{"id":"F2009L01000","name":"AD/ECUREUIL/71 Amdt 4 - Tail Rotor Blade Trailing Edge","slug":"ad-ecureuil-71-amdt-4-tail-rotor-blade-trailing-edge","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":78634,"registerId":"commonwealth-F2009L01000-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Eurocopter AS 350 (Ecureuil) Series Heli","sectionType":"division","heading":"Eurocopter AS 350 (Ecureuil) Series Helicopters","content":"### Eurocopter AS 350 (Ecureuil) Series Helicopters\n\n| AD/ECUREUIL/71 Amdt 4 | Tail Rotor Blade Trailing Edge | 4/2009 |\n| --------------------- | ------------------------------ | ------ |\n\n| Applicability: | Model AS 350 helicopters, versions B, BA, BB, B1, B2, B3, and D, equipped with a tail rotor blade part number listed below:355A12-0031-01, -02, -03, -04, -05, -06, -07, -08, -09, -11, -12, -13, -14.355A12-0040-00, -01, -02, -03, -04, -05, -07, -08.355A12-0050-00, -01, -02, -03, -04, -05.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Visually inspect the tail rotor blades in accordance with paragraph 2.B.1. of Eurocopter AS 350 Alert Service Bulletin (ASB) No. 05.00.40 Revision 2, or later EASA approved revision.If a crack is detected during any inspection, before further flight, accomplish the instructions specified in paragraph 2.B.2. of ASB No. 05.00.40 Revision 2, or later EASA approved revision.2. Accomplish the instructions of Repair Sheet FR CN 376 or FR CN 453 on tail rotor blades part number 355A12-0050-00, -01, -02, -03, -04, -05 with serial numbers listed in paragraph 2.B.2.a. of ASB No. 05.00.40 Revision 3, or later EASA approved revision, and on blades with serial numbers below 8419; for which the annotation “repaired as per Work Card 64.10.00.872” or “repaired as per Work Card 64.10.20.712” is recorded on the log card.3. No person shall install tail rotor blades with a part number that is listed in the applicability section of this Directive on any Model AS 350 helicopter, unless they have been inspected and repaired, as necessary, in accordance with paragraph 2.B.1 of ASB No. 05.00.40 Revision 3, or later EASA approved revision.Previous accomplishment of FR CN 376 on tail rotor blades in accordance with ASB No. 05.00.40 Revision 2 is considered compliant with Requirements 2 and 3 of this Directive.Note: EASA AD 2007-0138R2 refers. |\n\n| Compliance: | 1. At each check after the last flight of the day (ALF check), and not exceeding 10 flight hours between two successive checks.2. Remains unchanged as: No later than 31 March 2009, unless already accomplished.3. As of the effective date of this Directive.The compliance times remain unchanged by this issue of the Directive.This Directive shall be entered on the Maintenance Release as maintenance required. The required visual inspection may be performed and certified by a Pilot in Command who has been trained to do the inspection by an appropriately qualified person. In this case, a copy of the Requirement document and this Directive is to be carried in the aircraft.                                                                                                                                                                                                                          |\n| ----------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n|             | This Amendment becomes effective on 9 April 2009.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |\n| Background: | The DGAC received a report of separation of a tail rotor blade trailing edge section due to crack growth in the blade skin. The unbalance caused by the loss of a blade section can cause tail rotor gearbox separation.Amendment 1 introduced certain actions to rotors installed on version B3 helicopters that are fitted with a 30mm trailing edge tab.Amendment 2 introduced requirements to alleviate maintenance for tail rotor blades repaired as per Repair Sheet (FR) CN 376; as specified in the latest revision of the Requirement document.Amendment 3 added a new Repair Sheet FR CN 453, and extended the repair accomplishment timescale accordingly; as specified in the latest revision of the Requirement document.Amendment 4 is issued in response to a revision of the related EASA AD, which introduces a correction to the Requirement 1 compliance; with no change to the technical requirements. |\n\n![](image.001.png)  \nDavid Punshon  \nDelegate of the Civil Aviation Safety Authority\n\n6 February 2009","sortOrder":0},{"sectionNumber":"AD/ECUREUIL/71 Amdt 4","sectionType":"part","heading":"AD/ECUREUIL/71 Amdt 4","content":"## AD/ECUREUIL/71 Amdt 4","sortOrder":1},{"sectionNumber":"Tail Rotor Blade Trailing Edge","sectionType":"part","heading":"Tail Rotor Blade Trailing Edge","content":"## Tail Rotor Blade Trailing Edge","sortOrder":2},{"sectionNumber":"4/2009","sectionType":"part","heading":"4/2009","content":"## 4/2009","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This is Amendment 4 of an existing Airworthiness Directive. The Background section explicitly states that Amendment 4 introduces 'no change to the technical requirements' — it only corrects the compliance timing for Requirement 1 in response to an EASA update. The scope remains focused on tail rotor blade safety for the AS 350 series, consistent with the original AD intent."},"complexity_factors":["Multiple amendment history (Amendments 1-4) with cross-references to previous changes","Extensive part number lists (13 variants of one part number, 8 of another, 6 of a third)","Multiple compliance deadlines with different triggers (ALF checks, calendar date, effective date)","External document dependencies: references to Eurocopter Alert Service Bulletin 05.00.40 (multiple revisions), Repair Sheets FR CN 376 and FR CN 453, and EASA AD 2007-0138R2","Conditional logic: different requirements apply based on blade part numbers, serial numbers, repair history, and previous compliance","Nested exceptions: previous accomplishment of FR CN 376 under Revision 2 counts as compliant with Requirements 2 and 3"],"plain_english_summary":"Owners and operators of certain Eurocopter AS350 helicopters must carry out mandated visual inspections and required repairs on specified tail rotor blades to detect and stop cracking that can shed blade pieces, cause severe vibration, and risk loss of control.  \n\nPilots may perform trained inspections but must carry the directive and record compliance in the aircraft’s maintenance release; uninspected blades cannot be installed."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"Amendment 4 itself does not broaden the technical scope; it corrects the compliance timing in Requirement 1 to match a revision in the related EASA AD and states there is no change to the technical requirements. Earlier amendments (1–3) had expanded or clarified repair requirements and applicability (for example added actions for B3 with a 30 mm tab and introduced FR CN 453), but this Amendment 4 merely adjusts a compliance/timing detail rather than adding new blade types, new technical inspections, or new repair mandates. Therefore this version did not significantly grow the Directive beyond its original safety purpose."},"complexity_factors":["Multiple specific tail rotor blade part numbers listed in applicability (over 30 part-number variants)","Cross-references to an external Alert Service Bulletin (ASB No. 05.00.40) and to specific paragraphs within it (2.B.1 and 2.B.2)","References to multiple revisions of the ASB (Revision 2 and Revision 3) and allowance for later EASA-approved revisions (adds versioning complexity)","Dependence on Repair Sheets FR CN 376 and FR CN 453 and serial-number conditions (serial numbers below 8419 and specific serial lists in ASB)","Conditional compliance rules (e.g., if crack found do X before further flight; prior accomplishment under Rev 2 counts as compliant)","Mixed compliance timing rules (ALF checks not exceeding 10 flight hours; some repair deadlines retained from earlier issues)","Delegation allowing a trained Pilot in Command to perform and certify inspections, with documentary carriage requirement (adds procedural variation)","Cross-reference to an EASA AD (2007-0138R2) and historical amendments that change which blades/repairs are covered"],"plain_english_summary":"**What this instrument does (mechanically)\n\n- Requires visual inspections of specific tail rotor blades on Eurocopter AS 350 (Ecureuil) models B, BA, BB, B1, B2, B3 and D. (Requirement 1)\n- Requires repair work on certain blades with specified part numbers and serial numbers using Repair Sheet FR CN 376 or FR CN 453 where applicable. (Requirement 2)\n- Prohibits installing any of the listed blade part numbers on an AS 350 helicopter unless the blades have been inspected and repaired, if necessary, to the standard in the referenced Alert Service Bulletin (ASB). (Requirement 3)\n- Allows a trained Pilot in Command to perform and certify the required visual inspection under certain conditions; a copy of the Requirement document and this Directive must be carried on the aircraft when this is done. (Compliance)\n\nWho is affected\n\n- Owners, operators and maintainers of Eurocopter AS 350 helicopters (versions B, BA, BB, B1, B2, B3 and D) that use any of the tail rotor blade part numbers listed in the applicability section. The rule applies to maintenance organisations, maintenance personnel, and pilots authorised to carry out the ALF (after last flight) visual checks if they have received the required training. (Applicability; Compliance)\n\nWhy it matters (stated purpose)\n\n- The Directorate General for Civil Aviation (DGAC) reported a tail rotor blade trailing edge section separated due to crack growth in the blade skin. Loss of a trailing edge section creates imbalance that can lead to tail rotor gearbox separation. The Directive intends to detect and repair cracks early to prevent such failures. (Background)\n\nTest of the stated purpose against costs, incentives and trade‑offs\n\n- Costs and who pays: Operators bear the costs — time for the frequent visual checks (see compliance timing below), potential grounding to carry out repairs or replacement, and costs for repair sheets FR CN 376 or FR CN 453 when required. Maintenance entries must be made in the Maintenance Release. (Requirement 2; Compliance)\n- Frequency and operational impact: The Directive requires a visual inspection after each ‘last flight of the day’ (ALF) and no more than every 10 flight hours between checks, which increases daily/short‑flight inspection burden compared to less frequent inspections. This raises recurring labour time and possible aircraft downtime. (Compliance 1)\n- Compliance flexibility: The AD cross‑references Eurocopter ASB No. 05.00.40 revisions (Revision 2 and Revision 3 are mentioned) and allows later EASA‑approved revisions. This gives regulators and operators a mechanism to update inspection/repair detail without changing the Directive. However, it creates dependence on another document (cross‑reference risk). (Requirement 1; Requirement 2)\n- Incentives and behaviour: Operators have an incentive to inspect and repair proactively to avoid unplanned failure and to be eligible to install blades. The prohibition on installing listed blades unless inspected/repaired limits the use of spare blades that haven’t been processed, affecting inventory and logistics. (Requirement 3)\n- Implementation risk and discretion: The Directive permits a Pilot in Command to do and certify the ALF visual check if trained by an appropriately qualified person; this expands who may carry out the check but creates reliance on training quality and on an operator’s internal procedures. The regulator delegates limited discretion to operators in staffing/inspection arrangements. (Compliance)\n- Effects on independent businesses and competition: Maintenance facilities that are certified and experienced with the specified repair sheets will be in greater demand; smaller operators who lack in‑house capability may face higher outlays to contract repairs. However, the Directive does not mandate a specific provider or proprietary service, so competition among capable repair/maintenance providers remains feasible. (Requirement 2)\n- Substitution effects: Operators may choose between increased inspection frequency and pre‑emptive replacement of blades with unaffected part numbers or newer designs, which shifts cost from inspection labour to parts acquisition. (Requirement 3)\n\nKey operational details (how to comply)\n\n- Inspect as per paragraph 2.B.1 of Eurocopter ASB No. 05.00.40 Revision 2 (or later EASA‑approved revision). If a crack is found, follow paragraph 2.B.2 of that ASB before further flight. (Requirement 1)\n- Apply Repair Sheet FR CN 376 or FR CN 453 to blades with specified part numbers and serial numbers as listed in paragraph 2.B.2.a of ASB No. 05.00.40 Revision 3 (or later EASA‑approved revision), and to blades with serial numbers below 8419 that carry the annotation of the specified prior work cards. Previous accomplishment of FR CN 376 under ASB Rev 2 counts as compliant for Requirements 2 and 3. (Requirement 2; Note)\n- Do not fit affected blades to AS 350s unless inspected and repaired per ASB Rev 3 (or later). (Requirement 3)\n- Timetable: ALF checks must be done at each last flight of the day and not exceed 10 flight hours between checks; the repair compliance deadline previously set (no later than 31 March 2009) is retained for blades that required that action; Requirement 3 is effective from the Directive’s effective date. The Directive must be recorded on the aircraft Maintenance Release. (Compliance)\n\nPractical implications for operators\n\n- Increased short‑interval inspection workload (daily or every ≤10 flight hours). (Compliance 1)\n- Potential repair or removal of blades from service, with associated parts and labour costs. (Requirement 2)\n- Inventory management: spare blades of the listed part numbers cannot be installed unless they have been inspected/repaired, which alters spare part usability until action is taken. (Requirement 3)\n- Some inspection work can be done and certified by a trained pilot, reducing reliance on maintenance staff for ALF checks but increasing training and recordkeeping responsibilities. (Compliance)\n\nCross‑references and updates\n\n- The Directive relies on Eurocopter ASB No. 05.00.40 (various revisions) and on Repair Sheets FR CN 376 and FR CN 453. It also refers to EASA AD 2007‑0138R2. That means technical detail and serial‑number lists live in the ASB/repair sheets; operators must consult those documents for the precise inspection and repair steps. (Requirements 1–3; Note)\n\nSources cited in the Directive: Requirement paragraphs 1–3; Compliance section; Background; ASB No. 05.00.40 (Revision 2 and Revision 3); Repair Sheets FR CN 376 and FR CN 453; EASA AD 2007‑0138R2."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-ecureuil-71-amdt-4-tail-rotor-blade-trailing-edge","history":"/api/acts/ad-ecureuil-71-amdt-4-tail-rotor-blade-trailing-edge/history","analysis":"/api/acts/ad-ecureuil-71-amdt-4-tail-rotor-blade-trailing-edge/analysis","conflicts":"/api/acts/ad-ecureuil-71-amdt-4-tail-rotor-blade-trailing-edge/conflicts","importantCases":"/api/acts/ad-ecureuil-71-amdt-4-tail-rotor-blade-trailing-edge/important-cases","documents":"/api/acts/ad-ecureuil-71-amdt-4-tail-rotor-blade-trailing-edge/documents"}}