{"id":"F2006B02626","name":"AD/B727/103 - MLG Side Strut Downlock Bearing and Bolt","slug":"ad-b727-103-mlg-side-strut-downlock-bearing-and-bolt","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41942,"registerId":"commonwealth-F2006B02626-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/103 - MLG Side Strut Downlock Bearing and Bolt","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/B727/103 MLG Side Strut Downlock Bearing and Bolt 9/87\n\nApplicability: All models.\n\n \n\nRequirement: Action in accordance with Boeing Service Bulletin 727-32-0341, dated 18 December 1986, or later Revision.\n\n \n\nNote: FAA AD 87-06-10 Amendment 39-5578 refers.\n\n \n\nCompliance: Prior to accumulating 10,000 landings, OR Prior to accumulating 6 years total time in service of affected bearings, OR Prior to 13 April 1988.\n\n \n\nBackground: Reports have been received of deterioration of the MLG side strut downlock bearing by corrosion which, if not corrected, can prevent the proper extension of the landing gear. These reports prompted the Federal Aviation Agency to issue an Airworthiness Directive.\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, targeted safety directive addressing a specific mechanical defect in a specific aircraft type. It has not expanded beyond its original purpose of mandating inspection/replacement of corroded landing gear bearings."},"complexity_factors":["Very short document (approximately 200 words)","Only 3 defined elements: applicability (all Boeing 727 models), specific Boeing Service Bulletin reference, and three alternative compliance deadlines","No cross-references to other legislation beyond a note about the related FAA directive","Single, straightforward requirement with clear alternative compliance paths","No nested exceptions or conditional logic — the 'OR' structure is simple and inclusive"],"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 and operators of **Boeing 727 aircraft** to inspect and fix a specific mechanical problem with the **main landing gear (MLG)**. The issue involves the \"side strut downlock bearing and bolt\" — a critical component that helps lock the landing gear in place when extended.\n\n**The problem:**\nThe bearing can corrode (rust/deteriorate). If this isn't caught and fixed, the landing gear might not extend properly when the pilot tries to lower it — a serious safety risk.\n\n**Who must act:**\nAnyone operating a Boeing 727 of any model in Australia.\n\n**What they must do:**\nFollow the instructions in a specific Boeing technical document (Service Bulletin 727-32-0341 from December 1986, or any later updated version). This typically involves inspecting the bearing for corrosion and replacing it if necessary.\n\n**When they must do it:**\nBy the **earliest** of these three deadlines:\n- Before the aircraft completes 10,000 landings, **OR**\n- Before the bearing has been in service for 6 years total, **OR**\n- Before 13 April 1988 (this was the hard deadline when the AD was issued in 1987).\n\n**Why it matters:**\nThis prevents potential landing gear failures. The directive was triggered after reports of corrosion and a similar safety order from the US Federal Aviation Administration (FAA)."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive's scope aligns with its stated purpose: addressing corrosion of the MLG side-strut downlock bearing and bolt on Boeing 727s by requiring service-bulletin actions for all models. The text shows no expansion beyond that original safety objective; compliance mechanics (service-bulletin reference and the three compliance triggers) define how the scope is implemented rather than broadening it."},"complexity_factors":["Applicability is broad: \"All models\" of Boeing 727 are covered, increasing the universe of affected operators (Applicability).","Mandates action \"in accordance with\" a manufacturer service bulletin, creating dependency on an external document and its later revisions (Requirement: Boeing Service Bulletin 727-32-0341).","Multiple alternative compliance triggers (10,000 landings OR 6 years in service OR fixed calendar date) require operators to track usage and part age precisely (Compliance).","Safety-critical subject matter (landing-gear extension) raises enforcement and documentation demands for maintainers and operators (Background).","Reference to FAA AD introduces harmonisation and potential cross-jurisdictional expectations but also reliance on foreign authority for technical direction (Note: FAA AD 87-06-10)."],"plain_english_summary":"This Airworthiness Directive requires operators of Boeing 727 aeroplanes to inspect and take the actions set out in Boeing Service Bulletin 727-32-0341 (or later revision) for the main landing gear (MLG) side-strut downlock bearing and bolt. It applies to all models and must be done before an affected bearing reaches 10,000 landings, six years in service, or by 13 April 1988. The measure aims to address corrosion that could prevent proper gear extension; operators bear the cost and compliance responsibility."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-103-mlg-side-strut-downlock-bearing-and-bolt","history":"/api/acts/ad-b727-103-mlg-side-strut-downlock-bearing-and-bolt/history","analysis":"/api/acts/ad-b727-103-mlg-side-strut-downlock-bearing-and-bolt/analysis","conflicts":"/api/acts/ad-b727-103-mlg-side-strut-downlock-bearing-and-bolt/conflicts","importantCases":"/api/acts/ad-b727-103-mlg-side-strut-downlock-bearing-and-bolt/important-cases","documents":"/api/acts/ad-b727-103-mlg-side-strut-downlock-bearing-and-bolt/documents"}}