{"id":"F2006B06538","name":"AD/RAD/83 - Honeywell MST 67A Transponder","slug":"ad-rad-83-honeywell-mst-67a-transponder","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":48215,"registerId":"commonwealth-F2006B06538-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# ![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\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\nRadio Communication and Navigation Equipment","sortOrder":0},{"sectionNumber":"AD/RAD/83 Honeywell MST 67A Transponder ","sectionType":"part","heading":"AD/RAD/83 Honeywell MST 67A Transponder 10/2004","content":"# AD/RAD/83 Honeywell MST 67A Transponder 10/2004\n\nApplicability: Honeywell International (formerly AlliedSignal; Bendix King) MST 67A Mode S transponders with the following part number/serial number ranges:","sortOrder":1},{"sectionNumber":"Part Number","sectionType":"part","heading":null,"content":"## Part Number\n\n066-01143-1101, \\-1202 and \\-1301\n\n066-01143-1602","sortOrder":2},{"sectionNumber":"Serial Number Range","sectionType":"part","heading":"Serial Number Range","content":"##   \nSerial Number Range\n\nAll serial numbers up to and including 1141\n\nAll serial numbers up to and including 1503","sortOrder":3},{"sectionNumber":"Radio Communication and Navigation Equip","sectionType":"part","heading":"Radio Communication and Navigation Equipment","content":"## Radio Communication and Navigation Equipment\n\nAD/RAD/83 (continued)\n\nBackground: The European Transponder Monitoring and Testing Facility identified the Honeywell MST 67A transponder as not responding correctly to Mode S ‘all call’ (UF 11) interrogations. This could result in aircraft not being detected by air traffic control in a Modes S radar environment.\n\n![Signature of Gary J Carr Delegate of the Civil Aviation Safety Authority](image.002.jpeg)  \n\nGary J Carr\n\nDelegate of the Civil Aviation Safety Authority 16 August 2004\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 8 September 2004.","sortOrder":4}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD remains tightly scoped to its original purpose: addressing a specific technical defect in identified Honeywell transponder models. The applicability section precisely limits coverage by part and serial number, showing no scope creep from the original safety concern identified by European testing facilities."},"complexity_factors":["Short, single-purpose directive (approximately 1 page)","Limited applicability: only 4 specific part numbers with defined serial number cut-offs","No nested exceptions or conditional logic — applies straightforwardly to identified equipment","Minimal cross-referencing: cites only CASR 1998 subregulation 39.1(1) as enabling power","Clear structure: Applicability, Background, Requirement, Compliance sections follow standard AD format","Technical terminology limited to specific equipment identifiers (part numbers, serial ranges)"],"plain_english_summary":"This CASA Airworthiness Directive mandates inspection or modification of certain Honeywell MST 67A Mode S transponders that can fail to respond to “all call” radar signals. It affects operators of aircraft fitted with specified part and serial-numbered units and is intended to prevent loss of radar identification that could compromise air traffic safety."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD, as presented, remains narrowly focused on correcting a specific transponder failure mode (non-response to Mode S 'all call' UF 11 interrogations) for a defined set of part numbers and serial ranges. There is no indication in the text provided that the scope has expanded beyond that original safety-purpose (identifying the unsafe condition and mandating corrective action for the affected units)."},"complexity_factors":["Short document focused on a single unsafe condition (Mode S 'all call' UF 11 non-response).","Clear applicability by part numbers and limited serial-number ranges (two part-number groups, two serial-number limits).","Minimal cross-references (single citation to CASR subregulation 39.1(1)).","Requirement and compliance detail are referenced but not included in the excerpt, creating an information gap but not intrinsic legal complexity.","No nested exceptions, few defined terms, and no conditional logic in the provided text."],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- This is an Airworthiness Directive (AD) issued by the Civil Aviation Safety Authority (CASA) that targets specific Honeywell MST 67A Mode S transponders.  It identifies an unsafe condition and requires operators to carry out the corrective action(s) set out in the AD's requirement section (the detailed instructions themselves are not included in the excerpt provided).\n\n**Which equipment is covered**\n\n- The AD applies to Honeywell MST 67A Mode S transponders with these part numbers and serial-number ranges:\n  - Part numbers 066-01143-1101, -1202 and -1301 — all serial numbers up to and including 1141\n  - Part number 066-01143-1602 — all serial numbers up to and including 1503\n\n**Why CASA issued it (stated reason)**\n\n- The European Transponder Monitoring and Testing Facility found that these transponders may not respond correctly to Mode S “all call” (UF 11) interrogations.  CASA states that this defect could cause affected aircraft not to be detected by air traffic control in a Mode S radar environment.  The AD therefore directs specific corrective actions to address that unsafe condition.\n\n**Who is affected and who decides**\n\n- Aircraft operators and owners whose aircraft are fitted with the listed MST 67A transponders are affected.  Maintenance organisations and avionics repair stations that service these transponders will also be involved.  CASA (through its designated delegate) is the decision-maker issuing the AD and setting the compliance requirements.\n\n**What behaviour changes and obligations result**\n\n- Operators must follow the AD’s requirement section: that typically means inspecting, modifying, repairing or replacing the transponder(s) in accordance with the AD and within any compliance time stated there.  The owner/operator bears the cost and scheduling burden of compliance, including aircraft downtime and maintenance labour.\n\n**Costs, incentives and trade-offs (practical implications)**\n\n- Who pays: aircraft owners/operators pay for inspections, repairs or replacements and for any downtime while the aircraft is grounded or out of service.\n- Service providers: Honeywell, authorised service centres and independent avionics shops stand to receive work for parts, software updates, or repairs.\n- Safety benefit is broadly distributed to airspace users and air traffic services; the direct cost is concentrated on individual owners/operators of affected aircraft.\n- Implementation risk and compliance burden: depending on the AD’s detailed requirement and compliance timeframe, smaller operators or older aircraft may face disproportionate operational and financial impacts.  If the AD requires replacement rather than a field fix, parts availability and lead times become practical constraints.\n- Market effects: the measure creates short-term demand for replacement units and authorised maintenance, but does not, on its face, change market structure or competition beyond that effect.\n\n**Notes on the document itself**\n\n- The AD sets out the unsafe condition and the affected serial/part numbers and states that corrective action is required; the exact corrective steps and timing are described in the AD requirement section (not reproduced here).  The legal basis cited is subregulation 39.1(1) of CASR 1998.\n\n(Plain-language summary prepared as an analyst's note: factual description of the AD’s mechanics, the parties it affects, and the likely practical costs and incentives. The AD’s full operational requirements and compliance timing must be read in the AD’s requirement and compliance sections for action.)"},"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-rad-83-honeywell-mst-67a-transponder","history":"/api/acts/ad-rad-83-honeywell-mst-67a-transponder/history","analysis":"/api/acts/ad-rad-83-honeywell-mst-67a-transponder/analysis","conflicts":"/api/acts/ad-rad-83-honeywell-mst-67a-transponder/conflicts","importantCases":"/api/acts/ad-rad-83-honeywell-mst-67a-transponder/important-cases","documents":"/api/acts/ad-rad-83-honeywell-mst-67a-transponder/documents"}}