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I recently did some repair work on my main landing gear.
My Bidule is not outfitted with the brakes as many others are. The brake installation seems to provide some extra support on the composite main gear where the axles and wheels attach.
I built my Bidule with the axles and wheels installed as per the directions with the original kit and found the stress of the landings would eventually cause a failure of the composite main gear where the axles are installed. This portion of the gear cracked and shattered on my last landing about a month or so ago.
I removed the main gear for the fuselage, the axles, and wheels...the original main wheels needed to be replaced as they were starting to crack and it would only be a matter of time before they came off the hubs.
After the wheels and axles were removed I took the composite gear and sanded off the outer finish on both sides of the lower 4"-5" on the legs down to the axle attachment points.
I used denatured alcohol and soaked the legs each for a bit as well as wiping everything down. I wanted to be sure to wash any oil and residue off the areas that were going to be reconstructed and reinforced.
I made a simple form from some scrap 1 x 2 pine and covered it in saran wrap. Then the main gear was set vertically on one side. I used West Systems resin and hardener without any fill at first and coated all the areas of the main gear where I put the pieces back together, making sure to brush in all the areas that needed to be reconstructed. After the resin was put on to coat I added fiber filler to the remaining resin to slightly thicken it and add some strength to the mix. This was then used with the form on one leg at a time. I did one leg one day and then turned the form around to do the same process to the other leg the next night.
The result was very good. After some initial sanding and shaping the main gear looked like it was back to its original dimensions and shape. I did some more sanding with some 120 paper and cleaned everything with denatured alcohol and let it dry.
The next step was to add fiberglas cloth to both legs. Setting the main gear upside down I was able to take some heavier cloth and cut a length that would go from the inside of the leg down and around then back up the leg on the outside. The cloth was then attached with West Systems resin and a pair of small wood black with saran wrap were used on the end of each leg to apply pressure to the cloth and resin wrap.
This was left to set overnight and then the next day I was able to remove the wood blacks and clamps and take a look at the cloth that was applied. I little quick sanding with some 120 and 220 paper to smooth everything out and then cleaned with alcohol again. After this was prepped I then brushed on resin without any filler over the cloth and edges. I wanted to make sure to fill in the weave of the cloth and also allow for the transition from the repaired and reinforced areas to the upper section of the gear. This set over night and the next day I used 220 paper to clean everything up and prep for painting.
After getting all of the landing gear sanded smooth with 220 and 320 paper it was cleaned with alcohol again. I then used Monokote white primer for the base coats on the landing gear, the whole gear was primed and it set overnight. The next day I sanded the primer smooth and then applied another light coat to make sure everything was primed. This was allowed to dry over night and then the next day I applied the Monokote Jet White paint. I did the top and sides of the gear first and then after it was dry I completed the underside of the gear.
Once everything had dried well I took the gear and marked the position of where the new axles would be installed. I drilled 3/8" holes in the gear legs and then used 3/8" cap bolts for the axles. They seem to work just about right as the bolts have a smooth shoulder before the threaded section that is almost perfect in length for the 8" Dubro wheels I planned on installing. The wheel his were drilled out to 3/8" and the bolts were then put into the wheels with washers on each side of the hub. A nut was threaded onto the bolt to lock the wheel into correct position and then the assembly was installed on the main gear through the new axle holes. Nylon lock nuts were used for holding the axle assembly to the main gear.
I used a pair of washers on each side of the gear where the axles are installed. A standard washer and also a larger fender washer. My hope is the washers will distribute the stress of the loads onto the gear over a larger area and reduce the chance of the composite gear failing again.
I'll be giving the new installation a try this weekend and hope the reinforced gear will work well.
Here are a couple pictures of the finished gear and wheels.
My Bidule is not outfitted with the brakes as many others are. The brake installation seems to provide some extra support on the composite main gear where the axles and wheels attach.
I built my Bidule with the axles and wheels installed as per the directions with the original kit and found the stress of the landings would eventually cause a failure of the composite main gear where the axles are installed. This portion of the gear cracked and shattered on my last landing about a month or so ago.
I removed the main gear for the fuselage, the axles, and wheels...the original main wheels needed to be replaced as they were starting to crack and it would only be a matter of time before they came off the hubs.
After the wheels and axles were removed I took the composite gear and sanded off the outer finish on both sides of the lower 4"-5" on the legs down to the axle attachment points.
I used denatured alcohol and soaked the legs each for a bit as well as wiping everything down. I wanted to be sure to wash any oil and residue off the areas that were going to be reconstructed and reinforced.
I made a simple form from some scrap 1 x 2 pine and covered it in saran wrap. Then the main gear was set vertically on one side. I used West Systems resin and hardener without any fill at first and coated all the areas of the main gear where I put the pieces back together, making sure to brush in all the areas that needed to be reconstructed. After the resin was put on to coat I added fiber filler to the remaining resin to slightly thicken it and add some strength to the mix. This was then used with the form on one leg at a time. I did one leg one day and then turned the form around to do the same process to the other leg the next night.
The result was very good. After some initial sanding and shaping the main gear looked like it was back to its original dimensions and shape. I did some more sanding with some 120 paper and cleaned everything with denatured alcohol and let it dry.
The next step was to add fiberglas cloth to both legs. Setting the main gear upside down I was able to take some heavier cloth and cut a length that would go from the inside of the leg down and around then back up the leg on the outside. The cloth was then attached with West Systems resin and a pair of small wood black with saran wrap were used on the end of each leg to apply pressure to the cloth and resin wrap.
This was left to set overnight and then the next day I was able to remove the wood blacks and clamps and take a look at the cloth that was applied. I little quick sanding with some 120 and 220 paper to smooth everything out and then cleaned with alcohol again. After this was prepped I then brushed on resin without any filler over the cloth and edges. I wanted to make sure to fill in the weave of the cloth and also allow for the transition from the repaired and reinforced areas to the upper section of the gear. This set over night and the next day I used 220 paper to clean everything up and prep for painting.
After getting all of the landing gear sanded smooth with 220 and 320 paper it was cleaned with alcohol again. I then used Monokote white primer for the base coats on the landing gear, the whole gear was primed and it set overnight. The next day I sanded the primer smooth and then applied another light coat to make sure everything was primed. This was allowed to dry over night and then the next day I applied the Monokote Jet White paint. I did the top and sides of the gear first and then after it was dry I completed the underside of the gear.
Once everything had dried well I took the gear and marked the position of where the new axles would be installed. I drilled 3/8" holes in the gear legs and then used 3/8" cap bolts for the axles. They seem to work just about right as the bolts have a smooth shoulder before the threaded section that is almost perfect in length for the 8" Dubro wheels I planned on installing. The wheel his were drilled out to 3/8" and the bolts were then put into the wheels with washers on each side of the hub. A nut was threaded onto the bolt to lock the wheel into correct position and then the assembly was installed on the main gear through the new axle holes. Nylon lock nuts were used for holding the axle assembly to the main gear.
I used a pair of washers on each side of the gear where the axles are installed. A standard washer and also a larger fender washer. My hope is the washers will distribute the stress of the loads onto the gear over a larger area and reduce the chance of the composite gear failing again.
I'll be giving the new installation a try this weekend and hope the reinforced gear will work well.
Here are a couple pictures of the finished gear and wheels.
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