Crash Repairs and other part repairs
|1. Landing gear (zip ties)
2. Landing gear (JB Weld)
3. Frames (fishing line)
4. Frames (other methods)
6. Remote glow plug extension
8. Check main and tail shaft
9. Check for bent tail hub
10. Check the fuel tank
|Landing gear: I was shown how to do this by our resident crash expert Louis. So credit goes to him for this idea. In a bad crash the metal skids can be bent and the plastic struts can be broke just above the section that holds the skids. The skids are easy enough to bend back, but what do you do about the struts? Drill two holes side-by-side (with at least a 1/4" between them) above the break. Next CA the bottom part of the broke strut to the top part. Then run zip ties through the holes and around the skids. Then put thick CA around the zip ties and struts then use accelerant to dry the glue.|
|Noel Cross came up with a variation to the above
repair. It looks great! He wrote an article with pictures
of how he did it. Thanks Noel :)
I looked in my scrap box for one to repair and take pictures of. This one I thought was beyond repair as some parts of the plastic were missing. As you will see it came out ok. Because a piece was missing I used a greased ball pen as a former for the jb weld. This is not normally necessary.
To begin the repair, first drill 3 small 1/32 holes on the strut just above the break. Hold the broken bits on with laced copper wire. Then cover the whole arm with a good thickness of jb weld. The only trick is to warm, with a heat gun, the first application of the jbweld. This makes it flow and run all around the wire and fill the drilled holes and any gaps. Let it cool and then build up with the rest of the jb weld. Extra thickness can be applied to the base as a wear pad. The jb weld fills in the gaps between the wires, like a composite, and keeps the whole shebang tight. When the bottom of the jb weld shows wear just add more. If the repair is sanded and painted it becomes invisible from a short distance away. I did also try covering all this with a 'paint on plastic' coat. It worked fine but was a pain to do.
|I got the frame repair idea came from my friend Bruce. When the front forks of the frames get broke in a hard crash, you can stitch them up with fishing line. First put CA on the edges and push them back together. Next use a 1/32" drill bit in your Dremel to make several holes just above the crack. Then drill some offset holes under the crack. Now thread the fishing line through the holes and tie the ends together. Now put thick CA all over the crack and fishing line on both sides. Use CA accelerator to dry it and you will be left with a very strong repair.|
|Other frame repair techniques:
Another method to repair the frames is to glue a piece of carbon fiber over the crack.
Or you could glue the crack back together using plastic weld (an epoxy like glue).
Flybars are cheap, it is best to just replace them. If it has a hard bend then do not use it again, it could eventually fracture there. If however it is not bent bad then use a straight edge ruler to help straighten it. Just place the ruler against the top of the flybar hub and check that the flybar is parallel up/down and sideways.
PS: If you are trying to remove a badly bent flybar but it will not slide through the bearings in the hub, then use a dremel with a cutoff wheel to cut the flybar off at the bearing then pull out the other side.
Glow Plug Extension Repair - 3-14-2007
The glow plug extension is the highest maintenance item on my helicopter. I have had every part of the glow plug extension fail... I have tried many different store bought versions as well at user mods to these. What I have made curently is by far the best that I have used. It is hand made from a variety of things. I start with some good wire. This is the same wire used on lipo battery packs. It is a high strand count 16ga wire. I cut it to 5-1/2 inches. I strip a 1/2" from one end and put a crimp-on connector. On the other side of that connector I cut away the plastic so the edge of the metal sleeve inside is exposed. Next I crimp an r/c car body pin to that side of the connector. I use a car body pin because I have had them last the longest. The alligator clip is okay but the thin material of the clip eventually wears a hole into it and you will get an intermittant connection. You may notice in the picture that the straight side of the body pin is not long enough to fit in the crimp-on connector. I had to bend it to make this work. Now for the other side of the connector I made a mounting plate from a putty knife. The material is strong but flexible. I have had the plates that come on the store-bought glo-ext's crack from pushing the driver on and off. So far the plates I make from the putty knife have held up great! Now for the driver connector I bought some MPI #2925. ronlund.com has them for a few bucks each. I remove the short wire that comes on it then bolt it in the plate I made. I place some heat shrink tubing on the wire I made up, strip the end an 1/8" then solder it to the MPI dummy glow plug. Slide the heat shrink tubing over the threads just behind the nut and heat it. This gives a strain relief for the wire.
|TT Remote glow extension repair - glow plug
Tip: This is for the TT glow plug extension. How many times have you had the remote glow extension break? I have had this happen several times in the 1200 flights I have on Raptor #1. You could just replace it but I prefer to fix it. I bought some insulated wire connectors, then cut the insulation down to the metal on one end (as in <this> picture) then crimp it onto the bad end (the glow plug driver end or the r/c body clip end. BTW: If the r/c body pin breaks you can get another at any shop that sells r/c cars. If the stem on the glow plug driver end breaks then it's time for a whole new extension.
|Remote glow plug extension:
I have had the kind that uses the spring and rubber boot and it kept breaking where it was soldered. There are a couple of good fixes for this. One is to replace it with an alligator clip which is what I did. I punched a hole in the side of the rubber boot around the alligator clamp and would insert the stem of the glow plug through this. This just helped to keep it on but you don't have to make the hole in the boot. Another technique is to make it like the Thunder Tiger extension, use a wire crimp to attach a r/c body clip.
|Remote glow plug extension: (tip submitted by
This is a fix for the other end (where you attach the driver). Stock, the wire is soldered to the post in the extension. When this breaks from fatigue, push the post out along with the plastic insulator sleeve. Now take the top off a burnt Enya glow plug, save the insulator washer, and find a long 2mm screw. I found one from a control horn off an ARF plank. I drilled a 2mm hole in a flat spade connector, removed the insulation from it, and soldered it to the wire. Then I put a flat washer on the screw, put this through the spade, placed an Enya washer on the other side of the spade, then threaded it up through the plastic insulator in the extension base (it is tight at the bottom, might need a little reaming), put another Enya washer on top of the base and tightened down an Enya plug top on the whole enchilada. Put heatshrink over the spade and wire for relief support.
|TT Remote glow extension repair - driver end
In the picture on the left you see I pulled the broken stem out and installed a threaded rod that is normally used as aileron rods connecting to the swashplate on the Raptor 30/50. The plastic insert in the glow plug extension is smaller then the rod on the front end. Insert the rod through the back then screw it into the front section of the insert. Make sure you thread it in far enough so that the unthreaded part of the rod is inside glow plug extension. Now cut off all but 6 millimeters of the end of the rod sticking out of the front of the plug extension.Next get a red crimp on connector. The red ones are for 22 to 18 gauge wire. On one end of the connector I cut off the extra plastic so the metal sleeve is right at the end. Next I thread the metal sleeve of the connector onto the threads of the rod sticking out of the back of the glow plug extension. The metal sleeve in the connector is soft and will thread itself as you turn it on the rod. Thread it on as far as you can then insert the wire from the glow plug extension into the back half of the sleeve and crimp it in place.
If the boom does not have a hard bend or cut then it can be repaired. To remove any dings, find a socket that will fit the inside diameter of the tailboom. Then use a dowel rod to pound the socket through the tailboom. The socket will push out the dings enough that the belt will not hit them.
main and tail shaft:
For this you will need a dial-point indicator.
Main shaft: Remove all four links from the bottom of the swashplate. Next take the head block bolt out. Now you can pull the head assembly, mixing arms, and swashplate off of the main shaft. Now clamp the dial point indicator on the top of the frames and place the pointer at the top of the main shaft. Rotate the main gear clockwise (as viewed from above) and watch the indicator. You should have no more the 0.003" runout.
Tail shaft: Remove the tail blades, then the two bolts that hold each blade grip together. Next remove the nut followed by the two bearings. Then remove the long set screw from the hub. After both sides are off, then the hub can be removed. Clamp the dial point indicator to the tail case and place the pointer at the tip of the tail shaft. Rotate the shaft and watch the indicator. If you have less then 0.003" runout then it is good.
for bent tail hub:
This is easy to check, you don't have to take anything off. Just straighten the tail blades then rotate one so the blade is pointed forward adn is parallel with the tail boom. Measure the distance the blade is from the boom. Now check the other blade. If it is a different measurment then the hub and possibly set screws are damaged.
Be careful when removing and installing a tank in a R30/50. You need to remove the back-right landing skid screw then pull outward on the frames while you slide the tank in place. If you force it in the sharp edges of the frame will cut the tank right on the front protrusions. This will cause tuning problems. To check for a leak take the tank out and plug up the pressure line (the one that goes to the muffler) with a ball link. Do not use a screw to plug the line as air could leak around the threads. Next you need to pressurize it so connect your fuel pump to the main line (the one that would go to the header tank or engine). Pump some fuel in until you see the sides of the tank slightly buldge. Now with the fuel that was just pumped in you will rotate the tank so that fuel is covering one of the front protrusions. If you see fuel squirt out then you have a hole. Use this technique to examine other areas as well. Another way to see the leak is to submerge the tank in some water and pressurize the tank with air. I have a large syringe that I do this with. With either form of pressurizing if the tank is sealed then when you remove the ball link from the pressure line you should hear the sudden release of air.
Repairing the tank: What I do is first clean the tank, inside and out. You do not want any fuel left in it for the next step! Find some plastic to melt over the hole. I found that the plastic dividers in the clear fishing tackle boxes bonds really well. Cut out a small square of the plastic and use a soldering iron to melt the plastic over the whole.