{"id":"F2006B02645","name":"AD/B727/123 - Landing Gear Selector Valve Actuator Arm","slug":"ad-b727-123-landing-gear-selector-valve-actuator-arm","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41961,"registerId":"commonwealth-F2006B02645-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/123 - Landing Gear Selector Valve Actuator Arm","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/B727/123 Landing Gear Selector Valve Actuator Arm 11/90\n\nApplicability: Model 727 series.\n\n \n\nRequirement: Unless already accomplished, modify the selector valve actuator arm in accordance with Boeing Service Bulletin 727-32-0372, or Revision 2 of Service Bulletin\n\n727-32-0372.\n\n \n\nNote: FAA AD 90-02-08 Amdt 39-6470 refers.\n\n \n\nCompliance: Prior to 31 March 1992.\n\n \n\nBackground: This AD is issued in response to a report of an all wheels-up landing, due to a nut missing from the landing gear control selector valve actuator arm 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\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The instrument defines a single, focused obligation: modify the selector valve actuator arm on Model 727 series aeroplanes per Boeing Service Bulletin 727-32-0372 (or its Revision 2) by 31 March 1992 (Applicability; Requirement; Compliance). The text contains no indication that the scope was broadened or narrowed from a prior intent within the supplied material."},"complexity_factors":["Narrow technical scope limited to Boeing 727 series (Applicability)","Mandated reliance on an external technical document (Boeing Service Bulletin 727-32-0372 or Revision 2) rather than prescribing steps in the AD itself (Requirement)","Fixed compliance deadline creates scheduling and operational constraints (Compliance)","Limited regulatory discretion in the text — specific action and deadline prescribed (Requirement; Compliance)","Cross-reference to an FAA AD, creating inter-jurisdictional alignment dependency (Note)"],"plain_english_summary":"This airworthiness directive requires owners/operators of Boeing 727 series aeroplanes to complete the Boeing-prescribed modification to the landing gear selector valve actuator arm by 31 March 1992, issued after an all‑wheels‑up landing caused by a missing nut. It places the cost, scheduling and compliance burden on operators and relies on Boeing’s service bulletin (with FAA coordination) for the technical remedy."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive addressing a specific mechanical defect. It has not expanded beyond its original purpose of mandating a safety modification to prevent wheels-up landings."},"complexity_factors":["Single, specific mechanical component addressed (landing gear selector valve actuator arm)","Only one substantive requirement: modify per specified Boeing Service Bulletin","No defined terms section or complex interpretive provisions","Simple applicability (entire 727 series)","Single compliance deadline with no conditional exceptions","Minimal cross-referencing (only one FAA AD mentioned in a note, not incorporated by complex reference)","No nested conditions, exceptions, or discretionary powers"],"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 modifications to aircraft.\n\n**What it does:** It orders owners and operators of **Boeing 727 series aircraft** to modify the **landing gear selector valve actuator arm** — a mechanical component that helps control whether the plane's wheels extend or retract. The modification must follow specific instructions in a Boeing technical document (Service Bulletin 727-32-0372 or its Revision 2).\n\n**Why it matters:** The directive was triggered by a serious incident where a Boeing 727 landed with its wheels up because a nut was missing from this actuator arm. A \"wheels-up landing\" means the plane lands on its belly without landing gear extended — extremely dangerous and potentially catastrophic. The modification prevents this failure from happening again.\n\n**Who must comply:** Anyone operating a Boeing 727 in Australia. The work had to be completed before **31 March 1992** (this is a historical directive from November 1990).\n\n**Key point:** This is not optional maintenance — it's legally enforceable. Flying without completing this modification would violate civil aviation safety regulations."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-123-landing-gear-selector-valve-actuator-arm","history":"/api/acts/ad-b727-123-landing-gear-selector-valve-actuator-arm/history","analysis":"/api/acts/ad-b727-123-landing-gear-selector-valve-actuator-arm/analysis","conflicts":"/api/acts/ad-b727-123-landing-gear-selector-valve-actuator-arm/conflicts","importantCases":"/api/acts/ad-b727-123-landing-gear-selector-valve-actuator-arm/important-cases","documents":"/api/acts/ad-b727-123-landing-gear-selector-valve-actuator-arm/documents"}}