{"id":"F2006B02076","name":"AD/AC/17A - Landing Gear Truss Attach Angle - Inspection","slug":"ad-ac-17a-landing-gear-truss-attach-angle-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41306,"registerId":"commonwealth-F2006B02076-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AC/17A - Landing Gear Truss Attach Angle - Inspection","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-description: CASA Airworthiness Directive\nmeta-generator: Aspose.Words for .NET 22.10.0\nmeta-keywords: Issue 12/1967,Aircraft below 5700 kg,Twin Commander (Gulfstream/Rockwell/ Aerocommander 500, 600 and 700) Series Aeroplanes,Landing Gear Truss Attach Angle - Inspection,17A\ntitle: Airworthiness Directive - AD/AC/17A - Landing Gear Truss Attach Angle - Inspection\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Twin Commander (Gulfstream/Rockwell/ Aerocommander 500, 600 and 700) Series Aeroplanes\n\n \n\nAD/AC/17A Landing Gear Truss Attach Angle - Inspection 12/67\n\nApplicability: All models: S/Nos. 231 to 892 except 875. Document: Aero Commander SL No. 77A.\n\nCompliance: At intervals not exceeding 1000 hours’ time in service.\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\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a classic, narrow Airworthiness Directive from 1967 (Issue 12/1967). It addresses a specific mechanical defect in a specific aircraft type with a specific inspection interval. There is no evidence of scope creep — it does exactly what it says on the tin and nothing more."},"complexity_factors":["Extremely short document — only 4 substantive lines of regulatory text","Single, unambiguous compliance requirement (inspect every 1000 hours)","No defined terms section — all language is plain technical English","No cross-references to other legislation beyond the enabling regulation (CAR 1998 Part 39)","Simple applicability criteria (serial number range with one exclusion)","No conditional logic, exceptions to exceptions, or nested provisions","References only one external technical document (manufacturer's service letter)"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). Think of it as a compulsory recall notice for aircraft, but instead of fixing cars, it fixes planes.\n\n**What it requires:** Owners and operators of specific Twin Commander aircraft (models 500, 600, and 700 series) must inspect the \"landing gear truss attach angle\" — a metal bracket that connects the landing gear strut to the aircraft's frame. This inspection must happen **every 1,000 hours of flight time**.\n\n**Who it affects:** Anyone who owns or operates the affected Twin Commander planes with serial numbers 231 to 892 (except serial number 875). These are small twin-engine aircraft typically used for private flying, charter work, or corporate transport.\n\n**Why it matters:** The landing gear truss attach angle is critical — if it fails, the landing gear could collapse during takeoff or landing. This AD ensures potential cracks or wear get caught before they cause accidents. The reference to \"Aero Commander SL No. 77A\" points to the manufacturer's original service bulletin that identified the problem.\n\n**The bottom line:** If you fly one of these planes, you must check this specific part regularly. No exceptions, no delays — it's the law."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The instrument itself sets a focused scope: mandatory inspection of the landing gear truss attach angle for Twin Commander aeroplanes with serial numbers 231–892 except 875, at intervals not exceeding 1,000 hours TIS, and references Aero Commander SL No. 77A. The text contains no indication that its scope amends or broadens a prior instrument; it is a standalone directive that narrows applicability by serial number and prescribes a fixed inspection interval."},"complexity_factors":["Narrow, clearly defined applicability by serial number (S/N 231–892 except 875) reduces ambiguity.","Single, simple compliance requirement (inspection) with a single recurring interval (<= 1,000 hours TIS).","Procedural specifics are delegated to an external document (Aero Commander SL No. 77A), creating a dependency on that document for technical detail.","No multiple conditional schedules, exceptions, or complex approval pathways present in the text.","Regulatory context is explicit (issued under Civil Aviation Regulations, Part 39), which sets enforcement framework but is not expanded in the text.","Missing details on corrective action, recordkeeping format, and cost estimates—operators must consult other documents/practice for those aspects."],"plain_english_summary":"What this instrument does mechanically\n\n- This is an Airworthiness Directive (AD) issued under the Commonwealth Civil Aviation framework (header: \"Civil Aviation Regulations 1998, PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\"). It requires a specific inspection of an aircraft component: the landing gear truss attach angle. (Header and title; “AD/AC/17A Landing Gear Truss Attach Angle - Inspection”.)\n\n- Applicability is limited to Twin Commander (Gulfstream/Rockwell/Aerocommander 500, 600 and 700) series aeroplanes with serial numbers 231 through 892, except serial number 875. (See “Applicability: All models: S/Nos. 231 to 892 except 875.”)\n\n- The inspection must be performed in accordance with Aero Commander Service Letter No. 77A (the document referenced). (See “Document: Aero Commander SL No. 77A.”)\n\n- The inspection frequency is prescribed as at intervals not exceeding 1,000 hours’ time in service. Operators must therefore inspect each affected aeroplane at least every 1,000 hours TIS. (See “Compliance: At intervals not exceeding 1000 hours’ time in service.”)\n\nWho this affects and who decides\n\n- Directly affected: owners and operators of the listed Twin Commander aeroplanes (S/N 231–892, except 875). They are the parties who must arrange and pay for inspections. (Applicability and Compliance.)\n\n- Who sets the requirement: the Civil Aviation Safety Authority (CASA) is the issuing authority as indicated in the header. The directive refers operators to a manufacturer document (Aero Commander SL No. 77A) for the inspection procedure. (Header; Document.)\n\n- Who performs the work: operators will have to use their own maintenance personnel or contract independent/approved maintenance organisations to carry out the inspection according to the referenced service letter.\n\nWhy it matters (stated purpose and practical trade-offs)\n\n- The instrument is presented as an Airworthiness Directive, i.e. a mandatory safety-related inspection requirement. That framing implies the directive’s purpose is to manage a risk to structural integrity or safe operation of the landing gear attach area. (Header and title.)\n\n- Trade-offs and costs implicit in the requirement:\n  - Operators incur direct costs: labour, possible replacement parts, and aircraft downtime whenever the inspection is done (Compliance: 1,000 hours interval). The source text does not quantify those costs.\n  - There is an administrative compliance burden: scheduling inspections every 1,000 hours TIS and retaining records to show compliance. (Compliance.)\n  - The directive ties compliance to a manufacturer service letter (Aero Commander SL No. 77A). That centralises the technical method to a single referenced document; operators must follow that document to meet the AD. (Document.)\n\n- Implementation and discretion:\n  - CASA issues the AD; enforcement and oversight are done under the Civil Aviation regulatory framework referenced in the header. The AD itself defines applicability and the inspection interval; it relies on the referenced service letter for procedural detail. (Header; Applicability; Compliance; Document.)\n\nMechanisms that change behaviour and incentives\n\n- Operators must schedule recurring inspections at intervals not exceeding 1,000 hours TIS for the specified serial-numbered aeroplanes. This changes maintenance planning and operating costs for affected aircraft. (Compliance; Applicability.)\n\n- The reliance on Aero Commander SL No. 77A means that compliance is measured against that manufacturer-provided procedure; operators who do not follow that procedure will not satisfy the AD. (Document.)\n\nConcrete consequences (mechanical, not normative)\n\n- Who pays: aircraft owners/operators pay for the inspections and any follow-up work (inferred from mandatory inspection requirement and standard practice; see Compliance and Applicability).\n\n- Who decides on method: CASA requires the inspection and points to Aero Commander SL No. 77A for the method. Operational choices (scheduling, selection of maintenance provider) remain with the operator, constrained by the need to meet the AD and the referenced service letter. (Header; Document; Compliance.)\n\n- Compliance burden: recurring interval-based inspections add recurring time-out-of-service and recordkeeping obligations. (Compliance.)\n\n- Market effects: the AD is narrowly targeted by serial number and part; it therefore concentrates obligations on a defined subset of owners/operators. The text does not itself create subsidies, exemptions, or new certification pathways. (Applicability; Compliance.)\n\nLimitations of this analysis\n\n- The AD text is short and prescriptive. It references Aero Commander SL No. 77A for procedural detail; that referenced document contains the operative inspection steps and any acceptance criteria, which this summary does not reproduce. (Document.)\n\n- The AD does not state estimated costs, specific corrective actions if the inspection finds a defect, or enforcement penalties. Those operational details sit in enforcement practice and the referenced service letter.\n"}},"importantCases":[],"_links":{"self":"/api/acts/ad-ac-17a-landing-gear-truss-attach-angle-inspection","history":"/api/acts/ad-ac-17a-landing-gear-truss-attach-angle-inspection/history","analysis":"/api/acts/ad-ac-17a-landing-gear-truss-attach-angle-inspection/analysis","conflicts":"/api/acts/ad-ac-17a-landing-gear-truss-attach-angle-inspection/conflicts","importantCases":"/api/acts/ad-ac-17a-landing-gear-truss-attach-angle-inspection/important-cases","documents":"/api/acts/ad-ac-17a-landing-gear-truss-attach-angle-inspection/documents"}}