TECHNICAL SERVICE BULLETIN: 104750-000 Beechcraft Series 36 Autopilot Servo Update, Rev A

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TECHNICAL SERVICE BULLETIN: 104750-000 Beechcraft Series 36 Autopilot Servo Update, Rev A Original Bulletin: September 5, 2023 This Document Supersedes: 104686-000 Beechcraft Series 36 Yaw Servo Cable Misalignment PLEASE READ THIS BULLETIN IN ITS ENTIRETY BEFORE CONTACTING DYNON AVIONICS Description This technical service bulletin includes details for implementing two related fixes. Implementing these fixes at the same time is recommended, as both require accessing and removing several of the same parts. This bulletin identifies the specific tasks and parts required for each fix, as some aircraft may have already been updated with the Yaw Servo Cable Misalignment Fix (see below). Yaw Servo Cable Misalignment Fix Dynon has received reports of Beechcraft Series 36 aircraft where the yaw servo bridle cable on one side of the capstan is misaligned by a few degrees (see Figure 1). Over time, this misalignment could lead to wear on the capstan's grooves. This bulletin details the fix (see Figure 1) for the misalignment. Figure 1: Before/After Implementing the Yaw Servo Cable Misalignment Fix Bracket Assembly Brace Attachment Fix Dynon learned that existing pitch/yaw servo bracketry installations in Beechcraft Series 36 aircraft may introduce higher loads into aircraft structure at bulkhead FS207 than originally calculated. However, Dynon has received no reports of failure or damage in this area occurring in the field. This bulletin details a fix (see Figure 2) to prevent any potential issues in this area. Figure 2: Before/After Implementing Bracket Assembly Brace Attachment Fix Applicability and Affected Equipment This bulletin affects the following certified aircraft models. • Certified Bonanza 36, A36, A36TC, B36TC models with autopilot servo installations. Required Actions Inspect before next flight, and if no issues are observed, perform the work in accordance with this service bulletin within the next 25 flight hours. To request Dynon-provided kits, fill out and submit the following form: Beechcraft Series 36 Service Bulletin Request Form. This action must be performed by an appropriately-rated certified mechanic and must be entered into the aircraft records showing compliance with this service bulletin in accordance with 14 CFR 43.9(a) and the instructions in this service bulletin. The record must be maintained as required by 14 CFR 91.417. 1. Disconnect aircraft power. 2. Access pitch/yaw servo installation by removing the access panel located behind baggage area in accordance with manufacturer's service manual. 3. If implementing only the Bracket Assembly Brace Attachment Fix, unfasten and remove existing bracket assembly braces (see Figure 4), and then skip to Steps 21-22. Figure 3: Unfastening Bracket Assembly Braces 4. If implementing both fixes, disconnect wire harness connector from the yaw servo, and then complete the remaining steps. 5. Unfasten bracket assembly braces, bridge bracket, and boxing plate, as shown in Figure 4. Keep bracket assembly hardware for re-installation. Figure 4: Unfastening Bracket Assembly Braces, Bridge Bracket, and /Boxing Plate. 6. Loosen, but do not remove, cable clamps to disconnect bridle cable from the rudder control cables. 7. Remove bracket assembly, with yaw servo attached, from aircraft. 8. Remove bridle cable and capstan from the yaw servo (see Figure 5). DO NOT loosen or remove the shear screw from the servo disc! Figure 5: Removing Bridle Cable and Capstan from Yaw Servo 9. On a workbench, separate boxing plate from bridge bracket, and then drill out rivets and remove nutplate and hardware, as shown in Figure 6. Figure 6: Removing Nutplate from Boxing Plate 10. Re-attach boxing plate to bridge bracket. Torque fasteners per specifications in AC 43.13-1B, Table 7-1. 11. Position and clamp roller bracket in place, as shown Figure 7, and then drill holes through the brackets (see Figure 7). Figure 7: Positioning and Drilling Holes in Brackets 12. Attach roller bracket to bracket assembly, as shown in Figure 8. Figure 8: Attaching Roller Bracket to Bracket Assembly 13. Install roller, as shown in Figure 9. Figure 9: Installing Roller 14. Finger-tighten castle nut onto roller bolt, and then use a wrench to tighten until a slot in castle nut lines up with hole for cotter pin. DO NOT overtighten the castle nut! 15. Verify that roller moves freely and use a feeler gauge to ensure a gap between roller and bracket of at least 0.005". An overtightened castle nut may prevent the roller from moving freely! 16. Insert swage pin on new bridle cable into new capstan's engagement hole (see Figure 10). 17. Starting from engagement hole, wrap one end of bridle cable clockwise 1-1/4 times around capstan, and then wrap other end of bridle cable counterclockwise 1-1/4 times around capstan (see Figure 10). 18. Secure (e.g., tape) bridle cable to capstan grooves to prevent unraveling. 19. Temporarily attach capstan to the yaw servo (see Figure 10). Do not fully tighten castle nut or insert cotter pin yet. Figure 10: Attaching Capstan with Bridle Cable to Yaw Servo 20. Ensure capstan is positioned so: • It is fully seated on servo disc. • The orientation mark faces servo disc. • The swage engagement hole points forward. • The shear screw head is within its hole on the capstan. 21. Using provided templates, mark centerlines on gussets and stringers, as shown in Figure 11. Figure 11: Marking Centerlines on Gussets and Stingers 22. Temporarily fasten gussets to stringers, as shown in Figure 12. The upper stringer template is disposable and may be drilled through when match drilling stringer Figure 12: Temporarily Fastening Gussets to Stringers 23. Attach gussets to FS207 frame (see Figure 13), and then remove temporary fasteners and attach gussets to stringers. Do not fully tighten hardware yet. Figure 13: Attaching Gussets to Frame and Stringers (Right Side Shown)