{"id":"F2006B09699","name":"AD/F27/132 - Truss Member/Rib Attachment Bolts","slug":"ad-f27-132-truss-member-rib-attachment-bolts","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115860,"registerId":"commonwealth-F2006B09699-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F27/132 - Truss Member/Rib Attachment Bolts","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 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Fokker F27 Series Aeroplanes\n\n \n\nAD/F27/132 Truss Member/Rib Attachment Bolts 4/92\n\nApplicability: Model F27 Series, if in Pre SB F27/57-25 configuration. Requirement:  Action in accordance with Fokker SB F27/57-25 Revision 1.\n\nNote: RLD AD 91-110 refers.\n\n \n\nCompliance: Prior to 1 January 1995.\n\n \n\nBackground:  At present the truss-members at designated wing stations are attached with one long bolt at each end. To obtain a better clamping effect this bolt is replaced by two short ones. The new bolts also have a longer service life.\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":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The directive changes the hardware and maintenance requirement for affected truss-member attachments: it replaces the previous configuration of a single long bolt at each end with a mandated retrofit to two short bolts per end. The AD applies only to Model F27 Series aircraft that remain in the pre-Service-Bulletin configuration and imposes a compulsory completion date (Applicability, Requirement, Compliance, Background)."},"complexity_factors":["Narrow technical scope limited to a specific airframe model and configuration (Applicability).","Mandatory compliance by a fixed deadline creates a time-bound operational requirement (Compliance).","The AD references an external technical document (Fokker SB F27/57-25 Revision 1) for procedures and parts, requiring implementers to obtain and follow that bulletin (Requirement).","The change is mechanical and straightforward (bolt replacement), but requires parts procurement and maintenance resources (Background, Requirement).","The AD text does not describe enforcement mechanisms or supply arrangements, leaving those implementation details to operators and regulators (Compliance, Requirement)."],"plain_english_summary":"Mandates Fokker F27 aircraft that haven't had Service Bulletin F27/57-25 applied to replace a single long wing‑truss attachment bolt with two shorter bolts per truss, carried out in accordance with Fokker SB F27/57-25 Revision 1, to be completed before 1 January 1995. Owners/operators must arrange parts and labour; the change is intended to improve clamping at truss attachments and extend bolt service life, creating a time‑bound retrofit demand while the Service Bulletin provides the technical method."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in a specific aircraft type. It has not expanded beyond its original purpose of mandating a bolt replacement to improve wing structural integrity."},"complexity_factors":["Single, specific technical requirement (bolt replacement)","Only one defined applicability criterion (aircraft model and pre-modification status)","No nested exceptions or conditional logic","No cross-references to other legislation (only references a manufacturer service bulletin and a Dutch aviation authority document)","Extremely short document (under 200 words of substantive content)","Clear, single compliance deadline"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:**\nIt requires owners or operators of **Fokker F27 series aircraft** to replace specific bolts in the wing structure. Specifically, the long bolts that attach truss-members (structural supports) to wing ribs at certain points must be swapped out for two shorter bolts at each end.\n\n**Who it affects:**\nAnyone operating a Fokker F27 aircraft that hasn't already been modified according to **Service Bulletin F27/57-25** (that's what \"Pre SB F27/57-25 configuration\" means — aircraft that haven't had this fix yet).\n\n**Why it matters:**\nThe old single-bolt design didn't clamp the parts together tightly enough, and the bolts wore out faster. The new two-bolt arrangement provides better clamping force and lasts longer — reducing the risk of structural failure in the wing.\n\n**What had to happen:**\nOperators had to complete this modification **before 1 January 1995**.\n\n**Key terms explained:**\n- **Service Bulletin (SB):** A manufacturer's official instruction for fixing or improving an aircraft design.\n- **Truss-member/rib:** Parts of the aircraft's internal wing structure — the ribs are like the wing's skeleton, and truss-members are supporting struts.\n- **Airworthiness Directive:** A legally enforceable safety rule; ignoring it means the aircraft isn't allowed to fly."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f27-132-truss-member-rib-attachment-bolts","history":"/api/acts/ad-f27-132-truss-member-rib-attachment-bolts/history","analysis":"/api/acts/ad-f27-132-truss-member-rib-attachment-bolts/analysis","conflicts":"/api/acts/ad-f27-132-truss-member-rib-attachment-bolts/conflicts","importantCases":"/api/acts/ad-f27-132-truss-member-rib-attachment-bolts/important-cases","documents":"/api/acts/ad-f27-132-truss-member-rib-attachment-bolts/documents"}}