{"id":"F2007L01504","name":"AD/AS 355/96 - Main & Tail Rotors Servo Controls","slug":"ad-as-355-96-main-tail-rotors-servo-controls","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":65954,"registerId":"commonwealth-F2007L01504-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 355/96 | Main & Tail Rotors Servo Controls | 7/2007 TX |\n| ------------ | --------------------------------- | --------- |\n\n| Applicability: | EUROCOPTER helicopters models - AS 355 E, F, F1, F2 and N, equipped with GOODRICH main rotor servo-controls and tail rotor servo-controls with no letter “C” marked in the inspection box of the servo-control identification plate, and with the following Part Numbers (P/N) and Serial Numbers (S/N):- Main rotor servo-controlsP/N SC5083 with S/N 270M, 272M, 409M, 423M, 452M or 1573P/N SC5083-1 with S/N from 2902 to 2921, inclusiveP/N SC5084 with S/N 30, 84, 104, 186, 438, 575 or 695P/N SC5084-1 with S/N from 1462 to 1481, inclusive.And- Tail rotor servo-controls:P/N SC5072 with serial number 222M, 306M or 309.                                                                                                                                                                                                                                  |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Verify the P/N and S/N of the main rotor and tail rotor servo-controls in accordance with paragraph 1.E.2. of EUROCOPTER Alert Service Bulletin (ASB) No. 01.00.53 Revision 1 or later NAA approved revision.Instead of inspecting the rotorcraft, a review of the helicopter maintenance records along with any other applicable data (rotorcraft logbook, Components list, etc...) is acceptable if each P/N and S/N can be positively determined from that review.2. When a servo-control whose P/N and S/N are listed in the applicability section of this AD, is identified:a. Check thoroughly that no “hard point” exists in the flight controls.b. If any “hard point” is detected in the flight controls, replace the defective servo-control(s) as instructed in paragraph 2.B. of EUROCOPTER ASBNo. 01.00.53 Revision 1 or later NAA approved revision. |\n\n|             | c. Replace all servo-controls that are identified in the applicability section of this AD, as instructed in paragraph 2.B. of EUROCOPTER ASBNo. 01.00.53 Revision 1 or later NAA approved revision.3. Do not install rotors servocontrols whose P/N and S/N are listed in the applicability section of this AD, on any EUROCOPTER AS 355 helicopter unless they have been previously returned to conformity by the equipment manufacturer as indicated in paragraph 2. of EUROCOPTER ASB No. 01.00.53 Revision 1 or later NAA approved revision.Note: EASA Emergency AD 2007-0141-E dated 21May 2007 refers.                                                                                             |\n| ----------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Compliance: | 1. Before further flight, after the effective date of this AD.2. a. During each pre-flight test (see Rotorcraft Flight Manual section 4) and until accomplishment of requirement 2c of this AD is completed.b. Before further flight, after the effective date of this AD.c. Within the next 50 Flight Hours or 4 months after the effective date of this AD, whichever occurs first.3. After the effective date of this AD.                                                                                                                                                                                                                                                                             |\n|             | This Airworthiness Directive becomes effective on 25 May 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |\n| Background: | An internal review revealed that some main and tail rotor servo-controls do not conform to the approved design. This results in a greater play in the input lever bearing which could lead to off-centered lever/distributor slide valve. If not corrected, this condition could jam the distributor slide valve in its sleeve contributing to reduced controllability of the rotors. Such a jamming would be detected during the pre-flight hydraulic check by a “hard point” in the flight controls. This Airworthiness Directive requires identification of the affected main and tail rotor servo-controls and mandates additional attention during the pre flight check and subsequent replacement. |\n\n![](image.001.png)  \nCharles Lenarcic  \nDelegate of the Civil Aviation Safety Authority\n\n22 May 2007","sortOrder":0},{"sectionNumber":"AD/AS 355/96","sectionType":"part","heading":"AD/AS 355/96","content":"## AD/AS 355/96","sortOrder":1},{"sectionNumber":"Main & Tail Rotors Servo Controls","sectionType":"part","heading":"Main & Tail Rotors Servo Controls","content":"## Main & Tail Rotors Servo Controls","sortOrder":2},{"sectionNumber":"7/2007 TX","sectionType":"part","heading":"7/2007 TX","content":"## 7/2007 TX","sortOrder":3}],"analysis":{"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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive's scope is limited to the specific Goodrich servo‑control part and serial numbers listed in the Applicability and requires inspection, detection of any ‘‘hard point’’, replacement of defective or listed units, and prohibition on reinstalling listed units unless returned to conformity by the manufacturer (Requirement; Applicability). There is no text in the instrument indicating a change or expansion of that original scope."},"complexity_factors":["Detailed identification by specific part numbers and serial numbers limits applicability to particular units (Applicability).","Allows record review instead of physical inspection if P/N and S/N can be positively determined, adding a procedural compliance option (Requirement para 1).","Multiple, different compliance deadlines: immediate (before further flight), each pre‑flight until replacement, and within 50 flight hours or 4 months for full replacement (Compliance).","Direct replacement mandate for any defective or listed servo‑controls and a blanket replacement of listed units (Requirement para 2.b–2.c).","Prohibition on installing listed servo‑controls unless returned to conformity by the manufacturer shifts responsibility for restoring conformity to the equipment maker (Requirement para 3).","References to EUROCOPTER Alert Service Bulletin No. 01.00.53 Revision 1 or later NAA‑approved revision create dependency on an external manufacturer document and national aviation authority approval (Requirement).","Detection relies on operator pre‑flight hydraulic checks detecting a ‘hard point’ (Background; Requirement 2.a), which places some burden on pilot/maintenance routines.","Operational impacts include parts removal/return, downtime and replacement costs borne by operators during the compliance windows (inferred from Requirement and Compliance).","Cross‑reference to EASA Emergency AD indicates alignment with an external safety directive and potential for coordinated international compliance (Note/EASA reference)."],"plain_english_summary":"This Airworthiness Directive requires operators to identify specific Goodrich main‑ and tail‑rotor servo‑controls (by part and serial number), carry out additional pre‑flight hydraulic checks for any “hard point”, and replace any defective or listed units. It also prohibits installing the listed servo‑controls unless the equipment manufacturer has returned them to conformity. It applies to Eurocopter AS 355 E/F/F1/F2/N helicopters fitted with the listed servo‑controls and addresses a risk that increased bearing play could jam a distributor slide valve (Background)."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This appears to be a standard emergency Airworthiness Directive addressing a specific safety-critical manufacturing defect. The scope remains tightly focused on identifying and replacing defective servo-controls in the specified helicopter models. There is no evidence of scope creep beyond the original safety purpose."},"complexity_factors":["Multiple specific part numbers (P/N) and serial number ranges (S/N) to cross-reference — 6 distinct P/Ns with specific S/N lists or ranges","Conditional logic: different actions required depending on whether affected parts are found (inspection vs. replacement vs. pre-flight checks)","Alternative compliance method allowed (maintenance records review instead of physical inspection) with conditions","Nested timing requirements: immediate, recurring (each pre-flight), and deadline-based (50 hours/4 months)","Reference to external technical document (Eurocopter Alert Service Bulletin No. 01.00.53 Revision 1) for detailed procedures","Cross-reference to European regulator (EASA Emergency AD 2007-0141-E)","Technical aviation terminology requiring domain knowledge (servo-controls, hard points, distributor slide valve, input lever bearing)"],"plain_english_summary":"This CASA Airworthiness Directive orders owners/operators of Eurocopter AS355 (E/F/F1/F2/N) helicopters to inspect main and tail rotor Goodrich servo-controls (identified by listed P/Ns/S/Ns and lacking a “C” mark). A bearing defect can cause control-valve jamming and in-flight “hard points,” risking loss of control.\n\nOperators must verify parts before flight, perform pre-flight hard-point checks until replacement, and replace affected units within 50 flight hours or 4 months; installation of unmodified units is prohibited."}},"importantCases":[],"_links":{"self":"/api/acts/ad-as-355-96-main-tail-rotors-servo-controls","history":"/api/acts/ad-as-355-96-main-tail-rotors-servo-controls/history","analysis":"/api/acts/ad-as-355-96-main-tail-rotors-servo-controls/analysis","conflicts":"/api/acts/ad-as-355-96-main-tail-rotors-servo-controls/conflicts","importantCases":"/api/acts/ad-as-355-96-main-tail-rotors-servo-controls/important-cases","documents":"/api/acts/ad-as-355-96-main-tail-rotors-servo-controls/documents"}}