{"id":"F2006B06737","name":"AD/S-76/61 - AC Generator Interlock System","slug":"ad-s-76-61-ac-generator-interlock-system","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114564,"registerId":"commonwealth-F2006B06737-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/S-76/61 - AC Generator Interlock System","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-76/61 AC Generator Interlock System 7/99\n\nTX\n\nApplicability: Model S-76A with Turbomeca Arriel 1S1 engines installed in accordance with Federal Aviation Administration Supplemental Type Certificate SH568NE, including drawing 76070-30601.\n\nRequirement: 1. Determine if the AC generator interlock relays are installed by conducting the following inspection:\n\n    uncover the No 2 relay panel located in the right side of the cockpit overhead (this panel is also referred to as the right-hand panel), and\n\n    b. inspect for the presence of the AC generator interlock relays identified as K43 and K44 (two relays) or K46, K47 and K48 (three relays).\n\nNote 1: For S-76A helicopters, Serial Number (S/N) 760001 through 760237 inclusive, the AC generator interlock relays are wired through splice groups to the K31, K32, K11 and K13 relays. For S-76A helicopters, S/N 760238 and higher, the AC generator interlock relays are wired through splice groups to the K11 and K13 relays. Depending on how and when each helicopter was modified, the labels on these relays could be K43 and K44 (two relays) or K46, K47 and K48 (three relays).\n\n    2. If, following the Requirement 1 inspection, the AC generator interlock relays are found to be installed, no further action is necessary. However, if the AC generator interlock relays are not installed, fabricate and install, in clear view of the pilot, a placard stating:\n\n“WARNING \\- AC GENERATOR INTERLOCK SYSTEM NOT INSTALLED SINGLE-ENGINE PERFORMANCE IS REDUCED”\n\nNote 2: Sikorsky Model S-76A Rotorcraft Flight Manual Supplement (RFMS) No 29B, Temporary Revision 1 dated 9 April 1999 is applicable.\n\n    3. Remove the placard installed under Requirement 2.\n\nNote 3: RFMS 29B, Temporary Revision 1, need not be complied with following installation of one of the following kits:\n\n    for Model S-76A helicopters S/N 760001 through 760237 inclusive, AC Generator Interlock Kit (Kit) Part Number (P/N) 33776-84790-012, or\n\n    b. for Model S-76A helicopters S/N 760238 and higher, Kit P/N 33776-84790-011.\n\nNote 4: FAA Priority Letter AD 99-11-04 and Sikorsky Aircraft Corporation Alert Service Bulletin 76-77-4A, Revision A, dated 6 May 1999 pertain to this Directive.\n\nCompliance: 1. Before further flight after the effective date of this Directive.\n\n    2. Before further flight after the Requirement 1 inspection is completed.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n    3. Concurrent with installation of one of the following kits:\n\n    for Model S-76A helicopters S/N 760001 through 760237 inclusive, AC Generator Interlock Kit (Kit) Part Number (P/N) 33776-84790-012, or\n\n    b. for Model S-76A helicopters S/N 760238 and higher, Kit P/N 33776-84790- 011.\n\nThis Airworthiness Directive becomes effective on 25 May 1999.\n\nBackground: The FAA has advised that S-76A helicopters with Turbomeca Arriel 1S1 may fail to achieve the specified single engine performance if the AC generator interlock system is not installed. This Directive requires an inspection to determine if the AC generator interlock system is installed and, if necessary, the installation of a warning placard.\n\nThe Directive also provides for an optional terminating action allowing removal of the placard and operation limitation imposed by the temporary RFMS revision.","sortOrder":0}],"analysis":{"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 is a standard Airworthiness Directive with a focused, narrow scope. It addresses a specific safety deficiency in a specific helicopter model with specific engine configurations. The document maintains its original intent: ensuring the AC generator interlock system is present or appropriately flagged until remedied."},"complexity_factors":["Multiple serial number breakpoints (760001-760237 vs 760238+) with different wiring configurations and different part numbers for remedy kits","Conditional logic: inspection outcome determines whether placard installation is required","Cross-references to external documents: FAA Supplemental Type Certificate SH568NE, Sikorsky RFMS No 29B Temporary Revision 1, FAA AD 99-11-04, and Sikorsky Alert Service Bulletin 76-77-4A","Technical aviation terminology requiring specialized knowledge (relay designations K43/K44 vs K46/K47/K48, splice groups, RFMS)","Three separate compliance dates tied to different trigger events (effective date, inspection completion, kit installation)"],"plain_english_summary":"This Airworthiness Directive affects Sikorsky S‑76A helicopters equipped with Turbomeca Arriel 1S1 engines and requires a cockpit inspection (before next flight) to verify whether the AC generator interlock relays are installed. If the interlock system is missing, operators must immediately install a pilot‑visible warning placard stating: \"WARNING - AC GENERATOR INTERLOCK SYSTEM NOT INSTALLED SINGLE-ENGINE PERFORMANCE IS REDUCED.\" The placard may be removed once the proper upgrade kit is installed."},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The directive’s scope is aligned with the stated safety concern: it limits action to inspecting for the AC generator interlock relays, fitting a warning placard if absent, and allowing removal of the placard only upon installation of specified interlock kits (Requirements 1–3; Notes 1–3). It does not expand beyond these corrective and procedural measures or impose broader operational restrictions beyond the referenced temporary RFMS revision."},"complexity_factors":["Narrow, technical applicability: limited to S‑76A with Arriel 1S1 engines installed per FAA STC SH568NE, including a specific drawing (Applicability).","Serial‑number split changes wiring and kit part numbers (S/N 760001–760237 vs 760238+) and affects which relays/splice groups are relevant (Note 1; Note 3).","Multiple possible relay configurations and labels (K43/K44 or K46/K47/K48) increase inspection ambiguity (Requirement 1; Note 1).","Physical inspection step requires access to and uncovering the No.2 relay panel in the cockpit overhead (Requirement 1).","Immediate operational impact: compliance deadlines are 'before further flight' after the effective date or inspection (Compliance).","Mitigation path combines a low‑tech interim fix (fabricate/install placard) with an optional terminating action that requires procuring and installing specific kits by P/N (Requirement 2; Requirement 3; Note 3).","Cross‑references to FAA Priority Letter AD, Sikorsky Alert Service Bulletin, and a temporary RFMS revision add procedural and documentation compliance layers (Note 4; Note 2)."],"plain_english_summary":"Requires operators of Sikorsky S‑76A helicopters modified with Turbomeca Arriel 1S1 engines (per FAA STC SH568NE) to inspect the cockpit right‑hand No.2 relay panel to confirm whether the AC generator interlock relays are fitted. If the relays are absent, a pilot‑visible warning placard must be fitted before further flight; installing a specified interlock kit (by serial‑number range) removes the placard and associated temporary flight‑manual limitation. The AD responds to a reported risk of reduced single‑engine performance when the interlock system is missing."}},"importantCases":[],"_links":{"self":"/api/acts/ad-s-76-61-ac-generator-interlock-system","history":"/api/acts/ad-s-76-61-ac-generator-interlock-system/history","analysis":"/api/acts/ad-s-76-61-ac-generator-interlock-system/analysis","conflicts":"/api/acts/ad-s-76-61-ac-generator-interlock-system/conflicts","importantCases":"/api/acts/ad-s-76-61-ac-generator-interlock-system/important-cases","documents":"/api/acts/ad-s-76-61-ac-generator-interlock-system/documents"}}