{"id":"F2006B03473","name":"AD/BAe 146/20 - Avionics Rack Earth Stud","slug":"ad-bae-146-20-avionics-rack-earth-stud","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43027,"registerId":"commonwealth-F2006B03473-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BAe 146/20 - Avionics Rack Earth Stud","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 146/20 Avionics Rack Earth Stud 9/90\n\nApplicability: All BAe 146 series aeroplanes as detailed in the Requirement Document. Requirement:               Action in accordance with BAe 146 Service Bulletin 24-60.\n\nNote: Compliance with this Service Bulletin has been classified mandatory by the UK CAA.\n\n \n\nCompliance: Prior to 6 November 1990.\n\n \n\nBackground: BAe have advised that one operator has experienced chafing of an electrical loom on this earth stud.\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":2,"scope_assessment":{"changed":false,"description":"The AD’s scope is stated explicitly: it applies to all BAe 146 series aeroplanes as identified in the Requirement Document and mandates compliance with BAe Service Bulletin 24-60 prior to 6 November 1990. The text does not indicate any change from an earlier or different scope within the document itself; no narrowing or expansion of affected aircraft or actions is set out beyond those statements. (Applicability, Requirement, Compliance)"},"complexity_factors":["Narrow technical scope limited to the avionics rack earth stud and related loom (Background).","Clear, single prescriptive action: follow BAe Service Bulletin 24-60 (Requirement).","Fixed calendar compliance deadline simplifies scheduling but creates time pressure (Compliance).","Dependence on an external document (BAe Service Bulletin 24-60) for technical detail increases operational steps (Requirement).","Cross-reference to a Requirement Document for applicability creates a minor administrative lookup burden (Applicability).","Reference to UK CAA classification adds a cross-jurisdictional regulatory element but does not add procedural complexity to the AD itself (Requirement / Note)."],"plain_english_summary":"What this instrument does (mechanically)\n\n- It requires operators of BAe 146 series aeroplanes to carry out the work specified in British Aerospace (BAe) Service Bulletin 24-60 in relation to the avionics rack earth stud. (Requirement)\n- The directive applies to all BAe 146 series aeroplanes as identified in the Requirement Document. (Applicability)\n- The work must be completed before 6 November 1990. (Compliance)\n\nWho it affects\n\n- Aircraft operators that own or run BAe 146 series aeroplanes referenced in the Requirement Document are required to comply. (Applicability)\n- Maintenance organisations performing the work will be engaged by those operators. (Requirement)\n\nWhy it matters (official rationale and practical implications)\n\n- The stated reason is that BAe reported one operator experienced chafing of an electrical loom on this earth stud. (Background)\n- The UK Civil Aviation Authority has classified compliance with the BAe Service Bulletin as mandatory; the AD directs operators to follow that Service Bulletin. (Requirement / Note)\n\nPractical mechanics, incentives and costs\n\n- Who pays: aircraft operators must fund and schedule the inspection/repair/modification work set out in BAe Service Bulletin 24-60. (Requirement)\n- Who decides what to do: the Service Bulletin specifies the actions; the AD makes following that Service Bulletin mandatory for the affected aeroplanes. The Requirement Document identifies which individual aeroplanes are covered. (Requirement, Applicability)\n- Behaviour change required: operators must arrange the specified maintenance on the avionics rack earth stud and associated loom before the stated deadline. (Requirement, Compliance)\n- Compliance burden: operators will need to allocate maintenance labour, parts (if any are required by the Service Bulletin), and aircraft downtime prior to the compliance date. The AD itself does not list technical steps or parts — those are in the Service Bulletin — so operators must obtain and follow that external document. (Requirement)\n\nTrade-offs, implementation risks and discretion\n\n- The AD imposes a fixed deadline for compliance (prior to 6 November 1990), which creates a short-term scheduling and cost obligation for operators. (Compliance)\n- The AD does not provide technical detail; it delegates technical specification and precise required work to BAe Service Bulletin 24-60. That delegation concentrates technical discretion in the service bulletin author (BAe) while leaving enforcement and the compliance requirement to the regulator via this AD. (Requirement)\n- The AD records a single reported chafing event as the immediate background for the requirement; it does not quantify prevalence or risk beyond that statement. (Background)\n\nConcrete, source-cited points\n\n- Applicability: covers “All BAe 146 series aeroplanes as detailed in the Requirement Document.” (Applicability)\n- Required action: “Action in accordance with BAe 146 Service Bulletin 24-60.” (Requirement)\n- Deadline: “Prior to 6 November 1990.” (Compliance)\n- Rationale: BAe advised of one operator’s experience of chafing of an electrical loom on this earth stud. (Background)\n- Regulatory context: the Service Bulletin has been classified mandatory by the UK CAA; the AD references that classification. (Requirement / Note)\n\nWhat this does not say (limits of the document)\n\n- The AD does not include the technical steps, parts, labour hours, or cost estimates — those are in BAe Service Bulletin 24-60. (Requirement)\n- The AD does not expand or narrow the group of affected aeroplanes beyond what is identified in the Requirement Document; it does not state ongoing monitoring obligations after the one-off compliance. (Applicability, Compliance)\n\nOverall takeaway\n\nOperators of BAe 146 aeroplanes listed in the Requirement Document must complete the maintenance/modification actions set out in BAe Service Bulletin 24-60 on the avionics rack earth stud before 6 November 1990. The AD delegates the technical specification to BAe’s Service Bulletin, and relies on a UK CAA determination to make that Service Bulletin mandatory. (Applicability, Requirement, Compliance, Background, Note)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive addressing a specific technical defect. It has not expanded beyond its original purpose of mandating a single wiring inspection/modification."},"complexity_factors":["Very short document (under 200 words)","Only one substantive requirement: comply with an external technical document (Service Bulletin 24-60)","No defined terms section","No conditional logic or nested exceptions","Single applicability criterion (all BAe 146 series aircraft)","Single compliance deadline with no alternatives or phased approach"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:**\nOrders owners and operators of **British Aerospace BAe 146 series aircraft** to carry out a specific safety fix on the electrical system. The fix involves inspecting and modifying an \"earth stud\" (a grounding point for electrical wiring) in the avionics rack (the compartment housing the aircraft's electronic equipment).\n\n**Why it matters:**\nOne airline had already experienced **chafing** (wear and tear causing damage to insulation) on electrical wiring where it rubbed against this earth stud. Damaged wiring can cause electrical failures, sparks, or even fire — serious risks in an aircraft.\n\n**Who must comply:**\nAnyone operating a BAe 146 aircraft in Australia. They must follow the technical instructions in **BAe Service Bulletin 24-60** (the manufacturer's official repair notice).\n\n**Deadline:**\nThe work had to be completed before **6 November 1990**.\n\n**Key point:**\nThis wasn't optional. The UK aviation regulator had already made this fix mandatory, and Australia followed suit to ensure the same safety standard applied here."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bae-146-20-avionics-rack-earth-stud","history":"/api/acts/ad-bae-146-20-avionics-rack-earth-stud/history","analysis":"/api/acts/ad-bae-146-20-avionics-rack-earth-stud/analysis","conflicts":"/api/acts/ad-bae-146-20-avionics-rack-earth-stud/conflicts","importantCases":"/api/acts/ad-bae-146-20-avionics-rack-earth-stud/important-cases","documents":"/api/acts/ad-bae-146-20-avionics-rack-earth-stud/documents"}}