How To Repair a Flying Model Aircraft

Model airplanes can be damaged in a heart-breaking variety of ways.  The majority of my radio control model airplanes are damaged at home, in transit to or from the field or by movers.  On rare occasions, one actually survives life in the hangar giving me the opportunity to crash it at the field.

I would guess that the number one reason a person new to the hobby quits is a crash that destroys his first trainer.  The agony of seeing his hard work and TLC reduced to splinters scattered across the field can be devastating - especially if this is the most significant work they have ever created.  But...

Any damage can be repaired.  Whether the repair is worth doing is for the builder to decide.

There are five things that I factor together to make the decision.

1. How much did I like this model to begin with?
2. Will the airframe be as straight as it was before?  If the answer to this question is no, then that's my answer.
3. How much weight will the repair add?
4. Will the plane look like a patched-together mess or can it be made to look like new?
5. How much time will the repair take compared to building a new component?

I can build pretty fast when I put my mind to it and more often than not I can build a new component in about the same time as it would take to make a major repair.  The end result will be new - not "like" new.

Therefore I usually limit my repairs to minor damage and build a new component when the damage is more severe.  While I'm at it I can modify the model if there were things I would have liked to be different than on the original.

First Steps

Be Conservative in the Heat of the Moment

I've seen a lot of guys throw models away in their disgust following a crash.  At times they've thrown the whole thing away including motor, retracts and servos.  Then to add insult to injury someone usually retrieves the model from the trash and claims it right in front of the person who threw it away.

Take your model (all of it) home.  You can throw it away later if you still don't want it.

Regardless of the type of repair to be made, there are some things that you should always do:

• Search the area carefully and retrieve every piece of the model that you can find.

• Avoid causing further injury to the casualty.  Treat the pieces gently.  You may be able to reuse them even if they look trashed.  Avoid breaking off splinters that may help lock the piece back in place, for example.

• Drain the fuel tank immediately.  Remove the tank or plug the lines.

• Keep clean wood clean.  If the outside of the model is covered in oil and you have loose pieces from inside the model, keep them away from the oily parts.

• Don't delve into the model until you've cleaned the outside of it thoroughly with alcohol unless alcohol will harm the finish.  If that's the case, then use window cleaner instead.  Get all the dirt and especially oil off the model.

• Remove the engine and fuel tank to prevent dripping fuel and oil on the model, to make the model easier to handle and to keep dust out of the engine.

• If the engine is covered in dirt, then do not turn it over.  Blow off as much dirt as possible using compressed air or use a soft brush.  You should attend to the engine as soon as possible because it probably has raw fuel in it that will cause the bearings to rust.

• Check the inside of the airframe for raw fuel.  If present then smother the fuel-soaked areas with corn starch as soon as possible to pull the oil from the wood and to prevent it from soaking farther into the wood.  Replace oil soaked corn starch as often as necessary.  When the corn starch is no longer soaking out oil, leave it in place until the repair is complete.  Then use a soft brush to loosen the corn starch and vacuum it out.

• Remove components that will be in the way while making the repair such as landing gear, pushrods, radio switches, etc.

• Peel back just enough covering to get at the damaged area(s).  Don't remove any more covering than necessary at first. You will undoubtedly have to remove more later, but leaving it in place will help keep undamaged areas clean as well as protect adjacent areas from excessive sanding when new pieces are added.

• Remove pieces that are completely detached but any part that is still hanging on should be left in place at first.  Often a piece can be moved back into its correct position and glued.

Example Repairs

• Repairing Rustik
• Repairing Thwing!
• Rebuilding My Stik 30

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Copyright © 2004 Paul K. Johnson