{"id":"F2006B03236","name":"AD/B747/55 - Nacelle Strut Attachment Fitting Bolts","slug":"ad-b747-55-nacelle-strut-attachment-fitting-bolts","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42660,"registerId":"commonwealth-F2006B03236-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/55 - Nacelle Strut Attachment Fitting 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)  Boeing 747 Series Aeroplanes\n\n \n\nAD/B747/55 Nacelle Strut Attachment Fitting Bolts 1/87\n\nApplicability: All models with line numbers 1 to 644.\n\n \n\nRequirement: Action in accordance with Para’s A,B,C,D,E & F of FAA AD 86-23-01.\n\n \n\nNote: Boeing SB 747-57A2235 refers.\n\n \n\nCompliance: As per Requirement Document from 31 January 1987.\n\n \n\nBackground: The manufacturer reports of fractured H-11 bolts which secure the nacelle strut attachment fittings. One instance reported was of both bolts fractured at one fitting.\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\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue safety directive focused specifically on H-11 bolt failures in nacelle strut attachments. It has not expanded beyond its original purpose; it addresses one identified airworthiness concern with a clear remedy and deadline."},"complexity_factors":["Extremely short document — approximately 150 words of substantive content","No defined terms section; all language is plain technical aviation terminology","Single cross-reference to an external FAA document (AD 86-23-01) for actual technical requirements","No conditional logic, exceptions, or nested provisions","Simple structure: applicability → requirement → compliance date → background","Incorporates technical requirements by reference rather than setting them out in full"],"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 \"recall notice\" for aircraft, but legally binding.\n\n**What it does:** It requires owners and operators of specific Boeing 747 aircraft to inspect and fix a dangerous problem with bolts that hold the engine nacelle (the housing around the engine) to the wing strut.\n\n**The problem:** The manufacturer found that H-11 steel bolts were cracking and breaking. In one scary case, *both* bolts at one attachment point snapped. If these bolts fail, the engine could detach from the wing.\n\n**Who must act:** Anyone operating Boeing 747s with \"line numbers\" (manufacturing serial numbers) 1 through 644 — essentially the early production models.\n\n**What they must do:** Follow the specific inspection and replacement procedures laid out in the US Federal Aviation Administration's AD 86-23-01, paragraphs A through F. Boeing Service Bulletin 747-57A2235 provides the technical instructions.\n\n**When:** By 31 January 1987.\n\n**Why it matters:** This prevents catastrophic engine separation. Airworthiness directives are the aviation safety net — they turn manufacturer warnings into legal obligations."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The directive applies to all Boeing 747 models with line numbers 1–644 and requires compliance with specific paragraphs of FAA AD 86-23-01. The source text contains no amendment language or indications that the scope has changed from the original intent as stated in the document. The stated purpose (response to fractured H‑11 bolts) and the required mechanical action (follow FAA AD paras A–F) are consistent within the document."},"complexity_factors":["Cross-reference to an external FAA AD (paras A–F of FAA AD 86-23-01) rather than containing full standalone procedures (Requirement)","Reference to manufacturer service bulletin for technical details (Boeing SB 747-57A2235) (Note)","Safety-critical part (H‑11 bolts on nacelle strut attachment fittings) where failure consequences are significant (Background)","Applicability limited to specific line-number range (1–644) requiring accurate aircraft identification (Applicability)","Compliance is time-bound from a past date, requiring retrospective or ongoing actions and record-keeping (Compliance)","Operational impact: inspections and corrective work cause aircraft downtime, parts procurement and labour scheduling (Requirement; Compliance)","Limited regulatory discretion in deviation from the referenced FAA AD increases procedural strictness (Requirement)","Potential ambiguity or implementation risk if the referenced FAA AD or Boeing SB is updated, interpreted differently, or unavailable (Requirement; Note)"],"plain_english_summary":"This AD requires operators of Boeing 747s (line numbers 1–644) to carry out the inspections and corrective actions specified in FAA AD 86‑23‑01—prompted by reports of fractured H‑11 bolts at nacelle strut fittings—and references Boeing SB 747‑57A2235 for technical guidance.  \n\nCompliance has been mandatory since 31 January 1987; aircraft owners/operators must schedule, fund and complete inspections, repairs and any associated downtime."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-55-nacelle-strut-attachment-fitting-bolts","history":"/api/acts/ad-b747-55-nacelle-strut-attachment-fitting-bolts/history","analysis":"/api/acts/ad-b747-55-nacelle-strut-attachment-fitting-bolts/analysis","conflicts":"/api/acts/ad-b747-55-nacelle-strut-attachment-fitting-bolts/conflicts","importantCases":"/api/acts/ad-b747-55-nacelle-strut-attachment-fitting-bolts/important-cases","documents":"/api/acts/ad-b747-55-nacelle-strut-attachment-fitting-bolts/documents"}}