{"id":"F2006B03459","name":"AD/BAe 146/106 - Elevator 'G' Weight Support Structure","slug":"ad-bae-146-106-elevator-g-weight-support-structure","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43013,"registerId":"commonwealth-F2006B03459-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.001.png)\n\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 CASR 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\n![](image.001.png)  \n\nBritish Aerospace BAe 146 Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/BAe 146/106 Elevator 'G' Weight Suppo","sectionType":"part","heading":"AD/BAe 146/106 Elevator 'G' Weight Support Structure 8/2003","content":"# AD/BAe 146/106 Elevator 'G' Weight Support Structure 8/2003\n\nApplicability: All BAe 146 aircraft, pre Modification HCM00654A.\n\nRequirement: Inspect in accordance with BAE Systems Mandatory Service Bulletin ISB. 27-037 Revision 3.\n\nCompliance: As specified in the Requirement document.\n\nThis Airworthiness Directive becomes effective on 7 August 2003.\n\nBackground: To ensure the continued airworthiness of the BAe 146 aircraft for life extension, it has been necessary to review all structural service bulletins. As a result of this review, the Requirement document has been revised to mandatory status as agreed by the Structural Task Group. Cracks have been reported in the elevator ‘G’ weight support structure on aircraft in service. If corrective action is not taken, complete failure of the support structure may occur which could adversely affect elevator control.\n\n![Signature of David Villiers, Delegate of the Civil Aviation Safety Authority.](image.002.jpeg)  \n\nDavid Villiers\n\nDelegate of the Civil Aviation Safety Authority 18 June 2003\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 16 July 2003.","sortOrder":1}],"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 on a specific aircraft type. It has not expanded beyond its original safety purpose."},"complexity_factors":["Very short document (under 300 words)","Only 1 defined term implicitly referenced (Modification HCM00654A)","Single, clear requirement with no nested conditions or exceptions","No cross-references to other legislation beyond the enabling regulation (CASR 1998 subreg 39.1(1))","Straightforward applicability test (all aircraft pre-specific modification)","Compliance delegated entirely to external technical document (the Service Bulletin)"],"plain_english_summary":"This mandatory Airworthiness Directive orders operators of BAe 146 aircraft without Modification HCM00654A to inspect the elevator \"G\" weight support structure per BAE Systems Mandatory Service Bulletin ISB.27‑037 Rev 3. Cracks have been found in service that, if unchecked, could lead to loss of elevator control, so the previously recommended bulletin is now compulsory to prevent potential catastrophic flight-control failure."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"This AD converted an existing structural Service Bulletin into a mandatory regulatory requirement. Originally the Service Bulletin appears to have been advisory guidance; the AD makes compliance compulsory for all BAe 146 aircraft that have not received Modification HCM00654A. That change increases the legal force of the Service Bulletin, broadens enforcement (adds a legal sanction for non‑compliance), and thereby shifts costs from voluntary operator discretion to a regulated compliance obligation (see Background; Requirement; Applicability)."},"complexity_factors":["Short document focused on a single technical issue (elevator 'G' weight support structure)","Single applicability condition (all BAe 146 aircraft pre Modification HCM00654A)","One compulsory external reference: BAE Systems Mandatory Service Bulletin ISB.27-037 Revision 3","Compliance timing delegated entirely to the Service Bulletin (no complex timing rules in the AD itself)","One regulatory provenance cross‑reference: CASR subregulation 39.1(1)"],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- This is an Airworthiness Directive (AD) that requires inspections of a specific part of British Aerospace BAe 146 aeroplanes.\n- It applies to all BAe 146 aircraft that have not had Modification HCM00654A installed (Applicability).\n- The AD requires operators to carry out the inspection exactly as described in BAE Systems Mandatory Service Bulletin ISB.27-037 Revision 3 (Requirement).\n- The timing and intervals for those inspections are whatever the Service Bulletin specifies (Compliance).\n- The AD took effect on 7 August 2003 (Effective date).\n\n**Who it affects**\n\n- Aircraft operators and owners of BAe 146 aeroplanes that are still in the pre‑Modification HCM00654A configuration.\n- Maintenance organisations and licensed engineers who will perform the inspections and any repairs required by the Service Bulletin.\n- The aircraft manufacturer and parts suppliers to the extent inspections reveal defects that must be fixed.\n\n**Why it matters (stated purpose and technical risk)**\n\n- The background states that cracks have been reported in the elevator 'G' weight support structure on in‑service aircraft (Background).\n- If not corrected, the support structure could fail and that could adversely affect elevator control — i.e. a safety risk to flight control (Background).\n- To address that unsafe condition the Service Bulletin was elevated to mandatory status and this AD enforces it.\n\n**Who pays, who decides, and what changes in behaviour**\n\n- Operators pay: costs include inspection labour, aircraft downtime, and any repairs or parts required if cracks are found.\n- The Civil Aviation Safety Authority (CASA), via its delegate under CASR subregulation 39.1(1), makes compliance legally mandatory; the technical content of the required work comes from the BAE Systems Service Bulletin (Requirement; CASR reference in preamble).\n- Practical behaviour changes: operators must schedule and record inspections per ISB.27-037 Rev 3; if operators want to avoid recurring inspections they can install Modification HCM00654A (the AD only applies to aircraft pre‑modification), which changes the aircraft status and removes that applicability.\n\n**Costs, incentives and trade‑offs**\n\n- Direct costs: inspections and repairs increase maintenance expenditure and aircraft downtime for affected operators.\n- Incentive to modify: making the Service Bulletin mandatory increases the economic attractiveness of installing Modification HCM00654A to remove the inspection obligation for future operations (the AD targets aircraft pre‑HCM00654A).\n- Concentrated benefits: maintenance providers and parts suppliers may gain identifiable business from required inspections and fixes; costs are distributed among the set of affected operators.\n- Implementation risks: effective mitigation depends on accurate inspection practice and timely repairs. Any ambiguity in applying the Service Bulletin could cause inconsistent outcomes; the AD delegates technical detail to the Service Bulletin, so clear instructions there are essential.\n\n**Mechanics of enforcement and compliance**\n\n- Compliance is legally required by the AD; operators must follow the inspection schedule and repair instructions contained in ISB.27-037 Rev 3 (Requirement/Compliance).\n- The AD was issued by CASA's delegate under subregulation 39.1(1) of CASR 1998 (preamble).\n\n**Source claims vs. concrete effects**\n\n- The AD states its purpose as ensuring continued airworthiness and addressing reported cracks (Background). That stated purpose is implemented by converting the Service Bulletin into a mandatory inspection requirement; the concrete effect is a regulatory obligation on operators until the aircraft has Modification HCM00654A.\n\n(Sections cited: Applicability; Requirement; Compliance; Background.)"},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-bae-146-106-elevator-g-weight-support-structure","history":"/api/acts/ad-bae-146-106-elevator-g-weight-support-structure/history","analysis":"/api/acts/ad-bae-146-106-elevator-g-weight-support-structure/analysis","conflicts":"/api/acts/ad-bae-146-106-elevator-g-weight-support-structure/conflicts","importantCases":"/api/acts/ad-bae-146-106-elevator-g-weight-support-structure/important-cases","documents":"/api/acts/ad-bae-146-106-elevator-g-weight-support-structure/documents"}}