{"id":"F2007L01398","name":"AD/AS 355/93 - Main and Tail Rotors - Servo Controls","slug":"ad-as-355-93-main-and-tail-rotors-servo-controls","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":65750,"registerId":"commonwealth-F2007L01398-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Eurocopter AS 355 (Twin Ecureuil) Series","sectionType":"division","heading":"Eurocopter AS 355 (Twin Ecureuil) Series Helicopters","content":"### Eurocopter AS 355 (Twin Ecureuil) Series Helicopters\n\n| AD/AS 355/93 | Main and Tail Rotors - Servo Controls | 6/2007 |\n| ------------ | ------------------------------------- | ------ |\n\n| Applicability: | Eurocopter AS 355 F, F1, F2 and N helicopters that are fitted with GOODRICH main and tail rotor servo-controls without the letter “R” marked in the inspection box of the servo-control identification plate, and whose Part Number (P/N) and Serial Number (S/N) are listed in paragraph 1.A of Eurocopter Alert Service Bulletin (ASB) AS 355 No. 67.00.28.                                                                                                                                                                                                                                                                                                               |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Check for identification of the P/N and S/N of the servo-controls installed on helicopters and on the shelves listed in paragraph 1.A of Eurocopter ASB AS 332 No. 67.00.37 or later approved revisions.2. Remove from service those servo-controls identified as having P/N and S/N listed in paragraph 1.A of Eurocopter ASB AS 355 No. 67.00.28 or later approved revisions.3. Do not install servo-controls with P/N and S/N as listed in paragraph 1.A Eurocopter ASB AS 355 No. 67.00.28 unless they have returned to conformity as detailed in Eurocopter ASB AS 355 No. 67.00.28 or later approved revisions.Note: EASA AD 2007-0099 dated 11 April 2007 refers. |\n| Compliance:    | 1. Within 2 months from the effective date of this AD.2. Within 2 years from the effective date of this AD.3. From the effective date of this AD.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |\n|                | This Airworthiness Directive becomes effective on 7 June 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |\n\n| Background: | This AD is in response to a manufacturing non-conformity found on one batch of servo-control cap P/N 800137. A defective servo-control may not stop the rotation of the distributor sleeve which could cause untimely movements of the servo-controls which are used on the main and anti-torque rotors. This can lead to loss of control of the helicopter. |\n| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n\n![](image.001.png)  \nDavid Punshon  \nDelegate of the Civil Aviation Safety Authority\n\n26 April 2007","sortOrder":0},{"sectionNumber":"AD/AS 355/93","sectionType":"part","heading":"AD/AS 355/93","content":"## AD/AS 355/93","sortOrder":1},{"sectionNumber":"Main and Tail Rotors - Servo Controls","sectionType":"part","heading":"Main and Tail Rotors - Servo Controls","content":"## Main and Tail Rotors - Servo Controls","sortOrder":2},{"sectionNumber":"6/2007","sectionType":"part","heading":"6/2007","content":"## 6/2007","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD implements a safety measure limited to the affected batch and listed P/N/S/N: identify affected servo-controls, remove them from service, and prohibit installation until returned to conformity. It does not expand applicability beyond the parts and serial numbers specified, though it relies on approved future ASB revisions for definitive lists and conformity instructions."},"complexity_factors":["Narrow applicability tied to specific airframe models and specific P/N and S/N listed in paragraph 1.A of ASB AS 355 No. 67.00.28 (Applicability).","Operational steps are straightforward but require inventory checks of installed units and spares/shelves (Requirement 1; Compliance 1).","Multiple compliance timeframes: immediate prohibition on installation, identification within 2 months, removal within 2 years (Compliance 1–3) create staged operational planning.","Dependence on an external document (Eurocopter ASB AS 355 No. 67.00.28) and its later approved revisions for the definitive list and conformity process increases procedural dependence on manufacturer/ASB updates (Requirement note).","Removal-from-service mandate imposes direct replacement/maintenance costs and potential aircraft downtime borne by operators (Requirement 2).","Safety risk prompting the AD is specific: a manufacturing non‑conformity in servo-control cap P/N 800137 that could allow untimely distributor sleeve rotation and unintended control movement (Background).","Reference to EASA AD 2007-0099 indicates harmonisation with overseas regulator action, adding cross-jurisdictional conformity expectations (Note)."],"plain_english_summary":"This Airworthiness Directive requires operators of Eurocopter AS 355 F/F1/F2/N helicopters fitted with certain GOODRICH main and tail rotor servo-controls (P/N and S/N listed in paragraph 1.A of Eurocopter ASB AS 355 No. 67.00.28) to identify those units, remove listed units from service, and not install listed units unless returned to conformity (Requirement 1–3; Compliance 1–3). Operators bear the cost and logistics of inspection, removal and replacement; CASA enforces the rule. The AD responds to a manufacturing non‑conformity that may allow unintended servo movement and risk loss of control (Background). Effective 7 June 2007."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standard, narrow Airworthiness Directive addressing a specific manufacturing defect in a specific component. The scope remains tightly focused on the identified safety issue without expansion into broader operational or regulatory matters."},"complexity_factors":["Short, single-purpose directive with only 3 requirements","No defined terms section — relies entirely on external references to Eurocopter service bulletins (ASB AS 355 No. 67.00.28 and ASB AS 332 No. 67.00.37)","Simple conditional logic: only applies to helicopters with specific part/serial numbers AND lacking the 'R' inspection mark","No nested exceptions or complex cross-references within the document itself","External dependency on manufacturer service bulletins for actual part identification (operators must obtain and read separate technical documents)"],"plain_english_summary":"This AD orders operators and maintenance personnel of Eurocopter AS 355 F/F1/F2/N helicopters to inspect, remove and replace specific Goodrich main- and tail-rotor servo-controls identified in the manufacturer’s bulletin. A manufacturing defect in some caps can allow uncontrolled distributor sleeve rotation, risking sudden flight‑control movements and loss of control. Inspect installed and spare units within 2 months, remove faulty units within 2 years, and do not install unrepaired defective servo-controls."}},"importantCases":[],"_links":{"self":"/api/acts/ad-as-355-93-main-and-tail-rotors-servo-controls","history":"/api/acts/ad-as-355-93-main-and-tail-rotors-servo-controls/history","analysis":"/api/acts/ad-as-355-93-main-and-tail-rotors-servo-controls/analysis","conflicts":"/api/acts/ad-as-355-93-main-and-tail-rotors-servo-controls/conflicts","importantCases":"/api/acts/ad-as-355-93-main-and-tail-rotors-servo-controls/important-cases","documents":"/api/acts/ad-as-355-93-main-and-tail-rotors-servo-controls/documents"}}