aircraft powered and within range?
This aircraft is paired to its delivered radio set — confirm you’re using the matching ground radio.
Try a different USB port/cable; restart QGC.
Bypass test: connect the aircraft by USB — if USB works, the issue is the radio link (see #8).

3. No 3D GPS fix / satellite count stays low

Clear sky view? Move away from buildings, vehicles, metal structures and transmission towers.
Give it time — first fix after transport can take several minutes.
EP250: the GPS/magnetometers are in the wings — confirm the wing cables were connected during assembly (assembly step 5).
Minimum is 6 satellites; wait for ≥ 10 before take-off (see Limitations).

4. Pre-arm / preflight check fails

Read the QGC message — PX4 names the failing check (“Preflight Fail: …”).
Compass errors: move away from metal, vehicles, reinforced concrete and buried services; recalibrate the magnetometer if the aircraft has travelled far from its last calibration site.
Accelerometer/level errors: recalibrate on a level surface.
RC errors: transmitter on, correct model selected, receiver bound.
🚫 Never force-arm past a failed check — it voids the warranty and the check is usually right.

5. Heading wrong / aircraft points the wrong way on the map

EP250: wing GPS/mag cables swapped left-right, or a wing fitted misaligned — check the fiducial marks line up (assembly step 11), and re-seat the connectors.
Recalibrate the magnetometer away from interference.

6. Control surfaces do not sweep at power-up

Power connection order correct? Re-boot the aircraft.
Check servo linkages and horns for jams or damage (unpowered!).
One surface dead → do not fly; contact RFD.

7. Motor sounds rough / uneven at idle

Inspect the propeller for damage — any nick/crack = replace, matched set.
Check for debris in the duct (EP250) or around the prop and vanes.
Spin by hand (unpowered): rough spots or grinding → do not fly, contact RFD.

8. Telemetry link weak or drops in flight

Ground antenna vertical, elevated, with clear line of sight — terrain and obstacles in the path degrade the link well before absolute range does.
Keep the GCS away from other transmitters; check antenna connectors are tight.
Persistent short-range drops → try the spare antenna, then contact RFD.

9. “Corrupt log file” or a log fails to download

Re-download the file — a fresh read often succeeds; prefer downloading over USB rather than the telemetry link.
If a card develops repeated corrupt logs: back up what downloads, then reformat the SD card per SD Card Formatting, or replace it with a recommended high-endurance card (same page). Cheap cards drop log messages.

10. Vibration or EKF warnings in the logs

Check propeller condition and balance first (the usual cause), then motor-mount fasteners (witness marks) and airframe cracks per the damage-tolerance criteria.
Recurring warnings with no visible cause → send RFD the logs before the next flight.