{"id":"F2006B03640","name":"AD/BEECH 1900/23 - Radio Switching Panel","slug":"ad-beech-1900-23-radio-switching-panel","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43230,"registerId":"commonwealth-F2006B03640-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BEECH 1900/23 - Radio Switching Panel","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nBeechcraft 1900 Series Aeroplanes\n\nAD/BEECH 1900/23 Radio Switching Panel 7/98\n\nApplicability: Model 1900D aeroplanes with serial numbers UE-1 through UE-160 inclusive.\n\nRequirement: 1. Inspect the radio switching panel, the electrical connectors and the relay printed circuit board (PCB) for moisture or corrosion in accordance with the Accomplishment Instructions of Raytheon Service Bulletin (SB) 2643 dated August 1996.\n\n    2. If moisture and/or corrosion is found during the Requirement 1 inspection, carry out the following actions:\n\n    moisture is found \\- clean and dry the component in accordance with SB 2643, then locate and eliminate the source of the moisture.\n\n    b. corrosion is found \\- either clean or replace the component in accordance with SB 2643, then locate and eliminate the cause of the corrosion.\n\n    3. Inspect the nose avionics wire harnesses for proper installation in accordance with SB 2643.\n\n    4. If any harness is found to be incorrectly installed during the Requirement 3 inspection, secure it with cable ties in accordance with SB 2643.\n\n    5. Remove the A017 component PCB part number (P/N) 101-342536-1 and replace it with a new A017 component PCB P/N 101-342536-5, in accordance with SB 2643.\n\nNote: FAA AD 98-09-12 Amdt 39-10493 refers.\n\nCompliance: 1. Within the next 1000 hours time in service after the effective date of this directive, but no later than 12 November 1998.\n\n    2. Prior to further flight, immediately after the Requirement 1 inspection.\n\n    3. Within the next 1000 hours time in service after the effective date of this directive, but no later than 12 November 1998.\n\n    4. Prior to further flight, immediately after the Requirement 3 inspection.\n\n    5. Within the next 1000 hours time in service after the effective date of this directive, but no later than 12 November 1998.\n\nThis airworthiness directive becomes effective on 18 June 1998.\n\nBackground: The FAA has received several reports of loss of the pilot/copilot intercom system, VHF communication system and passenger address system. This directive specifies actions which are designed to decrease the likelihood of failure of these systems, which could result in loss of all communication during critical phases of flight.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES","sortOrder":0}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This airworthiness directive maintains its original narrow scope. It addresses a specific safety issue (radio system failures) in a specific aircraft model range through targeted inspections and component replacement. There is no evidence of scope creep beyond the original safety purpose."},"complexity_factors":["Short, single-purpose directive with only 5 numbered requirements","Minimal defined terms (only specific part numbers and serial numbers)","Simple conditional logic (if moisture found → clean; if corrosion found → clean or replace)","Clear compliance deadlines with specific dates and flight hour limits","Single cross-reference to FAA AD 98-09-12 and Raytheon Service Bulletin 2643","No nested exceptions or complex interpretive provisions"],"plain_english_summary":"This CASA safety order requires owners/operators of Beechcraft 1900D aircraft (serials UE-1 to UE-160) to inspect the radio switching panel, connectors, circuit boards and nose wiring for moisture/corrosion, and to clean, dry, repair or replace affected parts. It aims to prevent in‑flight loss of intercom, radios and PA systems. Any defects found must be rectified before further flight; many tasks must be completed within 1,000 flight hours or by 12 November 1998."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive stays within the original safety-focused purpose: identify and remedy moisture/corrosion and a suspect PCB in the radio switching system to reduce loss of communications. It does not expand beyond that technical remedial scope (inspections, repairs, securing harnesses, and a specified part replacement) and therefore has not materially changed scope from its stated intent."},"complexity_factors":["Single-aircraft model applicability limited to serial numbers UE-1 through UE-160","Five discrete requirements (inspections, conditional remedies, harness check, securing, PCB replacement)","Cross-reference to an external technical document: Raytheon Service Bulletin (SB) 2643 for procedural detail","Specific part numbers required for replacement (P/N 101-342536-1 replaced by P/N 101-342536-5)","Multiple compliance timings: ‘‘within 1,000 hours or by 12 Nov 1998’’ and immediate ‘‘prior to further flight’’ conditions","Conditional remedial paths (moisture -> clean/dry; corrosion -> clean or replace)"],"plain_english_summary":"**What this instrument requires (mechanical changes)**\n\n- Applies to Beechcraft 1900D aeroplanes with serial numbers UE-1 through UE-160 (Requirement: Applicability).\n- Requires operators to inspect the radio switching panel, its electrical connectors and the relay printed circuit board (PCB) for moisture or corrosion, using the procedures in Raytheon Service Bulletin (SB) 2643 (Requirement 1).\n- If moisture is found, the component must be cleaned and dried and the source of moisture located and eliminated (Requirement 2a).\n- If corrosion is found, the component must be either cleaned or replaced and the cause of the corrosion located and eliminated (Requirement 2b).\n- Requires inspection of the nose avionics wire harnesses for correct installation, again per SB 2643 (Requirement 3).\n- If a harness is incorrectly installed, it must be secured with cable ties per SB 2643 before further flight (Requirement 4).\n- Requires replacement of the A017 relay PCB P/N 101-342536-1 with new PCB P/N 101-342536-5 in accordance with SB 2643 (Requirement 5).\n- Compliance timing: most inspections and the PCB replacement must be completed within the next 1,000 flight hours or by 12 November 1998 (whichever comes first); corrective actions that are discovered during inspections that affect safety must be done before further flight (Compliance).\n\n**Who is affected and who pays**\n\n- Aircraft operators and owners of the specified Beechcraft 1900D serial-number range are directly affected: they must arrange inspections, repairs, and the PCB replacement and bear the costs of labour, parts and any aircraft downtime.\n- Maintenance organisations (in-house or independent repair stations) will perform the mandated work and therefore may receive the business; parts suppliers producing the specified PCB will supply the replacement component (Requirement 5 and SB 2643).\n\n**Why it matters (stated purpose and mechanical effect)**\n\n- The directive cites FAA reports of multiple incidents of loss of pilot/copilot intercom, VHF communications and passenger address systems. It states its purpose as reducing the likelihood of such failures which could otherwise lead to total loss of communications during critical flight phases (Background).\n- Mechanically, it forces a set of inspections and remedial actions targeted at moisture and corrosion in the radio switching panel and related wiring, and mandates replacement of a specific PCB thought to be implicated in the failures.\n\n**Testing the stated purpose against practical effects, costs and trade-offs**\n\n- Direct effect on safety mechanism: By requiring inspection/cleaning/correction of moisture and corrosion and replacing a particular relay PCB, the instrument targets potential failure modes for multiple communication systems (Requirements 1–5).\n- Costs and who bears them: Operators pay for inspection labour, possible cleaning, replacement parts (the new PCB), and aircraft downtime while work is carried out. These are immediate, tangible costs imposed on operators (Compliance; Requirements 2 and 5).\n- Incentives and substitution effects: Operators have an incentive to complete inspections within the compliance window. If parts are hard to obtain or expensive, operators may face grounding or choose temporary mitigation (e.g., more frequent inspections) where permitted. Independent maintenance providers gain business from required work.\n- Implementation risk and compliance burden: The AD cross-references Raytheon SB 2643 for procedural detail; compliance depends on access to that SB and the specified replacement PCB. The directive imposes both a time-based deadline (1,000 hours or date) and immediate ‘‘prior to further flight’’ obligations where defects are found, increasing operational urgency (Compliance; Requirements 2 and 4).\n- Bureaucratic discretion: The AD prescribes actions and references a manufacturer service bulletin for technical detail; it leaves limited discretionary choice to operators beyond selecting whether to clean or replace corroded components (Requirement 2b). The regulator enforces compliance but does not provide alternative technical procedures except via the SB.\n- Effects on private choice, competition and markets: The requirement to use SB 2643 procedures and to install a specific replacement PCB (P/N 101-342536-5) channels demand to the OEM/methodology identified by the SB (Requirement 5). This concentrates demand for the specified part and authorised repair procedures, which benefits suppliers/manufacturer and maintenance providers familiar with the SB. There is no change to ownership or contractual freedom beyond mandatory compliance with the AD.\n- Opportunity costs: Time and money spent complying are not available for other upgrades or maintenance. If multiple aircraft in a fleet require the work simultaneously, operators may need short-term capacity or schedule adjustments.\n\n**Concentrated benefits, diffuse costs and potential for supplier advantage**\n\n- The AD’s prescription of a specific replacement PCB and reliance on a manufacturer service bulletin creates a concentrated benefit to the party supplying that PCB and to maintenance organisations competent with SB 2643 (Requirement 5 and cross-reference to SB 2643). The source document itself supports this link by naming the SB and the part numbers.\n- The costs (inspection, parts, downtime) are dispersed across multiple operators of the affected serial-numbered aircraft.\n\n**Practical operational consequence**\n\n- Aircraft found with moisture or corrosion in the inspected components may be grounded until cleaning/repair/replacement and elimination of the cause is completed. That is explicit for defects discovered during inspection (Compliance: ‘‘prior to further flight’’ for Requirements 2 and 4).\n\n**Source-cited provisions**\n\n- Inspections: Requirement 1 and Requirement 3.\n- Remedial actions for moisture/corrosion: Requirement 2 (a and b).\n- Harness securing: Requirement 4.\n- PCB replacement and part numbers: Requirement 5.\n- Compliance timings and ‘‘prior to further flight’’ obligations: Compliance section.\n- Stated rationale (FAA reports of communication loss): Background.\n\n"}},"importantCases":[],"_links":{"self":"/api/acts/ad-beech-1900-23-radio-switching-panel","history":"/api/acts/ad-beech-1900-23-radio-switching-panel/history","analysis":"/api/acts/ad-beech-1900-23-radio-switching-panel/analysis","conflicts":"/api/acts/ad-beech-1900-23-radio-switching-panel/conflicts","importantCases":"/api/acts/ad-beech-1900-23-radio-switching-panel/important-cases","documents":"/api/acts/ad-beech-1900-23-radio-switching-panel/documents"}}