RC Plane Crashed —
What to Check

The First 60 Seconds

The instinct after a crash is to retrieve the plane and immediately assess the visible damage. That's fine — but before anything else, kill the throttle and disarm the system if the plane is still powered. A motor that spins unexpectedly during inspection is a hand injury waiting to happen.

Once safe, remove the LiPo from the plane and set it on bare ground — not grass, not inside a bag, not in a pocket. A damaged cell can go into thermal runaway without obvious warning signs, and isolating the battery is the single most important action in the post-crash protocol.

LiPo Check — Non-Negotiable

LiPo batteries are the highest-risk component after a crash. The inspection takes two minutes and should never be skipped:

• Swelling (puffing): Run your fingers along the pack. Any puffiness — even slight — is a retirement signal. A swollen cell has compromised chemistry and must not be recharged.
• Puncture or casing damage: Inspect all four sides. Tears, dents, or exposed cells require immediate disposal. Place the pack in a LiPo safe bag and dispose at an electronics recycling facility.
• Heat: A warm pack after a crash is expected. A hot pack that doesn't cool within 5 minutes is not. Keep it away from flammable materials and monitor until ambient temperature.
• Cell voltage balance: Use a LiPo cell checker (under $10) to verify cell balance. A difference of more than 0.1V between cells on a rested pack indicates internal damage.

A battery that passes all four checks can be recharged normally. One that fails any check is done — the replacement cost is always less than the damage a compromised LiPo causes.

Airframe and Control Surfaces

EPO foam is forgiving, but structural damage affects flight characteristics more than visible cosmetics suggest. Work through the airframe systematically:

• Wing halves: Press gently along the full span. Crunching or separation at the joint means a repair before the next flight — foam-safe CA with activator handles most EPO splits cleanly.
• Fuselage: Check for cracks around the motor mount and landing gear attachment points — these areas absorb the most force in a nose-first or gear-first impact.
• Control surfaces: Move each surface — ailerons, elevator, rudder — through its full range by hand. Resistance, binding, or looseness that wasn't there before indicates a damaged hinge or linkage.
• Linkages and pushrods: Verify that each pushrod is still seated in its control horn. A disconnected linkage on takeoff is an unrecoverable loss of control.

Motor, ESC, and Propeller

Prop strikes are the most common crash outcome, and props are designed to sacrifice themselves to protect the motor bell. Replace any prop with a visible crack, chip, or bend — an out-of-balance prop causes vibration that accelerates bearing wear and affects flight stability.

To check for a bent motor shaft: spin the prop by hand slowly while watching the tip trace. A wobble visible to the naked eye means the shaft is bent. Flying on a bent shaft damages bearings and introduces vibration that can loosen other hardware over time. Shaft replacement or motor replacement is the correct fix.

The ESC rarely sustains visible damage from crash impact, but check the wiring for any pulled connectors or exposed solder joints before reconnecting power.

Servo Check

Servos can sustain internal gear damage in a hard impact without any external sign. The quickest field test: a servo tester connects directly to the servo output and cycles it through full range without needing the receiver or transmitter. Watch for:

• Grinding: Internal gear strip — replace the servo before next flight
• Partial range: Gear damage or internal stop failure — replace
• Jitter at center: May indicate electronics damage inside the servo — test at the field before deciding
• Smooth, full-range movement: Servo passes — move to the next one

Check every servo that connects to a control surface, not just the ones near the crash impact point. Vibration from a hard landing travels through the airframe and can damage servos far from the point of contact.

Pre-Flight After a Repair

After completing any repairs, run a full control check before committing to flight. With the transmitter on and the plane powered (prop clear of obstacles), verify that every control surface moves in the correct direction, through full travel, with no binding. A range check — walking 30 meters away and verifying control response — confirms the radio link is clean before takeoff.

A repair that holds on the bench doesn't always hold under flight loads. For significant structural repairs, a short hover or low pass on the first flight back allows a visual check before climbing to normal altitude.