{"id":"F2006B06713","name":"AD/S-76/30 Amdt 1 - Tail Rotor Blade Elliptical Centering Plug and Retaining Pad","slug":"ad-s-76-30-amdt-1-tail-rotor-blade-elliptical-centering-plug-and-retaining-pad","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114527,"registerId":"commonwealth-F2006B06713-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/S-76/30 Amdt 1 - Tail Rotor Blade Elliptical Centering Plug and Retaining Pad","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)  \nSikorsky S-76 Series Helicopters\n\nAD/S-76/30\n\nAmdt 1\n\nApplicability: Model S76A.\n\n  \n\nTail Rotor Blade Elliptical Centering Plug and Retaining Pad\n\n  \n12/94\n\nRequirement: Action in accordance with Sikorsky SB 76-65-35 Rev A.\n\nNote: FAA AD 94-14-20 refers. This supersedes FAA AD 84-06-02.\n\nCompliance: Unless already accomplished, within 25 hours time in service after 13 October 1994.\n\nThe effective date of the initial issue was 27 February 1984.\n\nBackground: An operator encountered severe vibration during flight while executing a left turn after take-off. Investigation revealed disbonding of the aluminium elliptical spar plug which allowed the tail rotor blade to be displaced in a radial direction. Amendment 1 withdraws the repetitive inspection requirement as a result of no further reports of failure following the inspection and modification in accordance with the Service Bulletin.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Amendment 1 narrowed ongoing obligations by withdrawing the previous repetitive inspection requirement after the Service Bulletin modification (Background). The AD still mandates the one-off modification per the service bulletin within the specified compliance time."},"complexity_factors":["Narrow applicability — applies only to Sikorsky S‑76A (Applicability: Model S76A).","Requires conformity to a manufacturer service bulletin rather than prescribing technical steps in the AD itself (Requirement: Sikorsky SB 76-65-35 Rev A).","Short compliance window creates operational scheduling pressure (Compliance: within 25 hours time in service after 13 October 1994).","Technical maintenance work on a critical rotor component (tail rotor centering plug and retaining pad) requires specialised labour and parts.","Amendment changes inspection regime (Background: withdraws repetitive inspection requirement), which affects ongoing monitoring burden for operators."],"plain_english_summary":"AD/S-76/30 Amdt 1 requires operators of Sikorsky S‑76A helicopters to modify the tail-rotor elliptical centering plug and retaining pad in accordance with Sikorsky Service Bulletin SB 76-65-35 Rev A. Compliance must be done within 25 hours time-in-service after 13 October 1994 unless already completed. Amendment 1 removes a prior repetitive inspection requirement because no further failures were reported after the inspection and modification."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This amendment narrows the scope slightly by removing the repetitive inspection requirement, making compliance simpler. It remains tightly focused on the original safety issue—the tail rotor blade centering plug defect."},"complexity_factors":["Single, specific aircraft model (S-76A) covered","One primary technical requirement referencing an external service bulletin","Simple compliance deadline (25 hours time in service after fixed date)","No defined terms section","No nested exceptions or conditional logic","Background narrative is straightforward and explains the safety rationale","Cross-reference to FAA AD is informational only, not operative"],"plain_english_summary":"This is an **Airworthiness Directive** (a mandatory safety order) for a specific helicopter model—the **Sikorsky S-76A**.\n\n**What it does:**\nIt requires owners and operators to fix a dangerous defect in the tail rotor blade. The problem involves an aluminium part called an \"elliptical centering plug\" that can come loose (disbond). If this happens, the tail rotor blade can shift out of position, causing severe vibrations that could lead to loss of control.\n\n**What action is required:**\nOperators must follow the instructions in **Sikorsky Service Bulletin 76-65-35 Rev A** to inspect and modify the tail rotor blade. This is a one-time fix—earlier versions required repeated inspections, but this update (Amendment 1) removes that requirement because the fix has proven reliable.\n\n**Who it affects:**\nAnyone who owns or operates a Sikorsky S-76A helicopter in Australia.\n\n**When it had to be done:**\nBy 25 flight hours after 13 October 1994 (unless already completed).\n\n**Why it matters:**\nA loose tail rotor blade can cause violent shaking and potentially crash the helicopter. This rule ensures the aircraft is safe to fly."}},"importantCases":[],"_links":{"self":"/api/acts/ad-s-76-30-amdt-1-tail-rotor-blade-elliptical-centering-plug-and-retaining-pad","history":"/api/acts/ad-s-76-30-amdt-1-tail-rotor-blade-elliptical-centering-plug-and-retaining-pad/history","analysis":"/api/acts/ad-s-76-30-amdt-1-tail-rotor-blade-elliptical-centering-plug-and-retaining-pad/analysis","conflicts":"/api/acts/ad-s-76-30-amdt-1-tail-rotor-blade-elliptical-centering-plug-and-retaining-pad/conflicts","importantCases":"/api/acts/ad-s-76-30-amdt-1-tail-rotor-blade-elliptical-centering-plug-and-retaining-pad/important-cases","documents":"/api/acts/ad-s-76-30-amdt-1-tail-rotor-blade-elliptical-centering-plug-and-retaining-pad/documents"}}