{"id":"F2006B06519","name":"AD/RAD/65 - VN 411B VHF Navigation Receiver","slug":"ad-rad-65-vn-411b-vhf-navigation-receiver","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":48127,"registerId":"commonwealth-F2006B06519-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/RAD/65 - VN 411B VHF Navigation Receiver","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 107 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nRadio Communication and Navigation Equipment\n\nAD/RAD/65 VN 411B VHF Navigation Receiver 8/99\n\nApplicability: AlliedSignal (formerly Bendix and Bendix/King) VN 411B Very High frequency (VHF) Navigation Receivers as follows:\n\nBPN 3614004-4101 \\- all serial numbers, at Modification Status 18, 19 or 20;\n\nBPN/KPN 3614004-4101/066-1101-00 \\- all serial numbers, at Modification Status 18, 19 or 20;\n\nP/N 066-1101-00 \\- serial numbers up to and including 4229, at Modification Status 18, 19 or 20; and\n\nP/N 066-1101-31, \\-40 or \\-50 \\- serial numbers up to and including 10799, at Modification Status 19 or 20.\n\nNote: These VHF Navigation Receivers are known to be fitted to, but not limited to, the following aircraft models:\n\nLearjet 31A Fokker F27-50 BAe ATP\n\nRequirement: 1. Incorporate Modification 21 in accordance with either AlliedSignal Aerospace, Commercial Avionics Systems, Bendix/King Service Bulletin (SB) VN 411B-21 dated November 1996 or SB VN 411-21 Revision 1 dated April 1997.\n\n2. VN 411 VHF Navigation Receivers listed in the Applicability Statement of this Directive that do not have Modification 21 incorporated must not be installed on any aeroplane.\n\nNote: FAA AD 99-12-06 Amdt 39-11190 refers.\n\nCompliance: 1. Either, within 90 calendar days after the effective date of this Directive or upon replacement or repair of the VHF Navigation Receiver, whichever occurs first.\n\n2. As of the effective date of this Directive.\n\nThis Airworthiness Directive becomes effective on 12 August 1999.\n\nBackground: The United States Federal Aviation Administration has received reports of interference to the navigation receiver during landing operations. This Directive is intended to prevent interference from frequency modulated radio stations, which could cause both distortion of the navigation audio and deflection from the desired flight path.","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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This directive stays within the single, stated purpose: mitigate FM radio interference to VN 411B navigation receivers by mandating Modification 21 and banning unmodified installations. It does not broaden regulatory scope beyond fixing the specific equipment problem described in the Background or introduce unrelated obligations."},"complexity_factors":["Short, single‑issue Airworthiness Directive focused on one modification","Applicability lists multiple part numbers and serial number cut‑offs (several lines to check)","Two clear requirements (modify to Mod 21; ban unmodified installations)","Two compliance rules (90 calendar days or upon replacement/repair; installation ban effective immediately)","Cross‑reference to FAA AD (external reference but not a complex regulatory network)","Few conditional branches or nested exceptions"],"plain_english_summary":"**What the rule does (mechanically)**\n\n- Requires that certain AlliedSignal (formerly Bendix/Bendix‑King) VN 411B VHF navigation receivers be modified to \"Modification 21\" in accordance with the manufacturer's Service Bulletin (SB VN 411B‑21 or VN 411‑21 Rev 1). (Requirement 1)\n- Prohibits installing any receiver listed in the Applicability section on an aircraft unless it already has Modification 21. (Requirement 2)\n- Sets the deadline: receivers must have the modification either within 90 calendar days after the directive takes effect, or sooner if the receiver is replaced or repaired (whichever happens first). (Compliance 1)\n- The prohibition on installing unmodified receivers applies immediately from the effective date. (Compliance 2)\n\n**Who this affects**\n\n- Aircraft owners/operators and operators of aircraft types known to carry these receivers (examples listed: Learjet 31A, Fokker F27‑50, BAe ATP). (Applicability)\n- Maintenance organisations, avionics shops and certificated repair stations that service, repair or install VN 411B receivers.\n- Parts suppliers and stock managers who handle VN 411B units or replacement units.\n\n**Why it matters (stated purpose and operational effect)**\n\n- The directive responds to reports of interference to the navigation receiver during landing operations caused by frequency‑modulated (FM) radio stations. The interference can distort navigation audio and cause course deflection during critical flight phases (Background).\n- Mechanically: operators must ensure units are modified to a standard (Modification 21) that mitigates that FM interference, and cannot fit unmodified units to aircraft after the directive takes effect. (Requirement 1–2)\n\n**Who pays, who decides, and how behaviour changes**\n\n- Operators/owners pay for the modification work (parts, labour, aircraft downtime) or for replacing/repairing units so the modification is applied. Maintenance organisations perform the work following the manufacturer's Service Bulletin. (Requirement 1; Compliance 1)\n- Regulators (the Civil Aviation Safety Authority, via this Airworthiness Directive) decide the compliance requirement and effective date; manufacturers provide the technical procedure (Service Bulletin) that must be followed. (Directive text; Requirement 1)\n- Behaviour changes: aircraft cannot accept an unmodified VN 411B listed in the Applicability; operators must schedule modification work within 90 days or before any replacement/repair event, and maintenance providers must apply the specified SB procedures.\n\n**Costs, incentives and trade‑offs**\n\n- Immediate compliance cost: modification labour and parts plus aircraft downtime. The 90‑day window compresses scheduling for operators with many affected units.\n- Replacement/repair incentive: because compliance is also triggered on replacement or repair, operators who delay may face higher costs if a failure occurs and a unit must be removed and modified/replaced immediately.\n- Supply/implementation risk: if many operators require the modification in a short period, certified parts or authorised maintenance slots could be constrained (implementation burden for operators and maintenance providers).\n- Market effect: the modification work creates demand for authorised service providers and parts; the manufacturer (or authorised repair stations) capture the technical service market for the SB work. Independent shops can perform the work only if they meet the certification/technical requirements in the SB and regulatory approval.\n- Compliance monitoring: operators bear the recordkeeping and proof obligations that the installed unit is at Modification 21 when inspected.\n\n**Cross‑references and harmonisation**\n\n- The directive notes a corresponding FAA Airworthiness Directive (FAA AD 99‑12‑06), indicating the action aligns with the U.S. regulator's response to the same problem (Note).\n\n**Net operational effect**\n\n- The directive narrows permitted equipment: affected VN 411B units must be at Modification 21 to be installed or remain installed after the compliance window. This reduces the risk of FM interference during landing at the cost of modification expense and operational downtime.\n\n(References in parentheses refer to the sections of the directive: Applicability; Requirement 1–2; Compliance 1–2; Background.)"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific equipment defect. It has not expanded beyond its original purpose of mandating a specific modification to prevent navigation interference."},"complexity_factors":["Specific part number and serial number ranges create narrow applicability (4 distinct product categories)","References to external manufacturer service bulletins (SB VN 411B-21 and SB VN 411-21 Rev 1) without reproducing their content","Dual compliance pathways (90-day window OR upon replacement/repair)","Cross-reference to US FAA AD 99-12-06 for additional context","Technical aviation terminology requiring domain knowledge (BPN, KPN, P/N, Modification Status)"],"plain_english_summary":"CASA orders mandatory modification (‘‘Modification 21’’) of certain AlliedSignal/Bendix/King VN 411B VHF navigation receivers because FM radio interference can distort audio and give incorrect navigation readings during landing. After the effective date, unmodified receivers may not be installed.\n\nThis affects operators and maintenance organisations for aircraft types using these units (e.g., Learjet 31A, Fokker F27-50, BAe ATP) and pilots relying on them — addressing a serious safety risk during a critical flight phase."}},"importantCases":[],"_links":{"self":"/api/acts/ad-rad-65-vn-411b-vhf-navigation-receiver","history":"/api/acts/ad-rad-65-vn-411b-vhf-navigation-receiver/history","analysis":"/api/acts/ad-rad-65-vn-411b-vhf-navigation-receiver/analysis","conflicts":"/api/acts/ad-rad-65-vn-411b-vhf-navigation-receiver/conflicts","importantCases":"/api/acts/ad-rad-65-vn-411b-vhf-navigation-receiver/important-cases","documents":"/api/acts/ad-rad-65-vn-411b-vhf-navigation-receiver/documents"}}