{"id":"F2006B02739","name":"AD/B727/39 - Main Landing Gear Down Lock Universal Bolt - Replacement","slug":"ad-b727-39-main-landing-gear-down-lock-universal-bolt-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42081,"registerId":"commonwealth-F2006B02739-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/39 - Main Landing Gear Down Lock Universal Bolt - Replacement","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 727 Series Aeroplanes\n\n \n\nAD/B727/39 Main Landing Gear Down Lock Universal Bolt - Replacement\n\n\n3/67\n\n \n\nApplicability: All models.\n\n \n\nDocument: Boeing SB No. 32-106. Compliance: Forthwith.\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\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. Airworthiness Directives are inherently narrow in scope — each addresses a specific airworthiness concern. There is no indication this AD has expanded beyond its original purpose of addressing the identified bolt defect."},"complexity_factors":["Extremely short document — only 4 substantive lines of regulatory text","No defined terms section — uses plain technical language","No cross-references to other legislation beyond the enabling regulation (CAR 1998 Part 39)","No conditional logic or exceptions — applies universally to all models with immediate effect","Single, unambiguous compliance action (bolt replacement)","Document reference is external (Boeing SB) rather than internal cross-reference"],"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) under the Civil Aviation Regulations 1998.\n\n**What it does:** It requires the **replacement of a specific bolt** — the \"Main Landing Gear Down Lock Universal Bolt\" — on all Boeing 727 series aircraft.\n\n**Who it affects:** Anyone who operates, maintains, or owns Boeing 727 aeroplanes in Australia.\n\n**Why it matters:** The main landing gear \"down lock\" mechanism is what keeps the wheels locked in the down position during landing. If this bolt fails, the gear could collapse on landing — a catastrophic safety risk. This directive mandates immediate action (\"forthwith\") based on a Boeing Service Bulletin (SB No. 32-106), indicating the manufacturer identified a defect requiring urgent fleet-wide correction.\n\n**Key requirements:**\n- **Applicability:** All Boeing 727 models\n- **Action:** Replace the specified bolt\n- **Compliance deadline:** Immediately (\"forthwith\")\n- **Source document:** Boeing Service Bulletin 32-106"},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The available text sets a single, specific requirement: replacement of the main landing gear down‑lock universal bolt on all Boeing 727 models and requires immediate compliance, referencing Boeing SB No. 32‑106. There is no information in the provided text indicating the scope has changed from the original intent; the directive as published appears to implement that single replacement requirement without any additional or reduced scope."},"complexity_factors":["Clear, single technical requirement (replace a specific component)","Applicability limited to a single aircraft family (Boeing 727) and stated as \"All models\"","Directive references an external service bulletin for technical detail rather than embedding complex procedures","Immediate (forthwith) compliance increases operational urgency but does not add legal complexity","Enforcement by regulator is straightforward (no layered exemptions, approvals, or phased compliance described)"],"plain_english_summary":"The directive mandates immediate replacement of the main landing‑gear down‑lock “universal bolt” on all Boeing 727 models, referencing Boeing Service Bulletin No. 32‑106 for the procedure. It affects operators, owners and maintenance organisations: compliance is compulsory, costs (parts, labour, downtime) fall to the operator, and non‑compliance can ground aircraft or prompt enforcement by CASA."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-39-main-landing-gear-down-lock-universal-bolt-replacement","history":"/api/acts/ad-b727-39-main-landing-gear-down-lock-universal-bolt-replacement/history","analysis":"/api/acts/ad-b727-39-main-landing-gear-down-lock-universal-bolt-replacement/analysis","conflicts":"/api/acts/ad-b727-39-main-landing-gear-down-lock-universal-bolt-replacement/conflicts","importantCases":"/api/acts/ad-b727-39-main-landing-gear-down-lock-universal-bolt-replacement/important-cases","documents":"/api/acts/ad-b727-39-main-landing-gear-down-lock-universal-bolt-replacement/documents"}}