{"id":"F2009L00677","name":"AD/ECUREUIL/131 Amdt 1 - Stabiliser Upper and Lower Fin Attachment Fitting - Modification","slug":"ad-ecureuil-131-amdt-1-stabiliser-upper-and-lower-fin-attachment-fitting-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":77603,"registerId":"commonwealth-F2009L00677-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/131 Amdt 1 | Stabiliser Upper and Lower Fin Attachment Fitting - Modification | 4/2009 DM |\n| ---------------------- | ---------------------------------------------------------------- | --------- |\n\n| Applicability: | Model AS 350 B, B1, B2, B3, BA, BB and D helicopters, all serial numbers, fitted with the following upper and lower fins on which Modification (MOD) 073330 has not been incorporated:Upper fin assembly part numbers: 350A14-0020-00XX, -01XX, -02XX, -03XX,-08XX, -09XX, -10XX, -17XX, -18XX, -19XX, and part number 350A64-1144-00XX.Lower fin assembly part numbers: 350A14-0021-00XX, -01XX, -02XX, -03XX, and -04XX. |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | Required as indicated, unless already accomplished.1. For AS 350 B, B1, B2, BA, BB and D helicopters:No later than 31 March 2009, remove the fins, modify the upper and lower fittings on the tail boom by increasing the diameter of the bolt holes, and replace bolts part number 22126BV060032L and washers part number 23112AG060LE with special bolts part number 350A23-4016-20 and special washers part number 350A23-4017-22; in accordance with EUROCOPTER AS 350 Alert Service Bulletin (ASB) No. 55.00.16 Revision 1 (MOD 073330), or later EASA approved revision.2. For AS 350 B3 helicopters equipped with the upper fin pre MOD 073148:a. For helicopters with upper and lower fins pre MOD 073288:(i) For helicopters which have accumulated less than 110 flight hours after 15 March 2006:Within 110 flight hours after 15 March 2006, replace upper and lower fin attachment screws in accordance with paragraph 2.B.1 and 2.B.2 of ASB No. 55.00.13 Revision 2 (MOD 073288), or later EASA approved revision. |\n\n| | (ii) For helicopters which have accumulated more than 110 flight hours after 15 March 2006:Within 15 flight hours after 26 February 2009, replace upper and lower fin attachment screws in accordance with paragraph 2.B.1 and 2.B.2 of ASB No. 55.00.13 Revision 2, or later EASA approved revision.(iii) At intervals not exceeding 110 flight hours, check the tightening torque of the upper fin attachment screws and check the upper fin reinforcement splice for cracks and loosened rivets in accordance with the instructions specified in paragraph 2.B.3 of ASB No. 55.00.13 Revision 2, or later EASA approved revision.(iv) In the case of cracks, loosened rivets in the reinforcement splice or if the tightening torque of one or both of the attachment screws is less than 80% of the minimum torque value, before further flight, apply associated corrective actions in accordance with the instructions of paragraph 2.B.3.a.1, 2.B.3.a.2, or 2.B.3.a.3 (as applicable) of ASB 55.00.13 Revision 2, or later EASA approved revision.b. For helicopters with upper and lower fins post MOD 073288:(i) For helicopters which have accumulated less than 110 flight hours since the latest check performed in accordance with paragraph 2.B.3 of ASB No. 55.00.13 Revision 0, or later EASA approved revision:Within 110 flight hours after the latest check performed in accordance with paragraph 2.B.3 of ASB No. 55.00.13 Revision 0, or later EASA approved revision, check the tightening torque of the upper fin attachment screws and check the upper fin reinforcement splice for cracks and loosened rivets in accordance with the instructions specified in paragraph 2.B.3 of ASB No. 55.00.13 Revision 2, or later EASA approved revision. Repeat thereafter at intervals not to exceed 110 flight hours.(ii) For helicopters which have accumulated more than 110 flight hours since the latest check performed in accordance with paragraph 2.B.3 Revision 0, or later EASA approved revision:Within 15 flight hours after 26 February 2009, check the tightening torque of the upper fin attachment screws and check the upper fin reinforcement splice for cracks and loosened rivets in accordance with the instructions specified in paragraph 2.B.3 of ASB No. 55.00.13 Revision 2, or later EASA approved revision. Repeat thereafter at intervals not to exceed 110 flight hours. |\n| --- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n| | (iii) In the case of cracks, loosened rivets in the reinforcement splice or if the tightening torque of one or both of the attachment screws is less than 80% of the minimum torque value, before further flight, apply the associated corrective actions in accordance with the instructions of paragraph 2.B.3.a.1, 2.B.3.a.2, or 2.B.a.3 (as applicable) of ASB 55.00.13 Revision 2, or later EASA approved revision.3. For all AS 350 B3 helicopters:Unless already accomplished, no later than 31 March 2009, remove the fins, modify the upper and lower fittings on the tail boom by increasing the diameter of the bolt holes, and replace bolts part number 22126BV060032L and washers part number 23112AG060LE with special bolts part number 350A23-4016-20 and special washers part number 350A23-4017-22; in accordance with ASB No. 55.00.16 Revision 1, (MOD 073330), or later EASA approved revision.Compliance with Requirement 3 of this Directive is considered as acceptable compliance with Requirements 2.a.(i) and 2.a.(ii), and terminating action for the repetitive checks of Requirements 2.a.(iii), 2.b.(i) and 2.b.(ii) of this Directive.4. After 31 March 2009, upper and lower fins with part numbers listed in the applicability section of this Directive, and held as spares, shall not be installed on any helicopter unless MOD 073330 has been incorporated.Note: EASA AD 2009-0030 refers. |\n| ----------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Compliance: | As specified in Requirements 1, 2, 3 and 4. |\n| | This Amendment becomes effective on 26 February 2009. |\n| Background: | The EASA received several reports of cracking in the stabiliser upper fin of Model AS 355 N helicopters. The growth of a crack in a fin attachment spar, unless detected and corrected, could lead to failure of the spar and loss of the fin.The EASA AD related to this Directive, AD 2008-0121, supersedes EASA ADs 2006-0060-E (AD/ECUREUIL/118) and 2006-0095 (AD/ECUREUIL/107 Amdt 1), and thereby constitutes terminating action to the requirements of these CASA ADs. |\n\n| | Amendment 1 is issued in response to a new EASA AD, which adds new upper and lower fin assembly part numbers to applicability and includes repetitive checks for some AS 350 B3 helicopters until accomplishment of MOD 073330. |\n| --- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png) \nDavid Villiers \nDelegate of the Civil Aviation Safety Authority\n\n18 February 2009","sortOrder":0},{"sectionNumber":"AD/ECUREUIL/131 Amdt 1","sectionType":"part","heading":"AD/ECUREUIL/131 Amdt 1","content":"## AD/ECUREUIL/131 Amdt 1","sortOrder":1},{"sectionNumber":"Stabiliser Upper and Lower Fin Attachmen","sectionType":"part","heading":"Stabiliser Upper and Lower Fin Attachment Fitting - Modification","content":"## Stabiliser Upper and Lower Fin Attachment Fitting - Modification","sortOrder":2},{"sectionNumber":"4/2009 DM","sectionType":"part","heading":"4/2009 DM","content":"## 4/2009 DM","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":7,"scope_assessment":{"changed":true,"description":"Amendment 1 expands scope from the prior AD by adding additional upper and lower fin assembly part numbers to the applicability and by introducing repetitive torque checks and inspections for certain AS 350 B3 helicopters until MOD 073330 is embodied. It also clarifies that incorporation of MOD 073330 is terminating action for the interim requirements (Amendment note; Requirements 2 and 3)."},"complexity_factors":["Detailed part‑numbered applicability covering many fin assembly P/Ns and specific AS350 submodels (Applicability).","Model‑specific, conditional compliance paths: immediate mandatory MOD for many models versus interim inspection/ screw replacement regimes for some B3 helicopters (Requirements 1–3).","Multiple deadlines and repeating intervals (e.g. 31 March 2009; checks at intervals not exceeding 110 flight hours; 15 flight hours for accelerated action) creating operational scheduling complexity (Requirements 1–3).","Cross‑references to external technical documents: Eurocopter ASB No. 55.00.16 Revision 1, ASB No. 55.00.13 Revision 2, and any later EASA‑approved revisions — compliance depends on these documents (Requirements 1–3).","Technical pass/fail criteria embedded (torque thresholds: <80% of minimum torque triggers corrective action; inspections for cracks and loosened rivets) requiring maintenance precision and recordkeeping (Requirement 2.a.(iv) and 2.a.(iii)).","Terminating action and equivalence rules: accomplishment of MOD 073330 terminates repetitive checks and is treated as acceptable compliance for earlier interim requirements (Requirement 3).","Operational restriction on spare parts: ban on installing listed spare fins after a set date unless MOD incorporated, affecting inventory management (Requirement 4).","Dependence on regulator discretion and approved revisions (EASA approval) introduces regulatory sequencing and potential approval delays impacting compliance timing (Requirements 1–3)."],"plain_english_summary":"This directive requires removing certain upper and lower stabiliser fins on specified Eurocopter AS 350 models, enlarging the tail‑boom fin fitting bolt holes and replacing bolts and washers with specified parts in accordance with Eurocopter ASB (MOD 073330). For some AS 350 B3 helicopters it allows interim repetitive torque checks and inspections until the modification is done. Owners/operators and maintenance organisations must meet the specified deadlines, follow EASA‑approved ASB revisions, and bear the cost and labour of modification or recurring inspections to reduce risk of fin attachment failure."},"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":7,"scope_assessment":{"changed":true,"description":"The original AD (implied by Amendment 1) has expanded significantly. The amendment adds new fin part numbers to the applicability list, introduces an entirely new compliance path for AS 350 B3 helicopters with complex interim inspection requirements, and references additional service bulletins. What began as a straightforward modification order has grown into a multi-track directive with repetitive inspections, flight-hour calculations, and variant-specific deadlines."},"complexity_factors":["Multiple aircraft model variants with different compliance paths (B/B1/B2/BA/BB/D vs B3)","Nested conditional logic: B3 requirements split based on whether fins are 'pre' or 'post' MOD 073148, then further split based on MOD 073288 status, then further split based on accumulated flight hours since specific dates","Cross-references to three different Eurocopter Alert Service Bulletins (ASB 55.00.16 Rev 1, ASB 55.00.13 Rev 2, ASB 55.00.13 Rev 0) with specific paragraph citations","Multiple modification numbers referenced as status markers (MOD 073330, MOD 073148, MOD 073288) that determine applicability","Terminating action provisions — completing Requirement 3 cancels out Requirements 2.a.(i), 2.a.(ii) and stops the repetitive checks in 2.a.(iii), 2.b.(i), 2.b.(ii)","Specific part number ranges with wildcards (XX suffixes) for upper and lower fin assemblies","Flight hour-based compliance windows (110 hours, 15 hours) tied to specific calendar dates (15 March 2006, 26 February 2009)","Torque percentage threshold (80% of minimum) triggering immediate corrective action","Reference to external EASA AD 2009-0030 and superseded directives (AD 2008-0121, AD 2006-0060-E, AD 2006-0095)"],"plain_english_summary":"This CASA Airworthiness Directive orders owners/operators of certain Eurocopter AS350 (Ecureuil/Squirrel) helicopters to address cracking in tail‑boom stabiliser fin attachments that could cause in‑flight fin loss. Affected helicopters are specified AS350 B/B1/B2/B3/BA/BB/D models without factory MOD 073330. Required actions include bolt‑hole modification, stronger fasteners, interim inspections/parts replacements for some B3s, and a March 31, 2009 compliance deadline; unmodified spare fins are banned thereafter."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ecureuil-131-amdt-1-stabiliser-upper-and-lower-fin-attachment-fitting-modification","history":"/api/acts/ad-ecureuil-131-amdt-1-stabiliser-upper-and-lower-fin-attachment-fitting-modification/history","analysis":"/api/acts/ad-ecureuil-131-amdt-1-stabiliser-upper-and-lower-fin-attachment-fitting-modification/analysis","conflicts":"/api/acts/ad-ecureuil-131-amdt-1-stabiliser-upper-and-lower-fin-attachment-fitting-modification/conflicts","importantCases":"/api/acts/ad-ecureuil-131-amdt-1-stabiliser-upper-and-lower-fin-attachment-fitting-modification/important-cases","documents":"/api/acts/ad-ecureuil-131-amdt-1-stabiliser-upper-and-lower-fin-attachment-fitting-modification/documents"}}