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Repairing a crashed RC plane
By Paul Walsh Last reviewed
Crashes are part of learning to fly. The good news is that foam planes are designed to be repaired, and a careful repair can leave a plane flying as well as before.
Immediately after a crash
- Throttle to zero and unplug the battery.
- Check the battery for damage and swelling; see LiPo battery safety.
- Collect every piece, however small. They help you rebuild the shape.
The damage check
| Area | What to look for |
|---|---|
| Propeller | Chips, cracks, bent blades: replace |
| Motor and mount | Bent shaft, loose or cracked mount |
| Spinner and prop adapter | Loose or bent |
| Fuselage | Cracks, especially behind the wing and at the nose |
| Wing | Cracks at the root, broken spars |
| Tail | Cracked fin or tailplane |
| Control horns and hinges | Pulled out, torn |
| Linkages and pushrods | Bent, disconnected |
| Servos | Stripped gears; see RC servos explained |
| Receiver and wiring | Loose plugs, damaged aerials |
Choosing the glue
| Glue | Good for | Notes |
|---|---|---|
| Foam-safe CA (with activator) | Quick rigid joints in EPO | Use sparingly; test on scrap |
| Foam-compatible contact adhesive | Flexible joints, EPP | Apply both sides, let it tack, press together |
| Epoxy | Motor mounts, high-stress joints | Heavier; use where strength matters |
| Hot glue (low temperature) | Quick field fixes | Heavy; not for flying surfaces |
| Packing or strapping tape | Field repairs | Adds weight; replace with a proper repair later |
FMS recommends foam-safe CA, tape, and dowel or carbon reinforcement for foam repairs (FMS repair tips).
Repairing a break
- Dry fit the pieces so the shape is exactly right.
- Glue with the right adhesive, holding the pieces aligned with tape or pins while it sets.
- Reinforce across the break: cut a slot with a knife and glue in a thin carbon rod or strip.
- Tidy up with light sanding and a little paint or tape.
Dents and crushed foam
Hot water poured or brushed onto EPO dents often lifts them back out. A heat gun on a low setting works too, but take great care not to melt the surface.
Props, horns and linkages
- Propellers: always replace damaged ones. Never fly a cracked prop.
- Control horns: reglue with epoxy or foam-safe CA; reinforce if they keep pulling out.
- Pushrods: straighten only if the bend is gentle, otherwise replace.
Before the next flight
- Rebalance. Tail repairs add weight in the worst place. See balancing an RC plane.
- Check control directions and throws.
- Range check after any damage near the receiver.
Repairing a wooden plane instead? See foam vs balsa RC planes. If you also fly helicopters, the helicopter crash checklist covers those. Back to the RC planes hub.
Frequently asked questions
What glue should I use on a foam RC plane?
Foam-safe CA for quick, rigid joints, or a foam-compatible contact adhesive for flexible joints. Ordinary CA can melt some foams; test on a scrap first.
Can I fix a cracked propeller?
No. A damaged propeller can fly apart at full speed. Always replace it.
How do I fix dents in foam?
Hot (not boiling) water or careful use of a heat gun on low can lift crushed EPO. Let it dry fully before flying.
Related guides
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Foam vs balsa RC planes
EPO foam, EPP, balsa and composites compared for durability, repairs, weight, wind performance and cost, and which suits a first plane.
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Balancing an RC plane
Why the centre of gravity matters more than anything else on an RC plane, how to find and check it, and how to fix a nose- or tail-heavy model.
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After a crash: checks and repairs
The parts that usually break in a crash, the checks to make before flying again, and a sensible crash kit to keep on the shelf.