{"id":"F2006B02495","name":"AD/AS 355/41 Amdt 1 - Main Rotor Pitch Change Horn Bushes","slug":"ad-as-355-41-amdt-1-main-rotor-pitch-change-horn-bushes","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41751,"registerId":"commonwealth-F2006B02495-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AS 355/41 Amdt 1 - Main Rotor Pitch Change Horn Bushes","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)  \nEurocopter AS 355 (Twin Ecureuil) Series Helicopters\n\nAD/AS 355/41\n\nAmdt 1\n\n  \nMain Rotor Pitch Change Horn Bushes 7/93\n\nDM\n\nApplicability: Models E, F, F1, F2, and N fitted with pitch change horns P/N 350A31-1877-02 that are not marked with an ‘X’ after the part number, and have a serial number less than 100-000.\n\nRequirement: Action in accordance with Eurocopter SB AS355 62.24 R1.\n\nNote: DGAC AD 92-183-046(B)R1 refers.\n\nCompliance: 1. Paragraph 1.C.1.: Within 50 hours time in service after 12 May 1993, and\n\n2. If required, paragraph 1.C.2.b: within 300 hours time in service after 12 May 1993\\. The effective date of the initial issue of this Directive was 12 November 1992.\n\nBackground: The initial issue of the Directive was due to the discovery of pitch change horn bushes that were incorrectly tapered and could possibly cause failure of the pitch change horn to rod connecting bolt. Amendment 1 revises Applicability to include all pitch change horn serial numbers to 100-000.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":true,"description":"The original directive (issued November 1992) had narrower applicability. Amendment 1 explicitly expands the scope to include 'all pitch change horn serial numbers to 100-000' — broadening the safety net to capture more potentially defective components than the initial issue covered. This is a modest scope expansion typical of aviation safety evolution, not a fundamental mission creep."},"complexity_factors":["Single, specific technical subject matter (one helicopter part)","Limited applicability criteria (5 model variants, specific part number, serial number range, marking exclusion)","Simple two-stage compliance structure (initial inspection + conditional follow-up)","Cross-reference to only one external technical document (Eurocopter SB AS355 62.24 R1)","No defined terms section or interpretation provisions","Background section provides clear rationale for the amendment","Total length: approximately 200 words"],"plain_english_summary":"This CASA Airworthiness Directive mandates inspection and, if needed, replacement of pitch change horn bushes on certain Eurocopter AS355 E/F/F1/F2/N helicopters to prevent bolt failure that could cause loss of rotor control. It applies to part number 350A31-1877-02 without an “X” and with serial numbers below 100-000, and follows Eurocopter Service Bulletin AS355 62.24 R1 with inspection and follow-up deadlines tied to 12 May 1993."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Amendment 1 broadened applicability: it extends the serial‑number range of affected pitch change horns to include all serials up to 100‑000 (previous wording excluded some serials). The required inspections/replacements and the compliance timeframes remain as originally issued, but more helicopters are brought into scope."},"complexity_factors":["Narrow technical scope — specific helicopter models and one part number reduce procedural complexity.","Clear remedial path — reliance on a single manufacturer service bulletin provides prescribed steps.","Short compliance windows (50 and 300 flight hours) create scheduling pressure for operators and maintenance providers.","Part traceability requirement — operators must check part numbers, serials and markings (presence/absence of ‘X’).","Possible operational costs — parts availability, labour and aircraft downtime impose practical burdens.","Regulatory cross-reference — mentions DGAC AD and effective dates which must be reconciled in record‑keeping."],"plain_english_summary":"This airworthiness directive requires operators of Eurocopter AS355 E/F/F1/F2/N helicopters fitted with pitch change horns P/N 350A31-1877-02 (serials below 100‑000 and not marked ‘X’) to follow Eurocopter Service Bulletin AS355 62.24 R1: inspect and, if necessary, replace main rotor pitch change horn bushes within prescribed flight‑hour limits to avoid possible bolt failure. Affected parties (aircraft owners/operators and maintenance providers) pay for inspections, any replacements and associated downtime; the regulator sets the deadlines and enforces compliance."}},"importantCases":[],"_links":{"self":"/api/acts/ad-as-355-41-amdt-1-main-rotor-pitch-change-horn-bushes","history":"/api/acts/ad-as-355-41-amdt-1-main-rotor-pitch-change-horn-bushes/history","analysis":"/api/acts/ad-as-355-41-amdt-1-main-rotor-pitch-change-horn-bushes/analysis","conflicts":"/api/acts/ad-as-355-41-amdt-1-main-rotor-pitch-change-horn-bushes/conflicts","importantCases":"/api/acts/ad-as-355-41-amdt-1-main-rotor-pitch-change-horn-bushes/important-cases","documents":"/api/acts/ad-as-355-41-amdt-1-main-rotor-pitch-change-horn-bushes/documents"}}