Copyright © Rotorway-Rework. All rights reserved.
The weakness of the factory design was apparent after a TR strike. Ralph Congdon from Wenachee WA came up with a superior design. He uses 7075 T6 extrusion for the upper and lower rails. This design keeps the rails in perfect alignment and is very easy to install. Another improvement is the addition of Teflon to the sliders. Belt adjustment is very precise.
1. During a TR strike two of the rails distorted as seen in the photo. I purchased replacements but was concerned about the flimsiness of the adjusting assembly. Through the ROG I learned about the ChopCo system and was impressed by the thoroughness of the design. It seems that all the OEM flaws had been addressed.
2. You need to disconnect the TR assembly from the control cable and then remove the OEM assembly. You will also have to remove several anchor nuts used to secure the tailcone fairing. To release the shaft bearing locking collars one should locate the little dimple and strike it opposite the shaft rotation. If you have had a TR strike the next step would be check out the shaft for runout (trueness). Be advised that some builders lock the bearing collars opposite the shaft rotation! If it does not unlock by striking in one direction try the opposite.
3. If you have the horizontal stab removed pass a straight rod (Broomstick) through the mount holes. Also pass a straight rod (broomstick) through the ChopCo slider bearing holes.The ChopCo unit uses both rods as a sight level to position the assembly. Secure the ChopCo when aligned with the horiz stab and verify all benchmarks before drilling, you only get one shot at this so take your time. Make sure the legs are firmly against the #4 bulkhead. Most times you need to trim the lower tangs to have 90 degrees at the aft mount plate. The instructions provided by Ralph are good and include some photos.
4. When dis-assemblying the OEM unit record the pulley spacer locations. The belt should pass over the bulkhead approximately over the notch. Very important! The sliders are position as far forward as they go during the alignment and drilling phase. The TR drive should be left off during the fitting and drilling.
5. When the drilling and riveting is complete trial fit the tailcone fairing. More than likely you will have to relocate the attachment screws and required anchor nuts. I opted to attach in skin areas not into the ChopCo extrusion. After relocating the holes and anchor nut remember to plug the old holes in the fairing. The metal boom skin in front of the TR drive may also require trimming to allow for adjustments.
6. Don't forget to put the belt on prior to final assembly! Unbelievably easy to omit!
7. Completed ChopCo installation. Expensive YES, but a very good improvement for the drive train. The kit was of high quality and the instructions were adequate for any builder. As with many items for these machines it would flow a lot better on the next one. Experience is a very necessary prerequisite to work on these helos within the RWI stated time frame.