{"id":"F2006B08672","name":"AD/CT58/14 - Lead Lag Servo Housing","slug":"ad-ct58-14-lead-lag-servo-housing","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51774,"registerId":"commonwealth-F2006B08672-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CT58/14 - Lead Lag Servo Housing","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  General Electric Turbine Engines - CT58 Series\n\n \n\nAD/CT58/14 Lead Lag Servo Housing 9/85\n\nApplicability: All CT58 model engines.\n\n \n\nDocument: General Electric SB (CT58) A73-71 Rev. 1; or AD/GE-T/36A.\n\nCompliance: As per the requirement document.\n\n \n\nBackground:  This Directive is raised in issue to reflect the latest issue of the manufacturers requirement document, which adds additional inspection procedures concerning fuel controls that contain counter bores in two of the screw holes used to retain the lead lag servo housing.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive focused on a specific mechanical component in a specific engine series. It has not expanded beyond its original purpose of ensuring airworthiness of CT58 engine fuel control systems."},"complexity_factors":["Extremely short document — only 8 substantive lines","No defined terms section — relies entirely on external manufacturer documents","Single, straightforward applicability clause ('All CT58 model engines')","No conditional logic or nested exceptions — compliance is simply 'as per the requirement document'","No cross-references to other legislation beyond citing the source Service Bulletin and a related AD","Technical content is delegated entirely to external engineering documents (the Service Bulletin)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA).\n\n**What it does:**\n- Requires owners and operators of **General Electric CT58 model turbine engines** (used in helicopters like the Sikorsky S-61) to perform specific inspections on the **lead lag servo housing** — a component that helps manage blade movement in helicopter rotors.\n- The directive updates an earlier safety requirement to include **additional inspection procedures** for fuel controls that have **counter bores** (specially shaped recesses) in two screw holes that hold the servo housing in place.\n\n**Who it affects:**\n- Anyone operating aircraft with **CT58 engines** — primarily helicopter operators, maintenance organisations, and engineers.\n\n**Why it matters:**\n- **Safety-critical:** The lead lag servo housing is vital for controlling rotor blade movement. A failure here could lead to catastrophic rotor system failure.\n- **Legally binding:** Compliance is mandatory. Operating an aircraft without meeting this directive violates civil aviation law.\n- **Updated requirements:** The directive reflects new manufacturer guidance (General Electric Service Bulletin A73-71 Rev. 1) that identified additional areas needing inspection, suggesting potential failure modes were discovered since the original directive."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"This reissued directive expands the inspection requirements by reflecting the latest issue of the manufacturer's requirement document. The change added additional inspection procedures specifically targeting fuel controls that contain counter bores in two of the screw holes used to retain the lead‑lag servo housing (Background). The instrument therefore broadens the technical focus of inspections for all CT58 engines by incorporating those new procedures, while leaving detailed methodology to the referenced GE service bulletin (Document; Compliance)."},"complexity_factors":["Cross-reference to external manufacturer's documents for all procedural detail (Document; Compliance).","Technical specificity limited to a particular part feature (fuel controls with counter bores in two screw holes) that requires component-level identification (Background).","Wide applicability (all CT58 model engines) increases administrative reach despite concise text (Applicability).","Operational interpretation burden: the directive does not restate inspection methods or intervals, requiring users to obtain and interpret the referenced service bulletin (Document).","Potential versioning issue: the directive reflects the \"latest issue\" of the manufacturer's document, so maintaining awareness of the correct revision is necessary (Background; Document)."],"plain_english_summary":"This airworthiness directive requires operators of General Electric CT58 turbine engines to perform the inspections and maintenance actions specified in the latest GE service document, reissued because that document adds procedures targeting fuel‑control components with counter bores in lead‑lag servo housing screw holes.\n\nIt affects CT58 owners/operators (who bear inspection and repair costs) and their maintenance providers; it matters because it creates a mandatory compliance obligation and may increase maintenance workload, downtime and parts replacement."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ct58-14-lead-lag-servo-housing","history":"/api/acts/ad-ct58-14-lead-lag-servo-housing/history","analysis":"/api/acts/ad-ct58-14-lead-lag-servo-housing/analysis","conflicts":"/api/acts/ad-ct58-14-lead-lag-servo-housing/conflicts","importantCases":"/api/acts/ad-ct58-14-lead-lag-servo-housing/important-cases","documents":"/api/acts/ad-ct58-14-lead-lag-servo-housing/documents"}}