{"id":"F2006B04672","name":"AD/BELL 412/38 - Hydraulic Servo Actuator Shoulder Bolt","slug":"ad-bell-412-38-hydraulic-servo-actuator-shoulder-bolt","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44424,"registerId":"commonwealth-F2006B04672-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 412/38 - Hydraulic Servo Actuator Shoulder Bolt","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nBell Helicopter Textron 412 Series Helicopters\n\nAD/BELL 412/38 Hydraulic Servo Actuator Shoulder Bolt 13/95\n\nApplicability: All Bell Helicopter Textron 412 Series Helicopters S/N 33001 through 33213, 36001\n\nthrough 36104 and 34001 through 34024, 46400 through 46408 which have servos installed which have been overhauled or repaired by a facility not approved by HR Textron.\n\nRequirement: Unless previously carried out, action in accordance with Bell ASB 412-95-86. Compliance: Within 25 hours time in service from 7 December 1995 or by 31 January 1996,\n\nwhichever occurs first.\n\nBackground: Bell Textron has advised that unauthorised rework/repair of the shoulder bolts may have been carried out. An inspection of the shoulder bolts for possible unauthorised chrome plating is required.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive addressing a specific manufacturing defect/repair issue. It has not expanded beyond its original purpose of ensuring shoulder bolt integrity on affected helicopters."},"complexity_factors":["Single, specific mechanical component (shoulder bolt) addressed","Narrow applicability criteria (specific serial number ranges plus specific repair history)","No defined terms section — uses standard aviation terminology","Single compliance action with clear deadline","No cross-references to other legislation beyond the parent Civil Aviation Regulations","Background explanation provided in plain language"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — essentially a mandatory safety notice issued by Australia's Civil Aviation Safety Authority (CASA) for specific Bell 412 helicopters.\n\n**What it does:** It requires owners and operators of certain Bell 412 helicopters to inspect a specific part called a \"shoulder bolt\" in the hydraulic servo actuator (a component that helps control the helicopter's flight). The inspection checks whether someone improperly applied chrome plating to these bolts during unauthorized repairs.\n\n**Who it affects:** Owners and operators of Bell 412 helicopters with serial numbers 33001-33213, 36001-36104, 34001-34024, and 46400-46408 — but only if their servo actuators were overhauled or repaired by a facility NOT approved by HR Textron (the manufacturer).\n\n**Why it matters:** Unauthorized chrome plating on these bolts can weaken them or cause them to fail. If a shoulder bolt fails in flight, the pilot could lose control of the helicopter. This directive prevents potential catastrophic accidents by catching bad repairs before they cause harm.\n\n**What must be done:** Follow the instructions in Bell Alert Service Bulletin 412-95-86 to inspect the bolts. This must be completed within 25 flight hours after 7 December 1995, or by 31 January 1996 — whichever comes first."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive confines its scope to specific Bell 412 airframes (by serial number) and to servos overhauled or repaired by non‑HR Textron approved facilities, and requires a single inspection action per the Bell service bulletin within a short, specified time. The text does not expand the set of affected components, the required action, or the compliance conditions beyond those elements; therefore the scope remains aligned with the instrument's expressed purpose (detecting possible unauthorised rework of shoulder bolts). (Applicability; Requirement; Compliance; Background)"},"complexity_factors":["Limited applicability to specific helicopter serial numbers (reduces scope of affected population) (Applicability)","Single technical action mandated (inspection for unauthorised chrome plating) referenced to an external service bulletin (Bell ASB 412-95-86) (Requirement)","Short and fixed compliance timeframe (25 hours TIS from 7 Dec 1995 or by 31 Jan 1996) creates scheduling pressure (Compliance)","Need to determine repair provenance (whether servo was overhauled by a non‑approved facility) imposes administrative/record‑checking steps (Applicability)","Potential for follow‑on corrective work if inspection finds unauthorised plating, which could add variability to actual workload and cost (Requirement)","Regulatory dependency on an external manufacturer service bulletin for procedural detail (Requirement)"],"plain_english_summary":"What the rule does (mechanics)\n\n- Requires an inspection of the hydraulic servo actuator shoulder bolts on certain Bell Helicopter Textron 412 series helicopters to check for possible unauthorised chrome plating. The inspection must be done in accordance with Bell Service Bulletin ASB 412-95-86. (Requirement; Background)\n- Applies only to specified airframes by serial number where servos have been overhauled or repaired by a facility not approved by HR Textron. (Applicability)\n- Sets a short compliance window: within 25 hours time in service from 7 December 1995 or by 31 January 1996, whichever is earlier; if the inspection has already been carried out, no further action is required. (Compliance; Requirement)\n\nWho this affects\n\n- Operators and owners of the listed Bell 412 helicopters (by serial number) whose servos were overhauled or repaired by non‑HR Textron approved facilities. (Applicability)\n- Maintenance organisations and mechanics who must perform the inspection and any corrective work dictated by Bell ASB 412-95-86. (Requirement)\n- Repair facilities: the directive targets servos that were overhauled by non‑approved facilities and therefore creates an operational incentive for operators to use HR Textron‑approved repairers in the future. (Applicability; Background)\n\nWhy it matters (official rationale and practical consequences)\n\n- Officially, Bell Textron advised that unauthorised rework or repair of the shoulder bolts may have occurred; the inspection seeks to detect unauthorised chrome plating that could affect component integrity. (Background)\n- Concretely, the directive transfers the immediate costs of inspection and any follow‑on corrective work to the affected aircraft operators and their maintenance providers, and imposes a short scheduling constraint (25 hours TIS or a fixed calendar deadline). (Requirement; Compliance)\n\nCosts, incentives and trade‑offs (practical testing of the stated purpose)\n\n- Who pays: Operators bear inspection and any repair costs, plus the cost of aircraft downtime while work is performed. (Requirement; Compliance)\n- Who decides: The Civil Aviation Safety Authority issued the AD and mandates compliance by reference to Bell ASB 412-95-86, which specifies the technical steps. Operators choose how and where to have the inspection/repairs performed, subject to the ASB and applicable approval status of repair facilities. (Requirement; Applicability)\n- Compliance burden and administrative work: Operators must identify whether a given servo was overhauled by a non‑approved facility (record checks), arrange inspections within a short window, and if defects are found, follow the service bulletin instructions for corrective action. (Applicability; Compliance; Requirement)\n- Effect on repair market and private choice: By singling out servos overhauled by non‑HR Textron approved facilities, the directive creates an operational incentive for operators to use approved repairers for future overhauls to avoid additional inspections or corrective work tied to unapproved repairs. (Applicability; Background)\n- Implementation risks and opportunity costs: The short compliance period concentrates logistical effort into a limited time; operators may need to reschedule flights, divert maintenance slots, or incur premium labour/transport costs to meet the deadline. (Compliance)\n\nPractical next steps for an affected operator\n\n- Check whether the aircraft serial number is listed and whether the servo was overhauled or repaired by a non‑HR Textron approved facility. (Applicability)\n- If applicable and not already done, carry out the inspection per Bell ASB 412-95-86 within the specified compliance window. (Requirement; Compliance)\n\nCitations: Applicability; Requirement; Compliance; Background."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-412-38-hydraulic-servo-actuator-shoulder-bolt","history":"/api/acts/ad-bell-412-38-hydraulic-servo-actuator-shoulder-bolt/history","analysis":"/api/acts/ad-bell-412-38-hydraulic-servo-actuator-shoulder-bolt/analysis","conflicts":"/api/acts/ad-bell-412-38-hydraulic-servo-actuator-shoulder-bolt/conflicts","importantCases":"/api/acts/ad-bell-412-38-hydraulic-servo-actuator-shoulder-bolt/important-cases","documents":"/api/acts/ad-bell-412-38-hydraulic-servo-actuator-shoulder-bolt/documents"}}