{"id":"F2006B02788","name":"AD/B727/84 Amdt 3 - Main Landing Gear Lock System","slug":"ad-b727-84-amdt-3-main-landing-gear-lock-system","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42130,"registerId":"commonwealth-F2006B02788-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/84 Amdt 3 - Main Landing Gear Lock System","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/B727/84\n\nAmdt 3\n\n\nMain Landing Gear Lock System 9/88\n\n \n\nApplicability: All models to line number 1125.\n\n \n\nRequirement: Action in accordance with Boeing S.B. 727-32-0237 Rev 4.\n\n \n\nNote: FAA AD 79-04-01 R3 is referenced for earlier issues of this Directive.\n\n \n\nCompliance: Prior to 31 December 1988.\n\n \n\nBackground: Aircraft were initially modified to provide higher strength components in the MLG lock system. Since that time there have been reports of missing nuts and the loss of a bolt.\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 Amendment 3 to an existing directive. The scope remains tightly focused on the original safety issue (main landing gear lock system integrity) and does not expand beyond the specific Boeing 727 models originally covered. The amendment appears to update the reference to the latest Boeing service bulletin revision without broadening the directive's application."},"complexity_factors":["Very short document (under 200 words)","Only 4 operative provisions: applicability, requirement, note, and compliance","Single cross-reference to a Boeing Service Bulletin and a prior FAA directive","No defined terms section","No conditional logic or nested exceptions","Straightforward command structure: 'do X by Y date'"],"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) that requires specific repairs or inspections on aircraft.\n\n**What it does:** It orders owners and operators of **Boeing 727 series aeroplanes** (up to production line number 1125) to carry out specific maintenance work on the **main landing gear lock system** — the mechanism that keeps the plane's main wheels locked in place when extended for landing.\n\n**Why it matters:** The landing gear lock system is critical for safe landings. This directive was issued because there had been reports of **missing nuts and a lost bolt** in this system, which could cause the landing gear to collapse or fail to lock properly. The required fix follows **Boeing Service Bulletin 727-32-0237 Revision 4** (a manufacturer's technical instruction for repairs).\n\n**Who must comply:** Anyone operating affected Boeing 727 aircraft in Australia had to complete this work **before 31 December 1988**.\n\n**Key point:** This is a **time-critical safety mandate** — not optional guidance. Non-compliance would mean the aircraft cannot legally fly."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This instrument is presented as Amendment 3 and specifies compliance with a particular revision of the Boeing service bulletin (Boeing S.B. 727-32-0237 Rev 4), while also referencing FAA AD 79-04-01 R3 for earlier issues. That combination indicates the directive has been updated from earlier iterations to require the work described in the cited, newer service‑bulletin revision rather than an earlier revision. (Requirement; Note)"},"complexity_factors":["References an external manufacturer Service Bulletin (Boeing S.B. 727-32-0237 Rev 4) for technical steps rather than setting out details in the AD itself (Requirement).","Applicability limited to aircraft up to a production line number, requiring operators to check aircraft serial/line records to determine applicability (Applicability).","Hard compliance deadline (prior to 31 December 1988) imposes scheduling constraints and potential operational downtime (Compliance).","Cross‑reference to an earlier FAA AD for prior issues requires operators to track related historical directives to ensure full compliance (Note).","Safety‑critical hardware work (MLG lock system) may require specialised parts and skilled maintenance resources, creating logistical and supply risks (Background).","The AD does not state alternative compliance procedures or exemptions in the supplied text, so procedural discretion lies with the manufacturer’s SB and the regulator’s enforcement practice (Requirement; Compliance)."],"plain_english_summary":"This Airworthiness Directive mandates that owners/operators of Boeing 727s (line numbers up to 1125) complete the work in Boeing Service Bulletin 727‑32‑0237 Rev 4 on the main landing gear lock system by 31 December 1988, after reports of missing nuts and a lost bolt. It affects operators and maintenance providers, imposes compliance costs on aircraft owners, and is enforced by the Civil Aviation Safety Authority with technical content supplied by Boeing."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-84-amdt-3-main-landing-gear-lock-system","history":"/api/acts/ad-b727-84-amdt-3-main-landing-gear-lock-system/history","analysis":"/api/acts/ad-b727-84-amdt-3-main-landing-gear-lock-system/analysis","conflicts":"/api/acts/ad-b727-84-amdt-3-main-landing-gear-lock-system/conflicts","importantCases":"/api/acts/ad-b727-84-amdt-3-main-landing-gear-lock-system/important-cases","documents":"/api/acts/ad-b727-84-amdt-3-main-landing-gear-lock-system/documents"}}