How to Fix an RC Helicopter: Common Problems and Repairs
Most RC helicopter problems come down to a few causes: battery, blades, gears, motors, the link to the transmitter, or bent parts after a crash. Work through them in that order. Toy coaxial helicopters usually need a battery, blade or motor swap; hobby collective-pitch helicopters also need checks of linkages, the swashplate and the flybarless setup. Always repair with the battery disconnected and the transmitter off.
By Kyle HilsonUpdated: October 20263 min read
Symptoms and fixes
| Symptom | Check | Fix |
|---|---|---|
| Won’t lift | Battery, blades, gear | Charge/replace pack, refit blades, replace gear |
| Spins in circles | Tail motor, rudder trim, upper/lower rotor | Trim, replace tail motor, check coaxial gear |
| Drifts one way | Trim, gyro init, bent shaft | Re-init on level ground, trim, replace shaft |
| Shakes / vibrates | Blades, main shaft, feathering shaft | Replace damaged blades and bent shafts, balance |
| No response | Binding, receiver plug, battery | Rebind, reconnect, charge |
| Motor runs, rotor doesn’t | Pinion, main gear, one-way bearing | Replace gear or bearing, set mesh |
| Servo jittering | Servo gears, linkages | Replace servo or gears |
Lift problems are covered in detail in why won’t my RC helicopter lift off.
Step-by-step check after a crash
- Disconnect the battery. Look for cracked frames, canopy mounts and loose screws.
- Check the main blades and tail blades for cracks or chips; replace in pairs.
- Roll the main shaft and feathering shaft on a flat surface; any wobble means bent.
- Inspect the main gear and tail drive (gears or belt) for missing teeth.
- Check ball links: they should move freely without play; replace stretched links.
- Move each servo arm by hand gently; grinding means stripped servo gears.
- Power up with the blades off (or held) and check that all controls move correctly.
Toy and coaxial helicopters
Coaxial helicopters (like many indoor toys) have two rotors turning in opposite directions and a small flybar. Common fixes: swapping A/B blades back to the right positions, replacing a worn brushed motor, replacing the inner shaft after a crash, and replacing the battery when flights get short. Parts are cheap for popular models; check before buying a new toy.
Hobby collective-pitch helicopters
- Swashplate: must be level at mid stick; re-level after servo or link changes.
- Flybarless unit: recheck the setup after a crash, especially if it was knocked loose; see what a flybar is.
- Tail: check the tail pitch slider and tail blade grips for play.
- Belt or torque tube: check tension and the gears on both ends.
- Blade tracking: both blades should run in the same plane; adjust pitch links.
Useful tools and spares
- Hex drivers and a ball-link plier.
- Medium threadlock for metal-to-metal screws.
- Pitch gauge (hobby helis).
- Spare main and tail blades, main shaft, feathering shaft, main gear, ball links.
- Spare battery to rule out battery problems quickly.
Preventing breakages
Practise on a simulator, fly over grass, and use throttle hold (hobby helis) or cut the throttle immediately in a crash: it saves gears, shafts and servos. Do a pre-flight check of blades, links and battery every session, and replace worn parts before they fail in the air.
Repair or replace?
If repair parts cost more than half of a new toy helicopter, replace it. For hobby helicopters repair is nearly always worth it; individual parts are cheap compared to the whole model.
FAQ
Why does my RC helicopter spin around?
Tail trim, a weak tail motor or coaxial rotor imbalance.
Why does my helicopter vibrate?
Damaged blades or a bent shaft are the usual causes.
Can I fix a toy helicopter?
Yes, many parts are sold cheaply for popular models.
What breaks most often?
Blades, shafts, gears and ball links.
More on this topic: the complete RC Helicopters guide covers the basics behind this article.
About 20 years in RC. Mostly boats in the NAVIGA Mini Eco Expert class, with many self-made parts; also a King Motor Baja 5B, a home-built electric plane, home-built nitro planes he has flown, and an RC helicopter. More about SwellRC
