{"id":"F2006B09356","name":"AD/ECUREUIL/50 Amdt 1 - Main Rotor Pitch Change Horn Bushes","slug":"ad-ecureuil-50-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":53605,"registerId":"commonwealth-F2006B09356-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/ECUREUIL/50 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 350 (Ecureuil) Series Helicopters\n\nAD/ECUREUIL/50\n\nAmdt 1\n\n  \nMain Rotor Pitch Change Horn Bushes 7/93\n\nDM\n\nApplicability: Models B, D, B1, B2, and BA 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 350 62.21 R1.\n\nNote: DGAC AD 92-179-064(B) 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.\n\nThe 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":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"Amendment 1 broadened the AD's applicability by including all pitch change horn serial numbers up to 100-000 (previously a narrower set). This increases the population of affected parts/aircraft required to comply (see Background and Applicability)."},"complexity_factors":["Technical specificity: targets a particular part (pitch change horn bushes) and defect (incorrect taper).","Serial-number-based applicability: applicability limited to parts without an “X” and with serial numbers below 100-000 (expanded by Amendment 1).","Cross-reference to manufacturer material: compliance requires following Eurocopter SB 350 62.21 R1 rather than full text in the AD.","Time-limited compliance windows: two different service-hour deadlines (50 hours and, if required, 300 hours).","Operational burden: inspections/repairs must be scheduled into service programs and funded by owners/operators.","Regulatory layering: AD references foreign authority (DGAC) and a service bulletin, increasing sources to consult."],"plain_english_summary":"This Airworthiness Directive requires operators of Eurocopter AS350 (Ecureuil) helicopters to inspect and, if necessary, correct main-rotor pitch-change-horn bushes in accordance with Eurocopter Service Bulletin 350 62.21 R1. It sets mandatory compliance windows (initial action within 50 flight hours, and if prompted a further action within 300 hours).\n\nIt affects aircraft owners/operators and maintenance organisations, who must carry out and pay for the inspections/repairs; CASA enforces adherence. The directive responds to incorrectly tapered bushes that could cause failure of the pitch-change-horn-to-rod connecting bolt."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":true,"description":"The original directive (issued November 1992) had narrower applicability criteria. Amendment 1 explicitly expands the scope to include 'all pitch change horn serial numbers to 100-000' — broadening coverage to capture additional at-risk components that the initial issue may have excluded."},"complexity_factors":["Single, narrow technical scope focused on one specific helicopter part","Only 4 defined applicability criteria (model, part number, marking, serial number)","Simple two-stage compliance timeline (50 hours / 300 hours)","No nested exceptions or conditional logic — requirements are straightforward","Short document (approximately 200 words) with clear structure","Single external reference to manufacturer service bulletin (SB 350 62.21 R1)"],"plain_english_summary":"This CASA Airworthiness Directive mandates inspection and possible replacement of pitch change horn bushes on certain Eurocopter AS350 (Ecureuil/Squirrel) helicopters after some bushes were made with an incorrect taper that can allow the connecting bolt to fail and cause loss of rotor pitch control. It applies to P/N 350A31‑1877‑02 without an “X” and serial numbers below 100‑000. Operators must follow Eurocopter Service Bulletin 350‑62.21 R1, with an initial check within 50 flight hours and follow‑up actions within 300."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ecureuil-50-amdt-1-main-rotor-pitch-change-horn-bushes","history":"/api/acts/ad-ecureuil-50-amdt-1-main-rotor-pitch-change-horn-bushes/history","analysis":"/api/acts/ad-ecureuil-50-amdt-1-main-rotor-pitch-change-horn-bushes/analysis","conflicts":"/api/acts/ad-ecureuil-50-amdt-1-main-rotor-pitch-change-horn-bushes/conflicts","importantCases":"/api/acts/ad-ecureuil-50-amdt-1-main-rotor-pitch-change-horn-bushes/important-cases","documents":"/api/acts/ad-ecureuil-50-amdt-1-main-rotor-pitch-change-horn-bushes/documents"}}