{"id":"F2006B06747","name":"AD/S-76/71 - Rotor Brake Disc","slug":"ad-s-76-71-rotor-brake-disc","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114574,"registerId":"commonwealth-F2006B06747-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# ![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (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\n![](image.001.png)\n\nSikorsky S- 76 Series Helicopters","sortOrder":0},{"sectionNumber":"AD/S-76/71 Rotor Brake Disc 4/2003 TX","sectionType":"part","heading":"AD/S-76/71 Rotor Brake Disc 4/2003 TX","content":"# AD/S-76/71 Rotor Brake Disc 4/2003 TX\n\nApplicability: Model S \\- 76A, B, and C helicopters.\n\nRequirement: 1. Determine the manufacturer of each rotor brake disc (RBD) by examining the part number (P/N) markings and accomplish the following requirements based on the identification of the RBD.\n\n    If the P/N is 76363-09101-102, the manufacturer is Goodyear. No further action is required by this directive.\n\n    b. If the P/N 76363-09103-102 is pressure stamped on the RBD, the manufacturer is BF Goodrich. No further action is required by this directive.\n\n    c. If the P/N 76363-09103-102 is electrolytically etched on the RBD, the manufacturer is Parker Hannifin Corporation (PHC).\n\n    For each PHC RBD with a P/N 76363-0913-102 and serial number (S/N) other than 38 through 379, remark the P/N as 76363-090103-105 using the vibropeen method. After remarking no further action is required.\n\n    ii. If the RBD serial number or the manufacturer cannot be determined and for RBD’s with P/N 76363-09103-102 and S/N’s 38 through 379, reidentify or mark the P/N as 76363-09103-104, or replace the RBD in accordance with requirement 3 of this directive.\n\n    2. For RBD’s with P/N 76363-0103-104, inspect the RBD for cracks as detailed in Figure 1.\n\n    If a crack is found extending through the entire RBD thickness as detailed in Figure 1, View A, replace the RBD with a serviceable RBD other than P/N 76363-09103-104.\n\n    b. If 2 or more surface cracks are found located between adjacent boltholes as shown in Figure 1, View B, replace the RBD with a serviceable RBD other than P/N 76363-09103-104.","sortOrder":1}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This appears to be a standard, targeted airworthiness directive focused on a specific safety issue with rotor brake discs on Sikorsky S-76 helicopters. The scope remains tightly constrained to identifying and remediating a known unsafe condition with specific part numbers and manufacturers. No evidence of scope creep beyond original aviation safety purpose."},"complexity_factors":["Multiple nested conditional branches (if/then logic based on part number, manufacturing method, and serial number ranges)","Specific technical terminology requiring aviation engineering knowledge (vibropeen method, electrolytically etched, pressure stamped)","Cross-references between requirements (requirement 2 references requirement 3 for replacement, though requirement 3 text is truncated/incomplete in this extract)","Precise serial number ranges (S/N 38 through 379) that must be correctly interpreted","Visual inspection requirements referencing Figure 1 (not included in text) with specific crack patterns in View A and View B"],"plain_english_summary":"This CASA Airworthiness Directive targets misidentified rotor brake discs on Sikorsky S‑76A/B/C helicopters that can develop dangerous cracks. It requires operators to check disc markings and, for suspect Parker Hannifin or unidentifiable parts, re‑mark or replace them and to inspect certain marked discs for cracking.\n\nThe rule prevents in‑service brake‑disc failure that could lead to loss of braking control, reducing risk to aircraft and crews."},"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"},"flash_summary":{"complexity_score":7,"scope_assessment":{"changed":false,"description":"The directive confines action to Sikorsky S‑76A/B/C helicopters and to specific rotor brake disc part numbers and serial‑number ranges (Applicability; Requirement 1–2). It focuses on identification, remarking and inspection/replacement to address the unsafe condition described; there is no text in the excerpt indicating an expansion beyond those targeted parts or models."},"complexity_factors":["Multiple part‑number pathways and manufacturer rules (Requirement 1): operators must determine manufacturer by P/N marking and follow different actions for Goodyear, BF Goodrich and PHC discs.","Serial‑number dependent outcomes (Requirement 1.c.i–ii): actions differ for PHC RBDs depending on S/N ranges (e.g. S/Ns 38–379 vs others).","Specialised remarking method required (Requirement 1.c.i): vibropeen remarking imposes tooling and skills demands.","Inspection criteria reference external figure (Requirement 2): crack definitions depend on Figure 1 (not included here), creating interpretation and training needs.","Replacement constraints (Requirement 2.a–b): when cracks meet defined criteria, discs must be replaced with a serviceable RBD other than P/N 76363-09103-104, narrowing acceptable spares.","Cross‑reference to non‑included material (references to Requirement 3 and figures): the AD refers to additional requirements and illustrations not present in the excerpt, increasing implementation ambiguity.","Operational burdens: physical removal/inspection of rotor brake discs, recordkeeping of reidentified/remarked P/Ns and S/Ns, and potential parts supply or grounding time.","Regulatory enforcement: issued under the CASA delegate power (subregulation 39.1(1) of CAR 1998), creating a mandatory compliance obligation with limited operator discretion."],"plain_english_summary":"This Airworthiness Directive requires operators of Sikorsky S‑76A/B/C helicopters to identify rotor brake discs by part and serial number, re‑mark certain Parker Hannifin discs, and inspect or replace discs with specific part numbers for cracking. The regulator’s delegate mandates compliance; operators bear the cost of inspections, marking (vibropeen) and any replacements. The directive uses serial‑number rules and visual/figure‑based crack criteria to decide whether a disc must be reidentified, remarking or removed from service."}},"importantCases":[],"_links":{"self":"/api/acts/ad-s-76-71-rotor-brake-disc","history":"/api/acts/ad-s-76-71-rotor-brake-disc/history","analysis":"/api/acts/ad-s-76-71-rotor-brake-disc/analysis","conflicts":"/api/acts/ad-s-76-71-rotor-brake-disc/conflicts","importantCases":"/api/acts/ad-s-76-71-rotor-brake-disc/important-cases","documents":"/api/acts/ad-s-76-71-rotor-brake-disc/documents"}}