{"id":"F2006B03486","name":"AD/BAe 146/34 - Anti-Skid Control System","slug":"ad-bae-146-34-anti-skid-control-system","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43040,"registerId":"commonwealth-F2006B03486-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BAe 146/34 - Anti-Skid Control System","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)  British Aerospace BAe 146 Series Aeroplanes\n\n \n\nAD/BAe 146/34 Anti-Skid Control System 10/91\n\nApplicability: As specified in the Requirement Document. Requirement:  Action in accordance with BAe SB 32-124-70491A&B.\n\nNote: Compliance with this SB is classified MANDATORY by the UK CAA, and\n\nincludes mandatory modification of Anti Skid Control Boxes held as spares.\n\nCompliance: Prior to 30 June 1992.\n\n \n\nBackground:  A loss of normal braking has been reported which has been attributed to incorrect operation of the Anti Skid Control Box which may result in a single fault causing failure of the normal breaking system.\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":4,"scope_assessment":{"changed":false,"description":"The AD enforces the technical modification specified by the BAe Service Bulletin and requires modification of spares by a set deadline. There is no indication in the AD text that the scope was broadened or narrowed from its original safety-remediation intent: it mandates the manufacturer’s bulletin remedial actions for affected aircraft and spare Anti Skid Control Boxes and sets a compliance date. Any further scope detail (such as precise serial-number applicability or exemptions) is delegated to the referenced Requirement Document and Service Bulletin rather than altered by this AD."},"complexity_factors":["Reference to external technical documents (BAe Service Bulletin 32-124-70491A&B) for the required work rather than detailing the remedy in the AD itself (Requirement).","Applicability is given only as “As specified in the Requirement Document,” requiring operators to consult another document to know if a particular aircraft is affected (Applicability).","Mandatory modification of spare parts (Anti Skid Control Boxes) increases logistical complexity for operators’ inventory and maintenance planning (Note).","Fixed, relatively near-term deadline for compliance creates concentrated scheduling pressure on maintenance resources (Compliance).","Safety-critical hardware change that may require certified maintainers, parts procurement, and verification steps not specified in the AD text (Background; Requirement).","Cross-jurisdictional reference to UK CAA classification increases regulatory interdependence (Note)."],"plain_english_summary":"What this instrument does (mechanics)\n\n- It requires operators of British Aerospace BAe 146 series aeroplanes to carry out the work set out in BAe Service Bulletin 32-124-70491A & B on the aeroplane anti-skid control system. (Requirement)\n- It explicitly includes mandatory modification of Anti Skid Control Boxes held as spares. (Note)\n- It sets a compliance deadline: the required work must be completed prior to 30 June 1992. (Compliance)\n- Applicability is stated as \"As specified in the Requirement Document,\" so the precise fleet subset and serial-number detail are given in that referenced document rather than in this AD. (Applicability)\n\nWhy the change was made (official rationale)\n\n- The AD cites reports of a loss of normal braking attributed to incorrect operation of the Anti Skid Control Box, where a single fault could cause failure of the normal braking system. This safety observation is the stated reason for mandating the modification. (Background)\n- The AD records that compliance with the BAe Service Bulletin is classified as MANDATORY by the UK Civil Aviation Authority. The AD therefore directs action in accordance with that Service Bulletin. (Note)\n\nWho pays, who decides, and what behaviour changes\n\n- Who pays: Aircraft operators (or their maintenance providers) are responsible for performing the modification and for modifying spare control boxes. The AD does not allocate funding or provide reimbursement. (Requirement; Note)\n- Who decides: The regulator issues the Airworthiness Directive and makes compliance mandatory by reference to the BAe Service Bulletin and the UK CAA classification. The AD defers technical detail to the manufacturer’s Service Bulletin. (Requirement; Note)\n- Behavioural change required: Operators must schedule and carry out the Service Bulletin actions on affected aircraft and on spare Anti Skid Control Boxes before the deadline. This will change maintenance planning, parts inventory management, and aircraft availability until work is complete. (Requirement; Note; Compliance)\n\nCosts, incentives, trade-offs, and implementation considerations\n\n- Compliance burden: The AD mandates hardware modification to a safety-critical system. That typically requires parts, skilled maintenance labour, and aircraft downtime; those costs are borne by operators or their maintenance contractors. The AD text itself specifies the modification but not the cost or funding mechanism. (Requirement; Note)\n- Dependence on external document: The technical work is specified in the BAe Service Bulletin, which the AD requires operators to follow. Because the AD references an external Requirement Document for applicability and an external Service Bulletin for the remedy, the regulator delegates technical specifics to those documents. That creates a dependency on manufacturer and foreign-regulator materials to determine precise scope and technical steps. (Applicability; Requirement; Note)\n- Deadline and operational impact: The fixed compliance date creates a schedule pressure that can concentrate maintenance activity ahead of the deadline, potentially affecting aircraft availability and maintenance capacity. The AD does not provide phased compliance or exemptions in its text. (Compliance)\n- Risk and testing: The AD responds to a reported single-fault vulnerability in the Anti Skid Control Box. The required modification is intended to eliminate or mitigate that single-fault failure mode; the AD does not itself describe test or verification procedures beyond directing compliance with the Service Bulletin. (Background; Requirement)\n\nMarket and enterprise effects (what can be observed from the text)\n\n- Maintenance markets: The requirement for a specific modification creates demand for parts and qualified maintenance work, which benefits organisations that supply or perform the modification. The AD does not direct which contractors must perform the work. (Requirement; Note)\n- Spare parts management: The AD requires modification of spare Anti Skid Control Boxes, so operators must either modify existing spares or replace them with modified units before the deadline. That affects inventory decisions and the timing of spare usage. (Note; Compliance)\n- Competition and contract freedom: The AD prescribes a technical outcome (the Service Bulletin modification) but does not prescribe which certified maintainer must carry out the work. Operators retain contractual freedom to choose compliant maintenance providers subject to regulatory approvals and certification requirements that are standard in aviation. (Requirement)\n\nLimitations of what the AD states\n\n- The AD does not include a cost estimate, funding mechanism, exemption process, or detailed applicability list in its text; those items are in the referenced Requirement Document and Service Bulletin. (Applicability; Requirement)\n- The AD records the safety incident and mandates remediation but does not itself provide test data, failure-rate estimates, or risk-quantified analysis. (Background)\n\nKey citations\n\n- Applicability: “As specified in the Requirement Document.” (Applicability)\n- Requirement: “Action in accordance with BAe SB 32-124-70491A&B.” (Requirement)\n- Note: “Compliance with this SB is classified MANDATORY by the UK CAA, and includes mandatory modification of Anti Skid Control Boxes held as spares.” (Note)\n- Compliance: “Prior to 30 June 1992.” (Compliance)\n- Background: description of reported loss of normal braking and attribution to the Anti Skid Control Box. (Background)"},"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 an anti-skid system modification."},"complexity_factors":["Extremely short document (under 200 words)","Only one substantive requirement: comply with referenced Service Bulletin","No defined terms section — relies entirely on external technical document (BAe SB 32-124-70491A&B)","No conditional logic, exceptions, or nested provisions","Single applicability trigger ('As specified in the Requirement Document')","Straightforward compliance deadline with no alternative methods or phased implementation"],"plain_english_summary":"This is an **Airworthiness Directive** (a mandatory safety order) issued by Australia's Civil Aviation Safety Authority for **British Aerospace BAe 146 series aircraft**.\n\n**What it does:**\n- Requires aircraft operators to follow a specific British Aerospace Service Bulletin (SB 32-124-70491A&B) to fix a dangerous fault in the **anti-skid braking system**.\n- The problem: A single electrical fault in the Anti-Skid Control Box could cause **complete failure of normal brakes** — a serious safety risk during landing.\n- The fix involves modifying or replacing the control boxes, including any spare units held in inventory.\n\n**Who it affects:**\n- Airlines and operators flying BAe 146 aircraft in Australia.\n- Maintenance crews responsible for brake system repairs.\n\n**Why it matters:**\n- Brake failure on landing can lead to runway overruns, collisions, or crashes.\n- The UK aviation regulator (CAA) classified this fix as **mandatory**, and Australia followed suit to maintain safety standards.\n- Operators had a hard deadline: **before 30 June 1992**.\n\n**Key takeaway:** This directive forces airlines to fix a potentially deadly brake defect by a specific deadline to keep their aircraft airworthy."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bae-146-34-anti-skid-control-system","history":"/api/acts/ad-bae-146-34-anti-skid-control-system/history","analysis":"/api/acts/ad-bae-146-34-anti-skid-control-system/analysis","conflicts":"/api/acts/ad-bae-146-34-anti-skid-control-system/conflicts","importantCases":"/api/acts/ad-bae-146-34-anti-skid-control-system/important-cases","documents":"/api/acts/ad-bae-146-34-anti-skid-control-system/documents"}}