What I check first: The obvious broken part is not always the part that makes the next flight unsafe. An impact can loosen a firewall, crack a wing joiner, shift a servo tray, bruise foam, damage a battery, bend a shaft, or pull a control horn without leaving a dramatic mark. I inspect from the point of impact outward and compare both sides of the airplane.
Before you begin: Disconnect and isolate the flight battery immediately if it is dented, crushed, punctured, hot, swollen, or has damaged wiring. Do not power the radio or motor until the propeller and moving parts are safe and the electrical system has been inspected.
Assess the Damage Before Repairing It
| What you find | What it can mean | Best next step |
|---|---|---|
| Nose-first impact | Spinner, propeller, shaft, motor or engine, mount, firewall, battery, and forward fuselage carry the load | Remove the cowl and inspect beyond the visible nose damage |
| Wingtip or cartwheel | Wing joiner, spar, tip, aileron, servo, fuselage wing saddle, and opposite gear can be damaged | Compare both panels for twist, cracks, and movement |
| Hard landing | Gear mount, fuselage formers, wing attachment, battery restraint, tailwheel, and propeller may be affected | Load-check the gear and inspect structure inside the fuselage |
| Tail strike | Stabilizer mount, fin, tail post, elevator or rudder hinges, pushrods, and servos can shift | Sight the tail alignment and test every control under light load |
| Water, mud, or crop landing | Electronics, bearings, connectors, fuel systems, cooling passages, and hidden cavities may be contaminated | Dry, clean, and inspect before applying power |
| Minor-looking foam crease | Internal foam beads, spars, glue joints, or molded channels may be crushed | Flex and compare the area carefully; surface shape alone is not proof |
Work Through the Repair in This Order
- Make the airplane electrically and mechanically safe. Disconnect batteries, shut off fuel and ignition, remove or restrain the propeller, and keep a damaged LiPo in a safe location.
- Photograph and record the impact. Before straightening anything, note where the airplane hit, which parts separated, battery position, switch positions, and any marks showing how loads traveled.
- Remove access panels and equipment as needed. Cowls, hatches, wings, seats, trays, and fairings can hide cracked structure. Do not stop at the first visible break.
- Inspect from the impact point outward. Follow spars, longerons, formers, doublers, motor boxes, wing tubes, joiners, servo trays, and mounting rails into apparently undamaged areas.
- Compare symmetry and alignment. Sight the wing and tail, measure control surfaces, compare landing gear, and check whether the fuselage, stabilizer, fin, motor, and wing still share their intended alignment.
- Load-check without being destructive. Use moderate hand pressure to reveal clicking joints, movement, soft spots, delamination, loose horns, cracked hinges, shifting mounts, and damaged gear attachments.
- Inspect every control and radio component. Check servo cases and gears, mounts, arms, pushrods, clevises, horns, hinges, extensions, receiver antennas, switches, batteries, and connectors.
- Inspect the complete power system. Check propeller, spinner, adapters, shafts, bearings, motor or engine, firewall, ESC, fuel tank and tubing, batteries, connectors, exhaust, and cooling openings.
- Repair, rebalance, and perform a full preflight. After repairs, verify center of gravity, lateral balance, control direction, stabilization direction, failsafe, range, current or engine operation, and hardware security.
- Plan a conservative return-to-service flight. Use calm weather, a large familiar field, a known-good battery, an experienced observer, and a clear glide path. Land at the first abnormal sound or response.
Do Not Hide a Structural Problem
A neat surface does not prove the original strength, alignment, or load path has been restored. Dry-fit the structure, compare it with undamaged reference points, and make sure loads are carried into sound material. More adhesive is not a substitute for missing or crushed structure.
Common Mistakes
- Repairing only the part that visibly broke off
- Reusing a damaged propeller or questionable battery
- Powering the model before checking for a jammed motor or pinched wire
- Assuming foam that springs back has regained full strength
- Skipping CG and control checks because no radio parts were replaced
Before the Airplane Flies Again
- Confirm the repaired structure is straight, secure, and fully cured.
- Check every control direction, hinge, horn, linkage, servo mount, and endpoint.
- Verify the center of gravity and lateral balance with the airplane flight-ready.
- Inspect wiring, batteries, fuel systems, power-system mounts, and rotating parts.
- Perform the manufacturer’s range test after radio or receiver-power work.
- Use a conservative return-to-service flight and land at the first abnormal sound or response.
Related RC Plane Lab Guides
Use the complete preflight checklist, mechanical setup guide, repair overview, and sudden handling-change diagnostic. Return to the RC Airplane Building & Repair Center.
RC Plane Lab provides general educational information. Follow the instructions for your specific airplane, materials, adhesives, covering, engine, motor, batteries, and radio equipment.