{"id":"F2006B02700","name":"AD/B727/176 - Horizontal Stabiliser - Elevator Hinge Support Ribs","slug":"ad-b727-176-horizontal-stabiliser-elevator-hinge-support-ribs","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42016,"registerId":"commonwealth-F2006B02700-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/176 - Horizontal Stabiliser - Elevator Hinge Support Ribs","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \n\nAIRWORTHINESS DIRECTIVE\n\n![](image.001.png)\n\n![](image.001.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\nBoeing 727 Series Aeroplanes\n\nAD/B727/176 Horizontal Stabiliser \\- Elevator Hinge\n\nSupport Ribs\n\n  \n9/2002\n\nApplicability: All Model 727 series aircraft.\n\nRequirement: Action in accordance with the technical requirements of FAA AD 2002-12-13 Amdt 39-12785.\n\nNote: Boeing Alert Service Bulletin 727-55A0091, including Appendix A refers.\n\nCompliance: As specified in the Requirement document, with a revised effective date of 5 September 2002.\n\nThis Airworthiness Directive becomes effective on 5 September 2002.\n\nBackground: The manufacturer received numerous reports of stress corrosion cracks on the elevator hinge support ribs made from 7079-T6 material. Excessive rib damage at multiple rib locations can continue to extend in size until the elevator support stiffness is decreased, and may lead to in-flight vibration and consequential damage to the elevator and horizontal stabiliser.\n\n![Signature of David Villiers, Delegate of the Civil Aviation Safety Authority.](image.002.jpeg)  \n\nDavid Alan Villiers\n\nDelegate of the Civil Aviation Safety Authority 24 July 2002\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 14 August 2002.\n\n  \nPage 1 of 1","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope: addressing a specific structural defect in a specific aircraft type. It does not expand beyond the original safety purpose of correcting stress corrosion in elevator hinge support ribs."},"complexity_factors":["Very short document (1 page)","Only 4 defined structural elements (aircraft model, specific rib part, material specification 7079-T6, referenced FAA AD)","Single straightforward requirement: comply with external FAA directive","No nested conditions or exceptions","No cross-references to other Australian legislation beyond enabling regulation (CAR 1998, subregulation 39.1(1))","Clear, fixed compliance date"],"plain_english_summary":"This Airworthiness Directive makes mandatory inspections and repairs of cracked elevator hinge support ribs on all Boeing 727s in Australia, addressing stress-corrosion damage that can cause vibration, tail damage, or loss of control. Operators must follow FAA AD 2002-12-13 and Boeing Service Bulletin 727-55A0091; the directive took effect 5 September 2002."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD maintains a focused scope: it applies to all Model 727 series aircraft and targets elevator hinge support ribs made from 7079-T6, requiring actions specified in FAA AD 2002-12-13 and Boeing Alert SB 727-55A0091. The instrument does not expand scope beyond that identified defect and references external technical documents for remedial measures (Applicability; Requirement; Note; Background)."},"complexity_factors":["Direct cross-reference to an external FAA AD (FAA AD 2002-12-13) rather than containing full technical instructions in the text (Requirement).","Reliance on a manufacturer service bulletin (Boeing Alert Service Bulletin 727-55A0091, including Appendix A) for technical detail (Note).","Fleet-wide applicability: applies to all Model 727 series aircraft, increasing aggregate inspection/repair burden on operators (Applicability).","Material- and part-specific defect: identifies stress-corrosion cracks in elevator hinge support ribs made from 7079-T6, which focuses technical remediation but may require specialised inspection/repair capability (Background).","Compliance timing and scheduling dependency: compliance is 'as specified in the Requirement document' with a revised effective date of 5 September 2002, creating reliance on external document timelines (Compliance).","Regulatory decision-making: AD issued under CASA subregulation 39.1(1) by a CASA delegate, reflecting delegated enforcement discretion (first paragraph; signature block).","Operator cost responsibility: the AD imposes inspection and corrective-action obligations on aircraft operators, implying direct operational, maintenance and repair costs (Requirement; Compliance).","Implementation risk: corrective actions and extent of repairs are defined in the external FAA/manufacturer documents, so practical complexity depends on those technical procedures rather than the AD text itself (Requirement; Note)."],"plain_english_summary":"This Airworthiness Directive requires all Boeing 727 operators to carry out the technical actions set out in FAA AD 2002-12-13 (and the referenced Boeing Alert Service Bulletin 727-55A0091) to inspect for and correct stress-corrosion cracks in elevator hinge support ribs made from 7079-T6. Compliance must follow the FAA document with an effective date of 5 September 2002.\n\nCASA’s delegate issued the AD under CAR subregulation 39.1(1); aircraft operators must perform inspections and repairs and therefore bear the operational and repair costs. The stated aim is to prevent loss of elevator support stiffness and in-flight vibration that could damage the elevator and horizontal stabiliser."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-176-horizontal-stabiliser-elevator-hinge-support-ribs","history":"/api/acts/ad-b727-176-horizontal-stabiliser-elevator-hinge-support-ribs/history","analysis":"/api/acts/ad-b727-176-horizontal-stabiliser-elevator-hinge-support-ribs/analysis","conflicts":"/api/acts/ad-b727-176-horizontal-stabiliser-elevator-hinge-support-ribs/conflicts","importantCases":"/api/acts/ad-b727-176-horizontal-stabiliser-elevator-hinge-support-ribs/important-cases","documents":"/api/acts/ad-b727-176-horizontal-stabiliser-elevator-hinge-support-ribs/documents"}}