Mandatory Service Bulletin - Kit for STC SA011869WI

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MANDATORY SERVICE BULLETIN Original Issue: 23 May 2025 Reference: MFSBM-2501 Rev 00 Page 1 of 6 Middle Fork Mods LLC  P.O. Box 346  Challis, ID 83226 (208) 879-6637  mfm@custertel.net  middleforkmods.com TITLE Mandatory Service Bulletin - Kit for STC SA011869WI PURPOSE This Mandatory Service Bulletin informs operators of a potential safety issue and provides instructions to minimize probability of an unsafe failure condition. This Mandatory Service Bulletin supersedes the previously issued Alert Service Bulletin MFSBA-2501 (Ref [5]). EFFECTIVITY • Textron Aviation Inc. 172 and 175 model aircraft that have been modified in accordance with STC SA01869WI, Middle Fork Mods LLC Tail Tie Down Assembly 16-020-534530, Middle Fork Mods LLC Serial Numbers 1 through 140 • The complete applicable aircraft model list is detailed in FAA Supplemental Type Certificate SA01869WI. REASON There is a potential safety issue regarding the installation of the Tail Tie-Down Assembly interference with the rudder control cable. Two incidents have been reported in which the installation of this modification results in the rudder control cable contacting a fairing screw installed by this Kit. This condition could result in severance or fraying of the cables with loss of rudder control. Figure 1 identifies the area in question. Figure 1: Affected Area Tailcone Fairing (removed) Reported Contact Location with Rudder Control Cable F W D Tailcone Fairing Forward AN526632R8 Screw with Demonstrated Contact with Rudder Control Cable MANDATORY SERVICE BULLETIN Original Issue: 23 May 2025 Reference: MFSBM-2501 Rev 00 Page 2 of 6 Middle Fork Mods LLC  P.O. Box 346  Challis, ID 83226 (208) 879-6637  mfm@custertel.net  middleforkmods.com COMPLIANCE Compliance with this Mandatory Service Bulletin must be accomplished to correct the potential safety issue. Document Mandatory Service Bulletin compliance as a written entry in the applicable aircraft logbook. A service document published by Middle Fork Mods may be recorded as completed in an aircraft logbook only when the following requirements are satisfied: 1. The mechanic must complete all the instructions in the service document, including the intent therein. 2. The mechanic or airplane owner must use the technical data in the service document only as approved and published. 3. The mechanic or airplane owner must apply the information in the service document only to aircraft identified in the Effectivity section of the document. 4. The mechanic or airplane owner must use maintenance practices that are identified as acceptable standard practices in the aviation industry and governmental regulations. Accomplishment of these tasks should be performed at the next scheduled inspection after receipt of this Mandatory Service Bulletin, but no later than the next 16 flight hours. Refer to the Modification Instructions (16-020-AE3302 Rev 01, Ref [4]) as required. REFERENCES [1] Federal Aviation Administration. Department of Transportation. Supplemental Type Certificate Number SA01869WI. [2] Federal Aviation Administration. Advisory Circular. AC 43.13-2B. “Acceptable Methods, Techniques, and Practices – Aircraft Alterations.” [3] Applicable Textron/Cessna Aircraft Maintenance Manual (AMM) [4] Middle Fork Mods. Modification Instructions. 16-020-AE3302 Rev 01. “Tail Tie-Down Replacement.” [5] Middle Fork Mods. Alert Service Bulletin. MFSBA-2501 Rev 00. [6] Middle Fork Mods. Instructions for Continued Airworthiness. 16-020-MT2901 Rev 04. NOTE: The modification instructions (Ref [4]) and instructions for continued airworthiness (Ref [6]) have been updated to reflect the changes presented in this Mandatory Service Bulletin. MANDATORY SERVICE BULLETIN Original Issue: 23 May 2025 Reference: MFSBM-2501 Rev 00 Page 3 of 6 Middle Fork Mods LLC  P.O. Box 346  Challis, ID 83226 (208) 879-6637  mfm@custertel.net  middleforkmods.com DESCRIPTION Rudder control cable assemblies shall be inspected for separation, broken wires, fraying of cables and wear. Inspect the rudder flight control cable installation to see if any damage or changes exist outside the modifications introduced by this Kit that would change the location of the rudder control cable. Worn or damaged rudder control cables shall be replaced. The tail cone fairing installation shall be updated as per this Mandatory Service Bulletin, to also align with the same process in the updated modification instructions (Ref [4]). There shall be positive clearance between any item on the aircraft and the rudder control cable. SAFETY INTENT For aircraft with the Middle Fork Mods LLC Tail Tie Down Assembly 16-020-534530 installed, the intent is to avoid inadvertent rudder control cable contact. TOOLS AND TECHNICAL DATA • Middle Fork Mods LLC Modification Instructions Document No: 16-020-AE3302 Rev 01 (Ref [4]) • Phillips # 2 screwdriver • Mirror and flashlight • #40 drill bit and drill PERSONNEL REQUIREMENTS • One individual that holds an Airframe and Powerplant Mechanic license • One helper MANDATORY SERVICE BULLETIN Original Issue: 23 May 2025 Reference: MFSBM-2501 Rev 00 Page 4 of 6 Middle Fork Mods LLC  P.O. Box 346  Challis, ID 83226 (208) 879-6637  mfm@custertel.net  middleforkmods.com ACCOMPLISHMENT INSTRUCTIONS (1) Reference 16-020-AE3302 Rev 01 (Ref [4]) page 3-17, figure 3-19, “Tail cone Faring, Installed.” (2) Remove 9x AN526632R8 screws and fairing with #2 Phillips screwdriver. Figure 2: Screws to Remove (3) Inspect rudder cable in the vicinity of the Tail Tie Down Assembly 16-020-534530. (a) If no wear or damage is observed on the rudder control cable at the location of the Kit screws and nutplates, no further action is required regarding the rudder control cable. (b) If any wear or damage is observed on the rudder control cable at the location of the Kit screws and nutplates, replace the rudder control cable following approved guidance of the applicable Textron/Cessna AMM or FAA AC 43.13-1B. MANDATORY