{"id":"F2006B06741","name":"AD/S-76/65 Amdt 4 - Main Rotor Shaft","slug":"ad-s-76-65-amdt-4-main-rotor-shaft","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114568,"registerId":"commonwealth-F2006B06741-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/S-76/65 Amdt 4 - Main Rotor Shaft","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)  \n![](image.002.png)  \nSikorsky S-76 Series Helicopters\n\nAIRWORTHINESS DIRECTIVE\n\n![](image.002.png)\n\n![](image.002.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/S-76/65 Amdt 3 and issues the following AD under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\nAD/S-76/65\n\nAmdt 4\n\n  \nMain Rotor Shaft 3/2001\n\nApplicability: Model S-76A, S-76B, and S-76C helicopters, with main rotor shaft assembly part number 76351-09030 series or 76351-09630 series installed.\n\nRequirement: Action in accordance with the Accomplishment Instructions of Sikorsky Aircraft Corporation Alert Service Bulletin (ASB) 76-66-32.\n\nNote 1: The fluorescent penetrant inspection specified in the Requirement document is not the fluorescent penetrant inspection contained in paragraph 4 of Chapter 20- 05-00 of the applicable maintenance manual.\n\nNote 2: FAA Emergency AD 2001-03-51 refers.\n\nCompliance: 1. Main Gear Box Assemblies containing a listed serial number 76351-09030-044 main rotor shaft specified in the Requirement document, are to be replaced before further flight after 18 January 2001, unless already accomplished.\n\n    2. Main Gear Box Assemblies containing a listed serial number 76351-09630-041 main rotor shaft specified in the Requirement document, with less than 1,000 hours time in service , are to continue the recurring Fluorescent Penetrant Inspection (FPI) previously required by ASB 76-66-31 Revision B. The FPI is to be accomplished every 20 flight hours or every 80 flights, whichever occurs first. A take-off and landing constitutes one flight. This interval begins after the last previously conducted FPI in accordance with ASB 76-66-31 Revision B.\n\nNote 3: The daily 10x visual inspection is no longer required for these main gear box assemblies.\n\n    3. Main Gear Box Assemblies containing a listed serial number 76351-09630-041 main rotor shaft specified in the Requirement document, with more than 1,000 hours time in service, are to be replaced before further flight after 18 January 2001.\n\nThis amendment becomes effective on 22 March 2001.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nBackground: The FAA received a report of a cracked main rotor shaft assembly, found during an inspection of the main transmission oil seal. The shaft had accrued 477 hours time in service when the crack was found. A cracked main rotor shaft assembly could result in failure of the shaft assembly and subsequent loss of control of the helicopter.\n\nAmendment 1 required repeat visual and NDI inspections. Additionally, the FAA has determined that certain shafts must be removed from service because the three cracked shafts discovered so far came from the same manufacturing lot.\n\nAmendment 2 was a re-issue of amendment 1 due to a gazette administration issue.\n\nAmendment 3 introduced the latest revision of the Requirement document which isolated certain main rotor shafts for further inspection and replacement.\n\nAmendment 4 is issued to reference the related FAA AD.\n\nAmendment 3 of this Airworthiness Directive became effective on 18 January 2001.\n\nAmendment 1 of this Airworthiness Directive became effective on 13 November 2000.\n\nThe original issue of this Airworthiness Directive became effective on 7 November 2000.\n\n![Signature of David Alan Villiers Delegate of the Civil Aviation Safety Authority](image.003.png)  \n\nDavid Alan Villiers\n\nDelegate of the Civil Aviation Safety Authority 9 February 2001\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 21 February 2001.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":true,"description":"The directive evolved from general repeat visual and NDI inspections (Amendment 1) to isolating and mandating removal of specific main rotor shafts from a manufacturing lot and imposing targeted recurring FPIs for others (Amendments 3–4). It also removed the prior daily 10× visual check for affected assemblies (Compliance; Note 3). Amendment 4 primarily adds reference to the related FAA Emergency AD, aligning actions with that external AD (Background; Note 2)."},"complexity_factors":["Serial‑number specific applicability increases tracking and recordkeeping (Applicability; Compliance paras 1–3).","Different requirements based on time‑in‑service thresholds (<1,000 hours vs >1,000 hours) create conditional rules (Compliance paras 2–3).","Recurring inspection interval defined as every 20 flight hours or every 80 flights imposes frequent operational downtime and monitoring (Compliance para 2).","Mandatory removals before further flight after a fixed date require immediate parts replacement or grounding (Compliance paras 1,3; effective date 22 Mar 2001).","Directive mandates compliance with an external service document (Sikorsky ASB 76‑66‑32), adding dependency on manufacturer instructions and potential interpretation issues (Requirement).","Clarifying notes exclude a common maintenance‑manual FPI method, forcing use of a specific inspection procedure (Note 1).","Cross‑reference to FAA Emergency AD links domestic compliance to foreign regulator findings, increasing regulatory interdependence (Note 2; Background)."],"plain_english_summary":"This directive requires operators of Sikorsky S‑76A/B/C helicopters fitted with main rotor shafts P/N 76351‑09030 or 76351‑09630 to follow Sikorsky ASB 76‑66‑32: specific serial‑numbered shafts must be removed from service and others must undergo recurring fluorescent penetrant inspections at 20 flight‑hour or 80‑flight intervals, with some shafts to be replaced before next flight after 18 Jan 2001. CASA enforces compliance. The action responds to reported cracked shafts from a particular manufacturing lot and shifts inspection and replacement costs and operational downtime to operators."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is Amendment 4 of an existing Airworthiness Directive. The amendments have remained tightly focused on the original safety issue (cracked main rotor shafts in S-76 helicopters). Each amendment has refined the inspection requirements and replacement criteria based on new data from the FAA and field experience, but has not expanded beyond the original scope of addressing the unsafe condition in the main rotor shaft assemblies."},"complexity_factors":["Multiple conditional compliance paths based on serial numbers and flight hours (3 distinct categories)","Cross-reference to external technical document (Sikorsky ASB 76-66-32) without reproducing its contents","Reference to related FAA Emergency AD 2001-03-51","Specific part number series (76351-09030 and 76351-09630) with specific serial numbers singled out","Amendment history tracking (4 amendments) creating layered context","Technical aviation terminology (Fluorescent Penetrant Inspection, Main Gear Box Assemblies, time in service)"],"plain_english_summary":"This Airworthiness Directive from CASA mandates inspection or replacement of main rotor shafts on Sikorsky S‑76A/B/C helicopters after cracks were found in certain 76351‑09030 and 76351‑09630 series shafts. Operators must follow Sikorsky Alert Service Bulletin 76‑66‑32.\n\nHigh‑risk shafts are grounded until replaced; lower‑hour shafts require frequent recurring inspections. The AD also removes a previous daily gearbox visual‑inspection requirement. It prevents catastrophic in‑flight shaft failure that can cause loss of control and fatal crashes."},"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-s-76-65-amdt-4-main-rotor-shaft","history":"/api/acts/ad-s-76-65-amdt-4-main-rotor-shaft/history","analysis":"/api/acts/ad-s-76-65-amdt-4-main-rotor-shaft/analysis","conflicts":"/api/acts/ad-s-76-65-amdt-4-main-rotor-shaft/conflicts","importantCases":"/api/acts/ad-s-76-65-amdt-4-main-rotor-shaft/important-cases","documents":"/api/acts/ad-s-76-65-amdt-4-main-rotor-shaft/documents"}}