{"id":"F2006B09316","name":"AD/EC 135/2 - Tail Rotor Drive Shaft Bearing Attachment Flange","slug":"ad-ec-135-2-tail-rotor-drive-shaft-bearing-attachment-flange","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":53447,"registerId":"commonwealth-F2006B09316-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/EC 135/2 - Tail Rotor Drive Shaft Bearing Attachment Flange","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nEurocopter EC 135 Series Helicopters\n\nAD/EC 135/2 Tail Rotor Drive Shaft Bearing Attachment Flange 2/2000\n\nTX\n\nApplicability: All Model EC 135 helicopters, serial numbers 0005 through 0120.\n\nRequirement: Inspect in accordance with Eurocopter Deutschland Alert Service Bulletin EC 135- 53A-010 Revision 2.\n\nNote: LBA AD 1999-199/3 refers.\n\nCompliance: Before further flight after 24 December 1999 for the initial inspection, and before the installation of the additional bearing support bracket, unless already accomplished.\n\nAction, thereafter as specified in the Requirement document.\n\nThis Airworthiness Directive becomes effective on 24 December 1999.\n\nBackground: A report was received of a crack that was detected on the attachment flange of the tail rotor drive shaft bearing. Initial and repeat inspections are introduced that are intended to prevent a fracture of the bearing attachment flange of the tail rotor drive shaft, which could result in serious malfunction of the helicopter.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in a specific aircraft model range. It has not expanded beyond its original purpose of mandating inspections for the tail rotor drive shaft bearing flange crack issue."},"complexity_factors":["Very short document (under 200 words)","Only one defined applicability range (serial numbers 0005-0120)","Single primary requirement referencing an external technical document (the Eurocopter Service Bulletin)","Simple compliance timeline (before further flight after specific date)","No nested exceptions or conditional logic","Cross-reference to one German aviation authority document (LBA AD 1999-199/3) and one external manufacturer bulletin, but these don't create interpretive complexity"],"plain_english_summary":"CASA requires owners/operators of Eurocopter EC135 helicopters (S/N 0005–0120) to inspect the tail-rotor drive‑shaft bearing attachment flange for cracks before further flight after 24 December 1999 and to perform follow-up inspections or fit an additional bearing support bracket per Eurocopter ASB EC135‑53A‑010 Rev 2.\n\nA cracked flange could lead to tail‑rotor failure and loss of control; this AD is mandatory and legally enforceable."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD applies to EC 135 helicopters serial numbers 0005–0120 and mandates inspections per the specified Eurocopter service bulletin to prevent flange fracture. The stated scope and measures align with the AD's stated safety purpose; no change from that original intent is indicated in the text."},"complexity_factors":["Narrow applicability to a specific helicopter model and serial-number range (Applicability)","Mandatory compliance timing: ‘before further flight’ and before installation of a support bracket — operational scheduling impact (Compliance)","Delegation of inspection details and repeat schedules to an external manufacturer service bulletin increases reliance on and interpretation of that document (Requirement)","Safety-critical failure mode (flange fracture) requires prompt execution and may lead to grounded aircraft if defects found (Background)","Possible follow-on work (installation of additional bearing support bracket) could involve parts, labour and further downtime (Compliance/Requirement)"],"plain_english_summary":"This Airworthiness Directive requires operators of Eurocopter EC 135 helicopters (serial numbers 0005–0120) to inspect the tail-rotor drive-shaft bearing attachment flange following Eurocopter Alert Service Bulletin EC135‑53A‑010 Revision 2 (Applicability; Requirement).\n\nInspections must be done before further flight after 24 December 1999 and before installing an additional bearing-support bracket, with further action as specified in the service bulletin. The measure is intended to prevent flange fracture that could cause serious helicopter malfunction (Compliance; Background)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ec-135-2-tail-rotor-drive-shaft-bearing-attachment-flange","history":"/api/acts/ad-ec-135-2-tail-rotor-drive-shaft-bearing-attachment-flange/history","analysis":"/api/acts/ad-ec-135-2-tail-rotor-drive-shaft-bearing-attachment-flange/analysis","conflicts":"/api/acts/ad-ec-135-2-tail-rotor-drive-shaft-bearing-attachment-flange/conflicts","importantCases":"/api/acts/ad-ec-135-2-tail-rotor-drive-shaft-bearing-attachment-flange/important-cases","documents":"/api/acts/ad-ec-135-2-tail-rotor-drive-shaft-bearing-attachment-flange/documents"}}