{"id":"F2006B06946","name":"AD/SF340/18 - Nacelle Drag Strut Bolts, Lower Fittings and Attaching Fasteners","slug":"ad-sf340-18-nacelle-drag-strut-bolts-lower-fittings-and-attaching-fasteners","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114843,"registerId":"commonwealth-F2006B06946-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/SF340/18 - Nacelle Drag Strut Bolts, Lower Fittings and Attaching Fasteners","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)  SAAB SF340 Series Aeroplanes\n\n \n\nAD/SF340/18 Nacelle Drag Strut Bolts, Lower Fittings\n\nand Attaching Fasteners\n\nApplicability: SF340A S/No -004 to -159 SF340B S/No -160 to 166. Requirement:  Action in accordance with SAAB Service Bulletin 340-54-026.\n\nNote: Swedish AD 1-034 refers.\n\n \n\nCompliance: 1. Para 2B (1) to (4); within 200 hours time in service after 15 January 1990.\n\n\n3/90\n\nDM\n\n \n\n2. Para 2B (5); at the next engine removal or within 1500 hours time in service after 15 January 1990.\n\n \n\nBackground:  There have been reports of loose nuts at the lower drag strut support fitting. If not corrected could, in the case of a double failure, result in the loss of structural integrity of the power plant installation.\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 addressing a specific mechanical defect in a specific aircraft type. It has not expanded beyond its original purpose of ensuring structural integrity of engine installations on SAAB SF340 series aircraft."},"complexity_factors":["Very short document (approximately 150 words of substantive content)","Only 2 defined applicability criteria (aircraft serial number ranges)","Simple two-stage compliance structure with clear time-based triggers","Single cross-reference to SAAB Service Bulletin (external technical document, not legislative cross-reference)","No nested conditions, exceptions, or definitional sections","Straightforward causal chain: reported defect → mandated inspection → specified timeframe"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order for aircraft owners and operators.\n\n**What it does:**\nOrders inspections and repairs on specific bolts and fittings in the engine nacelles (the housings around the engines) of SAAB SF340 aircraft. These parts are called \"drag strut bolts, lower fittings and attaching fasteners\" — they're structural components that help hold the engine in place.\n\n**Who it affects:**\nOperators of SAAB SF340A aircraft (serial numbers -004 to -159) and SF340B aircraft (serial numbers -160 to 166).\n\n**Why it matters:**\nThere were reports of loose nuts on these fittings. If two of these failed at once (a \"double failure\"), the engine could literally fall off the wing. This directive prevents that catastrophic outcome by requiring specific maintenance actions outlined in SAAB Service Bulletin 340-54-026.\n\n**What must be done:**\n- **First part:** Inspections and immediate fixes within 200 flight hours after 15 January 1990\n- **Second part:** Additional work at the next engine removal or within 1,500 flight hours after 15 January 1990\n\n**Key point:** This is a **retrospective directive** — it applies to aircraft already in service and mandates specific maintenance windows based on flight hours accumulated after a fixed date."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD addresses loose nuts at the lower drag strut support fitting for the listed SF340 serial numbers and prescribes corrective action per the SAAB service bulletin with specific compliance times. The instrument does not indicate any expansion or narrowing of that original corrective scope; it stays focused on inspection/repair of the specified fittings (Applicability, Requirement, Compliance, Background)."},"complexity_factors":["Narrow applicability by serial number list increases admin work for operators to confirm coverage (Applicability).","Action is specified by reference to an external document (SAAB Service Bulletin 340-54-026), creating a dependency on that bulletin for technical detail (Requirement).","Two distinct compliance deadlines (short 200-hour window and longer 1500-hour/next-engine-removal option) require scheduling and record-keeping (Compliance: Para 2B(1)–(4) and Para 2B(5)).","Safety-critical consequence (loss of powerplant installation integrity on double failure) raises enforcement priority and potential for mandatory corrective action (Background).","Cross-reference to a foreign airworthiness directive (Swedish AD 1-034) means operators may need to reconcile multiple directives."],"plain_english_summary":"Applies to SAAB SF340A (S/No -004 to -159) and SF340B (S/No -160 to -166). It requires operators to follow SAAB Service Bulletin 340-54-026 to inspect and secure nacelle drag strut lower fittings and attaching fasteners (Requirement). Compliance deadlines: Para 2B(1)–(4) within 200 hours time-in-service after 15 January 1990; Para 2B(5) at the next engine removal or within 1500 hours TIS (Compliance). The directive responds to reports of loose nuts that could, on a double failure, compromise the powerplant installation (Background)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-sf340-18-nacelle-drag-strut-bolts-lower-fittings-and-attaching-fasteners","history":"/api/acts/ad-sf340-18-nacelle-drag-strut-bolts-lower-fittings-and-attaching-fasteners/history","analysis":"/api/acts/ad-sf340-18-nacelle-drag-strut-bolts-lower-fittings-and-attaching-fasteners/analysis","conflicts":"/api/acts/ad-sf340-18-nacelle-drag-strut-bolts-lower-fittings-and-attaching-fasteners/conflicts","importantCases":"/api/acts/ad-sf340-18-nacelle-drag-strut-bolts-lower-fittings-and-attaching-fasteners/important-cases","documents":"/api/acts/ad-sf340-18-nacelle-drag-strut-bolts-lower-fittings-and-attaching-fasteners/documents"}}