{"id":"F2007L01684","name":"AD/S-76/75 - Main Rotor Shaft - 2","slug":"ad-s-76-75-main-rotor-shaft-2","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":66361,"registerId":"commonwealth-F2007L01684-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Sikorsky S-76 Series Helicopters","sectionType":"division","heading":"Sikorsky S-76 Series Helicopters","content":"### Sikorsky S-76 Series Helicopters\n\n| AD/S-76/75 | Main Rotor Shaft - 2 | 8/2007 DM |\n| ---------- | -------------------- | --------- |\n\n| Applicability: | Model S-76A, B, and C helicopters equipped with a main rotor shaft assembly listed below:a. Part number 76351-09030-all dash numbers, and with a following serial number:B015-00782 through B015-00791, B015-00811 through B015-00816,E015-00844 through E015-00865, and E015-00908 through E015-00918.b. Part number 76351-09630-041, and with a following serial number:C213-00436 through C213-00454, D213-00537 through D213-00545, andD213-00575 through D213-00585.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Perform an ultrasonic inspection of the main rotor shaft assembly for cracking:1. For Model S-76A, B, and C helicopters equipped with a main rotor shaft assembly part number 76351-09630-041, remove and inspect the shaft assembly in accordance with the Accomplishment Instructions, paragraphs 3.B.(1)(a) through 3.B.(1)(d)5 of Sikorsky Alert Service Bulletin (ASB) No. 76-66-45A Revision A, dated 7 February 2007, or later FAA approved revision.2. For Model S-76A helicopters equipped with a main rotor shaft assembly part number 76351-09030-all dash numbers, remove and inspect the shaft assembly in accordance with the Accomplishment Instructions, paragraphs 3.B.(1)(a) through 3.B.(1)(d)5 of ASB No. 76-66-46, dated 7 February 2007, or later FAA approved revision.If a crack is detected, before further flight, replace the main rotor shaft assembly with a serviceable shaft assembly that has been ultrasonically inspected in accordance with Requirement 1 or 2, as applicable.Reassemble the lower bearing housing assembly, install the main gear box, and perform the ground run leak test in accordance with the Accomplishment Instructions, paragraphs 3.B.(1)(f) through 3.B.(1)(l) of ASB No. 76-66-45A Revision A or ASB No. 76-66-46, as applicable; or later FAA approved revision. |\n\n|             | Before installing an affected main rotor shaft assembly, ultrasonically inspect the shaft assembly in accordance with Requirement 1 or 2, as applicable; reassemble the lower bearing housing assembly, install the main gearbox, and perform the ground leak test as specified in the previous Requirement paragraph.Note: FAA AD 2007-11-05 Amdt 39-15062 refers. |\n| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Compliance: | For Requirement 1 and 2: Within 75 hours time in service after 15 June 2007, unless already accomplished.                                                                                                                                                                                                                                                           |\n|             | This Airworthiness Directive becomes effective on 15 June 2007.                                                                                                                                                                                                                                                                                                     |\n| Background: | The FAA received a report of cracking that had occurred during the manufacture of certain main rotor shafts. Undetected cracking in the main rotor shaft could result in separation of the main rotor, and subsequent loss of control of the helicopter.                                                                                                            |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n6 June 2007","sortOrder":0},{"sectionNumber":"AD/S-76/75","sectionType":"part","heading":"AD/S-76/75","content":"## AD/S-76/75","sortOrder":1},{"sectionNumber":"Main Rotor Shaft - 2","sectionType":"part","heading":"Main Rotor Shaft - 2","content":"## Main Rotor Shaft - 2","sortOrder":2},{"sectionNumber":"8/2007 DM","sectionType":"part","heading":"8/2007 DM","content":"## 8/2007 DM","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The directive sets a targeted inspection and replacement requirement for identified main rotor shafts; the text does not indicate an expansion or contraction of scope from a prior stated intent within this instrument."},"complexity_factors":["Technical inspection requirement: ultrasonic inspection of a critical rotating component (requires qualified NDT personnel and equipment).","Precise applicability: limited to specific part numbers and multiple serial‑number ranges, increasing identification and record‑checking work.","Dependency on external documents: references Sikorsky Alert Service Bulletins (and FAA revisions) for detailed procedures.","Mandatory removal, inspection and replacement workflow: physical disassembly, reassembly and ground leak/run tests required.","Short compliance window: 75 hours time‑in‑service from an effective date creates scheduling and operational impacts.","Pre‑installation mandate: inspection required before installing any affected shaft, affecting parts logistics and resale/installation practices."],"plain_english_summary":"This Airworthiness Directive requires ultrasonic inspection of certain Sikorsky S‑76A/B/C main rotor shafts identified by part number and serial ranges, with removal and inspection, replacement before further flight if cracks are found, and a pre‑installation inspection for affected shafts. Compliance (or prior accomplishment) is due within 75 flight hours after 15 June 2007. The AD is presented as a safety measure to address manufacturing cracking that the regulator says could cause main rotor separation and loss of control."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — addressing a specific manufacturing defect in specific serial numbers of main rotor shafts for the S-76 helicopter series. It has not expanded beyond this original safety purpose."},"complexity_factors":["Multiple overlapping applicability criteria requiring cross-referencing of part numbers AND serial number ranges","Two separate technical compliance paths depending on exact part number (ASB 76-66-45A Revision A vs ASB 76-66-46)","Extensive cross-referencing to external FAA documents and Sikorsky service bulletins not reproduced in the AD","Conditional logic: different requirements for 'if crack detected' vs 'before installing affected shaft'","Specific procedural sub-paragraph references (3.B.(1)(a) through 3.B.(1)(d)5) requiring access to original manufacturer documentation","Dual effective dates: compliance deadline (75 hours after 15 June 2007) vs effective date (15 June 2007)"],"plain_english_summary":"This CASA Airworthiness Directive mandates ultrasonic inspection of main rotor shaft assemblies on specified Sikorsky S‑76A/B/C helicopters (certain part/serial numbers) within 75 flight hours of 15 June 2007. Affected shafts must be inspected before installation, and any shaft found cracked must be replaced before further flight.\n\nIssued after the FAA found manufacturing cracks that could cause rotor separation and catastrophic loss of control, the AD forces immediate checks to prevent fatal accidents."}},"importantCases":[],"_links":{"self":"/api/acts/ad-s-76-75-main-rotor-shaft-2","history":"/api/acts/ad-s-76-75-main-rotor-shaft-2/history","analysis":"/api/acts/ad-s-76-75-main-rotor-shaft-2/analysis","conflicts":"/api/acts/ad-s-76-75-main-rotor-shaft-2/conflicts","importantCases":"/api/acts/ad-s-76-75-main-rotor-shaft-2/important-cases","documents":"/api/acts/ad-s-76-75-main-rotor-shaft-2/documents"}}