{"id":"F2006B09252","name":"AD/DHC-8/92 - RDS86 Weather Radar Circuit Breakers","slug":"ad-dhc-8-92-rds86-weather-radar-circuit-breakers","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":53196,"registerId":"commonwealth-F2006B09252-current","compilationNumber":null,"startDate":"2026-04-02","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\nBombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/DHC-8/92 RDS86 Weather Radar Circuit ","sectionType":"part","heading":"AD/DHC-8/92 RDS86 Weather Radar Circuit Breakers 7/2003","content":"# AD/DHC-8/92 RDS86 Weather Radar Circuit Breakers 7/2003\n\nApplicability: DHC-8 Model 102 aircraft, serial numbers 023 through 392, equipped with RDS86 Weather Radar System but excluding those aircraft equipped with option CR834CH00284.\n\nRequirement: For aircraft with options CSI 82309, CR834CH82309 or CR811CH82309 incorporated \\- Modify the electrical power circuit in accordance with the procedures detailed in paragraph 2.2 of Bombardier ModSum IS8Q3450000 by replacing the 7.5 amp circuit breaker with a 5 amp breaker and installing an additional 3 amp breaker.\n\nFor aircraft without options CSI 82309, CR834CH82309 or CR811CH82309 incorporated \\- Modify the electrical power circuit in accordance with the procedures detailed in paragraph 2.3 of ModSum IS8Q3450000 by replacing the 7.5 amp circuit breaker with a 5 amp breaker and installing an additional 3 amp breaker.\n\nNote: Transport Canada AD CF-2003-13 refers.\n\nCompliance: Within twelve months after the effective date of this Directive.\n\nThis Airworthiness Directive becomes effective on 10 July 2003.\n\nBackground: Overheating of the radar ribbon cable and/or the radar indicator can result in smoke in the cockpit. The overheating can occur because the 7.5 amp circuit breaker installed for both the radar transmitter and radar indicator does not provide adequate protection in the event of a short circuit within the radar indicator.\n\n![](image.002.png)  \n\nJim Coyne\n\nDelegate of the Civil Aviation Safety Authority 30 May 2003\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 18 June 2003.","sortOrder":1}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD is narrowly focused on correcting an identified electrical protection deficiency in the RDS86 weather radar installation on a defined set of DHC-8 Model 102 airframes. It does not expand beyond that original safety fixing purpose: the requirement is limited to replacing and adding circuit breakers per Bombardier’s ModSum and applies only to the specified serial-numbered aircraft with the RDS86 system (excluding those with a specific option). There is no indication in the text that the scope was broadened beyond that technical safety objective."},"complexity_factors":["Short document with a single clear safety remedy","One conditional branch: two different ModSum paragraphs to follow depending on whether options CSI 82309, CR834CH82309 or CR811CH82309 are incorporated","Narrow applicability: specific aircraft model and serial number range (023–392) with a single equipment fitment (RDS86), plus an exclusion for option CR834CH00284","Cross-reference to external technical instructions (Bombardier ModSum IS8Q3450000) which contain the detailed procedures","Cross-reference to a foreign regulator's AD (Transport Canada AD CF-2003-13) in the Note","Single compliance deadline (12 months) and a clear required action (breaker replacement and addition)"],"plain_english_summary":"**What this directive does (mechanics)\n\n- Applies to: Bombardier (De Havilland) DHC-8 Model 102 aeroplanes, serial numbers 023 through 392, that are fitted with the RDS86 weather radar system. Aircraft fitted with option CR834CH00284 are excluded. (See the Applicability section.)\n\n- Required action: Modify the electrical power circuit for the radar system by replacing an existing 7.5 amp circuit breaker with a 5 amp circuit breaker and installing an additional 3 amp breaker. The exact procedure to follow is the Bombardier modification summary (ModSum IS8Q3450000): use paragraph 2.2 if the aircraft has options CSI 82309, CR834CH82309 or CR811CH82309; use paragraph 2.3 if those options are not present. (See the Requirement section.)\n\n- Timing: The modification must be completed within 12 months of the AD’s effective date. (See the Compliance section.)\n\n- Who issued it: The Civil Aviation Safety Authority delegate issued the directive requiring the modification. (See the heading and signature block.)\n\nWhy the directive exists (stated safety concern)\n\n- The Background section says the single 7.5 amp circuit breaker that protected both the radar transmitter and the radar indicator did not always provide adequate protection for a short circuit occurring inside the radar indicator. That short-circuit risk can cause overheating of the radar ribbon cable and/or the radar indicator, and that overheating has produced smoke in the cockpit. The modification separates and reduces circuit breaker ratings to give better protection.\n\nWho is affected and who pays\n\n- Affected parties: Aircraft owners/operators of the specified DHC-8 Model 102 airframes that have the RDS86 radar (except those with option CR834CH00284). Maintenance organisations and engineers performing the work are also involved because the ModSum procedures must be followed.\n\n- Who pays: The aircraft owner/operator will bear the direct cost (parts and maintenance labour) and aircraft downtime required to perform the modification. The AD does not specify funding or compensation.\n\nPractical effects and implementation considerations\n\n- Behavioural change: Operators must schedule and complete the electrical modification for each affected aircraft within the 12‑month compliance window.\n\n- Work required: The modification is technical and must be carried out in accordance with the Bombardier ModSum instructions (paragraph 2.2 or 2.3, as applicable). That typically requires qualified maintenance personnel and the specified replacement circuit breakers and associated hardware.\n\n- Compliance burden and downtime: The AD creates a compliance cost (parts and labour) and aircraft downtime for each affected aeroplane. The AD does not provide an alternative means of compliance (AMOC) within the text; any AMOC would need to be approved through the regulator’s normal processes.\n\n- Market and competition effects: The directive imposes the same technical requirement on all affected operators; it does not grant exclusive rights or authorisations to particular service providers. Availability of parts or Bombardier repair documentation could create short-term supply pressure for maintenance shops that service this model.\n\n- Enforcement and discretion: The AD is a mandatory safety requirement issued by the CASA delegate under CASR subregulation 39.1(1). The regulator may accept alternative methods only through its formal approval processes; the AD itself sets the required modification and compliance date.\n\nSource-attributed purpose claim and testing against trade-offs\n\n- The AD’s stated purpose is to reduce the chance of overheating and cockpit smoke by improving circuit protection (Background section). Mechanically, it does so by lowering one breaker rating and adding a second breaker so that the radar transmitter and indicator have improved short-circuit protection. The trade-offs are concrete: operators pay for parts and labour and accept aircraft downtime; the AD does not prescribe additional operational restrictions or recurring costs beyond the one-time modification. The AD relies on Bombardier’s ModSum for technical details, so timely access to that documentation and to the specified replacement parts is necessary to implement the mandated change.\n\n(References: Applicability, Requirement, Compliance, Background sections of the AD.)"},"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":3,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope. It addresses a specific unsafe condition in a specific aircraft model's weather radar electrical system. The two-tier requirement structure (with/without certain factory options) reflects manufacturing variations rather than scope creep. The directive remains tightly focused on the circuit breaker modification to prevent radar overheating."},"complexity_factors":["Short document (approximately 300 words)","Only 4 defined applicability criteria (model, serial range, equipment type, exclusion option)","Two parallel requirement paths based on factory option codes, but both lead to essentially the same physical modification","Single cross-reference to Canadian aviation authority (Transport Canada AD CF-2003-13)","No nested exceptions or conditional logic beyond the initial applicability filter","Clear compliance deadline (12 months from effective date)","Technical terminology is aircraft-specific but explained through context (circuit breaker functions, ModSum reference)"],"plain_english_summary":"This CASA Airworthiness Directive mandates electrical changes to certain Bombardier DHC‑8 Model 102 (serials 023–392) fitted with the RDS86 weather radar to eliminate a cockpit smoke/fire risk. Operators must replace the slow 7.5 A circuit breaker with a 5 A breaker and add a new 3 A breaker (with one option-code exclusion), following Bombardier instructions. Compliance was required within 12 months of 10 July 2003."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-8-92-rds86-weather-radar-circuit-breakers","history":"/api/acts/ad-dhc-8-92-rds86-weather-radar-circuit-breakers/history","analysis":"/api/acts/ad-dhc-8-92-rds86-weather-radar-circuit-breakers/analysis","conflicts":"/api/acts/ad-dhc-8-92-rds86-weather-radar-circuit-breakers/conflicts","importantCases":"/api/acts/ad-dhc-8-92-rds86-weather-radar-circuit-breakers/important-cases","documents":"/api/acts/ad-dhc-8-92-rds86-weather-radar-circuit-breakers/documents"}}