{"id":"F2006B02514","name":"AD/AS 355/64 Amdt 1 - Main Servocontrol Rods","slug":"ad-as-355-64-amdt-1-main-servocontrol-rods","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41770,"registerId":"commonwealth-F2006B02514-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AS 355/64 Amdt 1 - Main Servocontrol Rods","content":"![](image.001.png)\n\n![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/AS 355/64 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 355/64\n\nAmdt 1\n\n  \n\nMain Servocontrol Rods 7/2003 TX\n\nApplicability: All AS 355 helicopters, versions E, F, F1, F2 and N, fitted with main and tail servocontrols listed in Table 1 and Table 2 of this Directive.\n\nTable 1 \\- TRW-SAMM Main Servocontrols part number (P/N) SC 5083 and SC 5084 with part numbers without the suffix “V” with the following serial numbers:\n\n| Part Number | Serial Number          |\n| ----------- | ---------------------- |\n| SC 5083     | 1500 to 1515 inclusive |\n| SC 5084     | 722 to 726 inclusive.  |\n\nTable 2 - Main and tail servocontrols, P/N SC5081-1, SC5082-1, SC5083, SC5084, SC5071-1 and SC5072, with part numbers without suffix \"V\", with the following serial numbers:\n\n| SC5081-1 | 78, 89, 227, 240, 315, 362, 427, 451,   |\n| -------- | --------------------------------------- |\n|          | 452, 492, 497, 498, 506, 512,532, 550,  |\n|          | 556, 561.                               |\n| SC5082-1 | 045, 180, 194, 197, 254, 264.           |\n| SC5083   | 01, 03, 05, 082, 17, 21, 40, 43M, 65M,  |\n|          | 77, 87, 103M, 106M, 107, 109, 128,      |\n|          | 129, 138, 139, 144, 148, 152, 206, 207, |\n|          | 218, 221, 226, 235, 239, 240, 241, 243, |\n|          | 254, 256, 269, 286, 287, 290, 291, 302, |\n|          | 312, 321,325, 327, 330, 331, 334, 338,  |\n|          | 339, 347M, 356M, 365, 371, 372,         |\n|          | 378M, 380M, 389, 412M, 418, 423,        |\n|          | 428, 439, 484M, 503, 505, 525, 526,     |\n|          | 528, 529, 573M, 587, 594M, 598, 612,    |\n|          | 622, 1150 to 1155, 1157, 1159 to 1169,  |\n|          | 1180 to 1199, 1207, 1208, 1210 to 1259, |\n|          | 1269, 1291 to 1499.                     |\n\nTable 2 continued\n\n| SC5084   | 013, 025, 31, 75, 087, 87, 101M, 102,105, 108, 136, 160, 162, 165M, 203,205, 205M, 209, 220, 225, 232M,239M, 267M, 271, 288M, 292, 300,320, 364M, 458, 612, 627, 630, 632 to634, 636 to 652, 654, 656 to 660, 682 to721, 727 to 731, 733 to 756. |\n| -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| SC5071-1 | 343, 389.                                                                                                                                                                                                                                        |\n| SC5072   | 003, 35, 108, 197, 216M, 253M, 339M,347M, 432M, 700 to 724, 726 to 744,763 to 768, 783 to 789, 820 to 883.                                                                                                                                       |\n\nNote 1: Servocontrols that have been checked or reconditioned by TRW-SAMM and are identified by a letter “V” engraved to the right of the part number on the identification plate.\n\nRequirement: 1. Unless previously accomplished check whether any of the servocontrols listed in Table 1 and Table 2 of this Directive are installed on the aeroplane.\n\n    2. Unless previously accomplished replace any servocontrols listed in Table 1 with servocontrols not listed in Table 1 or Table 2.\n\n    3. Replace any servocontrols listed in Table 2 with servocontrols not listed in Table 1 or Table 2.\n\n    4. Do not install any servocontrols listed in Table 1 or Table 2 of this Directive.\n\nNote 2: DGAC AD 2003-100(A) refers.\n\nCompliance: 1. Before further flight.\n\n    2. Before further flight.\n\n    3. Within 550 flight hours or 24 months, whichever occurs first, after the effective date of this Directive.\n    4. From the effective date of this directive.\n\nThis Amendment becomes effective on 9 May 2003.\n\nBackground: This Directive was prompted by advice that a manufacturing defect has been detected in a batch of rods of the main servocontrol. Failure of the rod will lead to loss of control of the helicopter. This amendment is prompted by additional defects being discovered in servocontrols with additional part numbers and serial numbers.\n\nThis original issue of this Directive became effective 3 December 2001.\n\n![](image.002.png)  \n\nJim Coyne\n\nDelegate of the Civil Aviation Safety Authority 6 May 2003\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 9 May 2003.","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":6,"scope_assessment":{"changed":true,"description":"The amendment expanded the scope of the original Directive by adding additional servocontrol part numbers and many more serial numbers after more defects were discovered. The original AD (effective 3 December 2001) addressed a smaller set of parts/serials; this Amendment 1 increases the population of affected components and tightens the removal/install prohibition (see Background; Tables 1 and 2)."},"complexity_factors":["Two tables listing multiple distinct part numbers and many specific serial numbers and serial ranges (Table 1 and Table 2).","Conditional deadlines with different urgency levels: 'before further flight' for Table 1 items and immediate checks, but up to 550 flight hours or 24 months for Table 2 items (Compliance 1–3).","Exception based on an engraved suffix 'V' on the part identification plate (Note 1) — identification depends on physical marking.","Requirement that replacements must be servocontrols not listed in either table (Requirement 2–3) — a negative specification that requires cross‑checking inventories.","Cross‑reference to a foreign AD (DGAC AD 2003‑100(A)) (Note 2) and revocation of an earlier AD (introductory paragraph) introduces external document dependency.","Operational complexity from many small, non‑sequential serial numbers and mixed formats (e.g. numbers with 'M' suffixes and ranges), increasing risk of human error during inspection.","Multiple affected aircraft variants (AS 355 E/F/F1/F2/N) creating varied fleet impacts (Applicability)."],"plain_english_summary":"**What this directive does (mechanically)**\n\n- This is an Airworthiness Directive (AD) issued by the Civil Aviation Safety Authority (CASA) delegate that replaces an earlier AD. It requires operators to identify and remove certain servo‑control rods (the part that links pilot controls to rotor control surfaces) on Eurocopter AS 355 series helicopters and to prevent those parts from being reinstalled. (See Applicability; Requirement; Compliance.)\n\n**Which aircraft and parts are affected**\n\n- Affects Eurocopter AS 355 versions E, F, F1, F2 and N when fitted with specific TRW‑SAMM servocontrol part numbers and serial numbers listed in Table 1 and Table 2 of the Directive (see Note 1 about a \"V\" suffix). (Applicability; Table 1; Table 2; Note 1.)\n\n**What operators must do**\n\n- Check whether any servocontrols from Table 1 or Table 2 are installed. (Requirement 1; Compliance 1.)\n- If a servocontrol is listed in Table 1, remove and replace it with a servocontrol that is not listed in either Table 1 or Table 2 before the aircraft’s next flight. (Requirement 2; Compliance 2.)\n- If a servocontrol is listed in Table 2, replace it with a servocontrol not listed in Table 1 or Table 2 within 550 flight hours or 24 months after the AD’s effective date, whichever comes first. (Requirement 3; Compliance 3.)\n- Do not install any servocontrol listed in Table 1 or Table 2 after the AD’s effective date. (Requirement 4; Compliance 4.)\n\n**Why the rule was made (stated reason)**\n\n- CASA says a manufacturing defect was found in a batch of main servocontrol rods. The defect can cause rod failure and result in loss of helicopter control. The amendment expands the list of affected part numbers and serial numbers after additional defects were discovered. (Background.)\n\n**Practical effects, incentives and tradeoffs**\n\n- Who pays: Owners/operators pay for inspections, parts removal, purchase of replacement servocontrols, and associated labour and aircraft downtime. (Requirement & Compliance.)\n- Who decides: The operator (or its maintenance organisation) must do the inspection and arrange replacement; CASA enforces compliance through its regulatory powers under CASR subregulation 39.1(1) (this AD). (Introductory text; Requirement.)\n- Behaviour changes required: Operators must inspect, remove listed parts promptly (some before next flight), not reinstall listed parts, and schedule replacement of Table 2 items within the stated time limit. (Requirement 1–4; Compliance 1–4.)\n- Costs and opportunity costs: Immediate grounding for aircraft with Table 1 parts imposes urgent costs (parts, labour, lost flight time). Replacing Table 2 parts within 550 hours/24 months spreads cost but still requires planned expenditure and potential inventory churn. There may be short‑term supply pressure for acceptable replacement parts. (Requirement & Compliance.)\n- Compliance burden: Identification depends on part numbers and specific serial numbers (many individual numbers and ranges) and on the presence/absence of a \"V\" marking (Note 1). That creates administrative and technical inspection work for maintenance organisations and increases the chance of identification errors. (Table 1; Table 2; Note 1.)\n- Effects on markets and competition: Demand shifts to servocontrols not listed in Tables 1–2 (including reconditioned parts marked with a \"V\", which are noted as having been checked/reconditioned and are therefore excluded from the lists). That benefits suppliers of compliant parts and reconditioned units, and reduces demand for the listed items. Price and availability of acceptable replacements may rise while listed parts become unusable for installation. (Table 1; Table 2; Note 1.)\n- Implementation risks and substitution effects: The AD permits using servocontrols that are not on the lists; operators may choose new OEM parts, reconditioned units with a \"V\" marking, or aftermarket alternatives if certified. Mis‑identification of serial numbers or failure to notice the \"V\" marking could lead to non‑compliance or unnecessary removals. (Table 1; Table 2; Note 1.)\n- Enforcement and recordkeeping: The AD imposes clear timing (before next flight, within 550 hours/24 months) that will be checked by regulators and during maintenance audits; operators must record inspections and replacements to demonstrate compliance. (Compliance 1–3.)\n\n**References inside the Directive**\n\n- The AD lists exact part numbers and detailed serial numbers (Table 1 and Table 2), notes that items marked with a \"V\" have been reconditioned and are treated differently (Note 1) and cross‑references a French DGAC AD (Note 2). (Table 1; Table 2; Note 1; Note 2; Background.)\n\n**Net mechanical effect**\n\n- The AD removes from service a defined set of servocontrol rods and prohibits their future installation, requiring operators to replace them with units not listed in the Directive within specified timeframes. This enforces a switch away from parts identified as at risk of rod failure, at the direct expense and effort of the operators and their maintenance providers. (Requirement 1–4; Compliance 1–4; Background.)"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":true,"description":"The original AD (effective December 2001) covered a specific batch of defective servocontrol rods. This Amendment 1 significantly expands the scope to cover additional part numbers and serial numbers after 'additional defects were discovered.' The applicability section grew from the original Table 1 to include Table 2 with substantially more affected serial numbers. The compliance structure also became more complex, adding tiered deadlines rather than a single immediate action."},"complexity_factors":["Extensive tabular data: Two detailed tables listing specific part numbers and serial numbers (over 200 individual serial numbers across multiple part number ranges)","Technical aviation terminology: References to specific aircraft components (servocontrols, part number suffixes, identification plates) requiring domain knowledge","Layered applicability: Multiple helicopter versions (E, F, F1, F2, N) plus conditional applicability based on part numbers with/without 'V' suffix","Staged compliance requirements: Four separate requirements with different deadlines (immediate vs. 550 hours/24 months vs. ongoing prohibition)","Cross-reference to foreign regulation: Note 2 references French aviation authority directive DGAC AD 2003-100(A)","Amendment structure: Revokes previous AD and reissues with expanded scope, requiring understanding of amendment relationship to original"],"plain_english_summary":"This AD mandates inspection and replacement of certain TRW‑SAMM main servocontrol rods on Eurocopter AS355 (E, F, F1, F2, N) helicopters because rod failure can cause loss of control. Parts from the highest‑risk batch must be removed before next flight; remaining affected parts must be replaced within 550 flight hours or 24 months, and the listed defective parts must never be reinstalled. The 2003 update expands the recall to additional defective rods found since 2001."}},"importantCases":[],"_links":{"self":"/api/acts/ad-as-355-64-amdt-1-main-servocontrol-rods","history":"/api/acts/ad-as-355-64-amdt-1-main-servocontrol-rods/history","analysis":"/api/acts/ad-as-355-64-amdt-1-main-servocontrol-rods/analysis","conflicts":"/api/acts/ad-as-355-64-amdt-1-main-servocontrol-rods/conflicts","importantCases":"/api/acts/ad-as-355-64-amdt-1-main-servocontrol-rods/important-cases","documents":"/api/acts/ad-as-355-64-amdt-1-main-servocontrol-rods/documents"}}