{"id":"F2006B02515","name":"AD/AS 355/65 Amdt 1 - Horizontal Situation Indicator","slug":"ad-as-355-65-amdt-1-horizontal-situation-indicator","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41771,"registerId":"commonwealth-F2006B02515-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AS 355/65 Amdt 1 - Horizontal Situation Indicator","content":"![](image.001.png)\n\nAIRWORTHINESS DIRECTIVE\n\n![](image.001.png)  \n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/AS 355/65 and issues the following 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\nEurocopter AS 355 (Twin Ecureuil) Series Helicopters\n\nAD/AS 355/65\n\nAmdt 1\n\n  \nHorizontal Situation Indicator 6/2004\n\nApplicability: AS 355 helicopters Versions E, F, F1, F2 and N equipped with Bendix/King KI 525A Horizontal Situation Indicator (HSI).\n\nRequirement: 1. Check the part number (P/N) of the KI 525A HSI installed on the helicopter.\n\nInitially, no further action is necessary if the P/N is not 066-3046-07.\n\n    2. If the P/N is 066-3046-07, modify the HSI installation in accordance with Eurocopter Alert Telex 34.00.09 paragraph 2.A.1, for helicopters with the HSI connected to a single navigation system, or paragraph 2.A.2, for helicopters with the HSI connected to at least two navigation systems.\n\nNote 1: Modification ion accordance with Eurocopter Alert Service Bulletin (ASB)\n\n34.00.09 is considered acceptable for compliance with Requirement 2.\n\n    3. Before installing a KI 525A HSI P/N 066-3046-07 in place of a KI 525A HSI with P/Ns 066-3046-00, -01, -04 or -05 ensure that the HSI installation is modified in accordance with Requirement 2.\n\nNote 2: DGAC AD F-2002-280-068 R1 refers.\n\nCompliance: For Requirement 1 \\- Remains unchanged as ‘Either within 100 hours time in service after the effective date of the original issue of this Directive or before 10 August 2003, whichever occurs first’.\n\nFor Requirement 2 \\- Before further flight after the Requirement 1 check. For Requirement 3 - As of the effective date of this Amendment.\n\nThis Amendment becomes effective on 10 June 2004.\n\nBackground: Eurocopter has advised the French Direction Générale de l’Aviation Civile that KI 525A HSIs P/N 066-3046-07 may have been incorrectly installed on some helicopters. The incorrect installation may result in navigation errors.\n\nThe original issue of this Directive introduced measures to ensure that the affected HSIs were correctly installed.\n\nEurocopter AS 355 (Twin Ecureuil) Series Helicopters\n\nAD/AS 355/65 Amdt 1 (continued)\n\nThis Amendment contains some minor editorial amendments, together with allowing credit for modifications carried out in accordance with the ASB and introduces measures to ensure that the helicopter is modified prior to the installation of a\n\nKI 525A HSI P/N 066-3046-07.\n\nThe original issue of this Airworthiness Directive became effective on 5 June 2003.\n\n![](image.002.png)  \n\nJames Coyne\n\nDelegate of the Civil Aviation Safety Authority 30 April 2004\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 19 May 2004.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This Amendment makes limited, targeted changes to the original AD rather than expanding its mission. It (a) adds editorial clarifications, (b) expressly allows credit for modifications already carried out in accordance with Eurocopter ASB 34.00.09, and (c) introduces a requirement that installations be modified before installing KI 525A HSI P/N 066-3046-07 as a replacement. Those adjustments sharpen implementation and pre-install controls but do not significantly broaden the AD’s original safety purpose of ensuring correct HSI installation to avoid navigation errors."},"complexity_factors":["Short, single-aircraft-model scope (AS 355 versions E, F, F1, F2, N)","Three numbered substantive requirements (P/N check; modification; pre-install prohibition)","Conditional logic based on part number (P/N 066-3046-07)","Two alternative modification procedures depending on number of connected navigation systems (paragraphs 2.A.1 vs 2.A.2)","Cross-reference to Eurocopter Alert Telex 34.00.09 and acceptance of Eurocopter ASB 34.00.09 for compliance","References to an external foreign AD (DGAC AD F-2002-280-068 R1)","Timing conditions in the Compliance section referencing prior effective-date deadlines"],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- It is an Airworthiness Directive (AD) that applies to Eurocopter AS 355 (Twin Ecureuil) helicopters of versions E, F, F1, F2 and N when they are fitted with a Bendix/King KI 525A Horizontal Situation Indicator (HSI).\n- The AD requires operators to:  \n  1. Check the part number (P/N) of the installed KI 525A HSI (Requirement 1). If the HSI is not P/N 066-3046-07, no further action under this AD is needed.  \n  2. If the HSI is P/N 066-3046-07, modify the HSI installation in accordance with Eurocopter Alert Telex 34.00.09: paragraph 2.A.1 where the HSI is connected to a single navigation system, or paragraph 2.A.2 where it is connected to at least two navigation systems (Requirement 2). The AD explicitly accepts compliance carried out in accordance with Eurocopter Alert Service Bulletin (ASB) 34.00.09 (Note 1).  \n  3. Before installing a KI 525A HSI with P/N 066-3046-07 as a replacement for earlier P/Ns (066-3046-00, -01, -04 or -05), ensure the installation has been modified as required in Requirement 2 (Requirement 3).\n- Timing/Compliance:  \n  - The initial P/N check (Requirement 1) had to be done within the timeframe set out in the original AD (either within 100 hours time in service after that AD’s effective date or before 10 August 2003, whichever came first).  \n  - If the HSI is the affected P/N, the modification (Requirement 2) must be carried out before further flight after the P/N check.  \n  - The prohibition on installing an unmodified P/N 066-3046-07 in place of earlier P/Ns (Requirement 3) took effect from this Amendment’s effective date.\n\n**Who this affects**\n\n- Aircraft operators/owners of Eurocopter AS 355 helicopters versions E, F, F1, F2 and N fitted with Bendix/King KI 525A HSIs.  \n- Maintenance organisations and licensed engineers who perform inspections, electrical/hardware modifications and installations on those HSIs.  \n- Suppliers/parts managers: replacement HSIs of P/N 066-3046-07 may not be installed unless the installation is modified per the AD.\n\n**Why it matters (purpose claim and practical consequences)**\n\n- The stated rationale (Background) is that some KI 525A HSIs P/N 066-3046-07 may have been incorrectly installed, which can cause navigation errors. The AD’s mechanics are intended to detect installations with that P/N and ensure the installation wiring/arrangement is modified so the instrument functions correctly.\n\n- Who pays: operators bear the direct costs (inspection labour, modification labour, parts if needed, aircraft downtime). Maintenance providers absorb the labour input; in practice those costs are passed to operators under service/maintenance contracts.\n\n- Who decides and who implements: the CASA delegate issues the AD; Eurocopter’s Alert Telex/ASB sets the technical steps for modification; licensed maintenance organisations implement the work and determine scheduling within the AD’s compliance windows.\n\n**Practical trade-offs, compliance issues and risks**\n\n- Compliance burden: requires at least one P/N check per affected helicopter and, for affected units, immediate modification before further flight. That imposes aircraft downtime and maintenance resource use. Requirement 3 also prevents installing the affected P/N in the future unless the installation is modified first.\n\n- Implementation risk: correct compliance depends on following Eurocopter Alert Telex 34.00.09 or ASB 34.00.09 precisely. Accepting ASB compliance provides a clear technical standard, reducing ambiguity for maintenance organisations.\n\n- Opportunity cost: time and money spent on the modification are resources not available for other maintenance or operations.\n\n- Effects on private choice and markets: the AD constrains operators’ freedom to install a specific HSI P/N without performing the modification first. This may affect parts inventory decisions and timing of avionics upgrades.\n\n- Concentrated benefits and diffuse costs: the safety benefit (reduced navigation error risk) accrues to operators, crews, and passengers of affected helicopters; the costs are concentrated on those same operators and their maintenance suppliers.\n\n**Relevant provisions cited**\n\n- Requirement 1 (P/N check), Requirement 2 (modify per Eurocopter Alert Telex 34.00.09 / ASB 34.00.09), Requirement 3 (pre-installation modification requirement), Note 1 (ASB acceptable for compliance), Note 2 (DGAC AD reference), Compliance section (timing), Background (reason for AD)."},"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 Amendment 1 stays true to the original purpose of ensuring correct installation of the KI 525A HSI. It adds one preventive measure (Requirement 3 — ensuring modification before installation of the affected part) and allows credit for work already done per the Alert Service Bulletin, but does not expand beyond the original safety issue of incorrect HSI installation."},"complexity_factors":["Single specific aircraft type and limited part number range (P/N 066-3046-07)","Only 3 requirements with clear conditional logic (if/then structure)","Straightforward compliance timeline with specific dates","Cross-reference to external technical document (Eurocopter Alert Telex 34.00.09) but provides acceptable alternative compliance path (ASB 34.00.09)","Single reference to foreign aviation authority (DGAC AD F-2002-280-068 R1) in a non-binding note","No nested definitions or interpretation section","Amendment structure is simple: revokes previous AD, issues new one with minor editorial changes plus one new preventive requirement (Requirement 3)"],"plain_english_summary":"This AD requires owners/operators of Eurocopter AS 355 E/F/F1/F2/N helicopters equipped with Bendix/King KI 525A HSI (P/N 066-3046-07) to inspect the installation and, if incorrect, modify it per Eurocopter instructions. Any replacement of that HSI must be modified before installation.\n\nThe measure prevents false navigation indications that could cause CFIT, airspace violations, or mid‑air collisions. The inspection deadline was August 2003 or within 100 flight hours; required modifications must be completed before next flight."}},"importantCases":[],"_links":{"self":"/api/acts/ad-as-355-65-amdt-1-horizontal-situation-indicator","history":"/api/acts/ad-as-355-65-amdt-1-horizontal-situation-indicator/history","analysis":"/api/acts/ad-as-355-65-amdt-1-horizontal-situation-indicator/analysis","conflicts":"/api/acts/ad-as-355-65-amdt-1-horizontal-situation-indicator/conflicts","importantCases":"/api/acts/ad-as-355-65-amdt-1-horizontal-situation-indicator/important-cases","documents":"/api/acts/ad-as-355-65-amdt-1-horizontal-situation-indicator/documents"}}