{"id":"F2006B03532","name":"AD/BAe 146/84 - Rear Pressure Bulkhead Horizontal Butt Joint","slug":"ad-bae-146-84-rear-pressure-bulkhead-horizontal-butt-joint","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43099,"registerId":"commonwealth-F2006B03532-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.002.png)\n\n![](image.002.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.","sortOrder":0},{"sectionNumber":"AD/BAe 146/84 Rear Pressure Bulkhead Hor","sectionType":"part","heading":"AD/BAe 146/84 Rear Pressure Bulkhead Horizontal Butt Joint 1/2001","content":"# AD/BAe 146/84 Rear Pressure Bulkhead Horizontal Butt Joint 1/2001\n\nApplicability: All BAe 146 Series 100, 200, and 300 aircraft; Pre-Mod HCM00713A. Requirement: Inspect and modify in accordance with BAE Systems Mandatory Service Bulletin\n\n53-42.\n\nCompliance: As specified in the Requirement document for the initial and repeat inspection requirements and modification action.\n\nNote: Accomplishment of Modification HCM00713A constitutes terminating action for the repeat inspection requirement of this Directive.\n\nThis Airworthiness Directive becomes effective on 25 January 2001.\n\nBackground: The manufacturer has reviewed all structural service bulletins in order to ensure the continued airworthiness of the aircraft for life extension. This Directive requires inspections and modification action to ensure integrity of the horizontal butt joint at the rear pressure bulkhead.\n\n![Signature of David Villiers, Delegate of the Civil Aviation Safety Authority.](image.003.png)  \n\nDavid Alan Villiers\n\nDelegate of the Civil Aviation Safety Authority 7 December 2000\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 20 December 2000.","sortOrder":1}],"analysis":{"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"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD represents a focused, targeted safety intervention. It addresses a specific structural issue identified during a manufacturer's life extension review. The scope remains tightly confined to the rear pressure bulkhead horizontal butt joint on unmodified BAe 146 aircraft. There is no evidence of scope creep; the directive does exactly what its title suggests and references only the necessary technical documentation to accomplish that specific task."},"complexity_factors":["Very short document (approximately 250 words)","Only 1 defined term implicitly referenced (the modification HCM00713A)","No nested conditional logic or cross-references to other legislation","Single straightforward requirement: comply with an external technical document (Service Bulletin 53-42)","Clear applicability criteria (specific aircraft series, specific modification status)","Simple compliance structure: initial inspection, repeat inspection, terminating action"],"plain_english_summary":"This AD requires owners/operators of BAe 146 Series 100/200/300 aircraft (that have not had factory modification HCM00713A) to inspect and ultimately modify the rear pressure bulkhead horizontal butt joint per BAE Systems Mandatory Service Bulletin 53-42, with repeat inspections until the modification is installed. \n\nIt addresses a fatigue/structural risk that could cause rapid decompression or loss of control; effective 25 January 2001."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD is consistent with its stated original purpose: to ensure the integrity of the rear pressure bulkhead horizontal butt joint on BAe 146 Series 100/200/300 aircraft. It confines obligations to a specific structural location and to aircraft that are pre‑Mod HCM00713A, and it relies on the manufacturer’s service bulletin for technical detail. There is no sign in the instrument text that the scope has expanded beyond correcting that identified unsafe condition."},"complexity_factors":["Short, single‑issue directive (one part of the aircraft only)","Limited number of sections: Applicability, Requirement, Compliance, Note, Background","Dependence on one external technical document: BAE Systems Mandatory Service Bulletin 53‑42 (technical detail and intervals not reproduced in the AD)","Single terminating action referenced (Modification HCM00713A)","No nested exceptions or multiple conditional branches; clear applicability criteria (model series and pre‑mod status)"],"plain_english_summary":"**What this instrument does (mechanics)**\n\n- This is an Airworthiness Directive (AD) issued by the Civil Aviation Safety Authority (CASA) requiring inspections and a modification on certain BAe 146 aircraft.\n- It applies to all BAe 146 Series 100, 200 and 300 aircraft that have not already had Modification HCM00713A fitted (listed as “Pre‑Mod HCM00713A”) (Applicability).\n- The AD mandates that operators inspect and, where required, modify the rear pressure bulkhead horizontal butt joint following the instructions in BAE Systems Mandatory Service Bulletin 53‑42 (Requirement).\n- The timing for the initial inspection, any repeat inspections, and the modification is set out in that Service Bulletin; the AD says to comply “as specified in the Requirement document” (Compliance).\n- If an operator installs Modification HCM00713A, that installation is a terminating action — it stops the need for further repeat inspections required by this AD (Note).\n- The AD became effective on 25 January 2001 and was issued under CASA’s regulatory power (Effective date; Background; signature block).\n\n**Who this affects**\n\n- Aircraft owners and operators of BAe 146 Series 100, 200 and 300 aircraft that are still in the pre‑mod configuration (they must arrange inspections and any required modifications).\n- Maintenance organisations and repair stations that perform the inspections and modification work (they must follow the manufacturer’s Mandatory Service Bulletin).\n- CASA enforcers, who monitor compliance under the relevant CAR provision cited in the AD.\n\n**Why it matters (stated purpose and practical implications)**\n\n- Stated purpose: the manufacturer reviewed structural service information and identified the need to ensure the integrity of the horizontal butt joint at the rear pressure bulkhead (Background). The AD implements the manufacturer’s remedy to correct that unsafe condition.\n\n- Who pays: aircraft operators pay for inspections, any corrective work, parts and labour, and for aircraft downtime while work is done (Requirement; Compliance).\n\n- Who decides and enforces: CASA issued the AD under its regulatory powers and requires compliance with the manufacturer’s Service Bulletin; CASA enforcers decide compliance status and can require corrective action (signature; reference to subregulation 39.1(1) of CAR 1998 in the AD preamble).\n\n- Behaviour change required: operators must schedule and complete the inspections and modifications in accordance with the manufacturer’s Mandatory Service Bulletin. Installing Modification HCM00713A removes the need for further repeat inspections required by this AD (Note).\n\n**Costs, incentives, trade‑offs and implementation notes**\n\n- Direct costs: inspection labour, parts, modification installation, and aircraft out‑of‑service time. These are concentrated on the operators of affected aircraft (Requirement; Compliance).\n- Recurring vs one‑off burden: the AD requires repeat inspections until the terminating modification (HCM00713A) is installed. Therefore operators face either recurring inspection costs or a one‑time modification cost that eliminates repeat inspections (Note).\n- Market effects: maintenance providers stand to receive business from the inspections and modification work; operators bear the cost and possible scheduling disruption. The AD does not itself change ownership, competition rules, or contracting freedom, but it does impose mandatory maintenance obligations on affected aircraft.\n- Reliance on an external document: the AD delegates detail (timing, procedures) to BAE Systems Mandatory Service Bulletin 53‑42. That means the precise obligations, intervals and technical steps are in a manufacturer document rather than spelled out verbatim in the AD (Requirement; Compliance). This can speed issuance but requires operators to obtain and follow the Service Bulletin.\n- Implementation risks and opportunity costs: affected aircraft will need time in maintenance facilities; operators may need to re‑schedule services or short‑term fleet deployments. Availability of parts or qualified labour could affect how quickly compliance is achieved.\n\n**Concrete mechanisms to note**\n\n- The AD is narrowly targeted by aircraft model and mod status (Applicability).\n- Compliance obligations and scheduling are set by the manufacturer’s Mandatory Service Bulletin referenced in the AD (Requirement; Compliance).\n- Installing Modification HCM00713A is explicitly stated as the terminating action for repeat inspections (Note).\n\n(References in parentheses indicate the relevant AD sections: Applicability; Requirement; Compliance; Note; Background; Effective date.)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-bae-146-84-rear-pressure-bulkhead-horizontal-butt-joint","history":"/api/acts/ad-bae-146-84-rear-pressure-bulkhead-horizontal-butt-joint/history","analysis":"/api/acts/ad-bae-146-84-rear-pressure-bulkhead-horizontal-butt-joint/analysis","conflicts":"/api/acts/ad-bae-146-84-rear-pressure-bulkhead-horizontal-butt-joint/conflicts","importantCases":"/api/acts/ad-bae-146-84-rear-pressure-bulkhead-horizontal-butt-joint/important-cases","documents":"/api/acts/ad-bae-146-84-rear-pressure-bulkhead-horizontal-butt-joint/documents"}}