{"id":"F2006B04557","name":"AD/BELL 212/25 Amdt 4 - Main Rotor Yoke","slug":"ad-bell-212-25-amdt-4-main-rotor-yoke","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114287,"registerId":"commonwealth-F2006B04557-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 212/25 Amdt 4 - Main Rotor Yoke","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nBell Helicopter Textron 212 Series Helicopters\n\nAD/BELL 212/25\n\nAmdt 4\n\n  \nMain Rotor Yoke 9/91\n\nApplicability: All helicopters fitted with main rotor yoke P/N 204-011-102- (all dash numbers).\n\nRequirement: 1. Inspect the main rotor yoke in-situ in accordance with the Accomplishment Instructions in Bell Alert SB No 212-90-60, Revision A, dated 31 August 1990.\n\n2. Remove the yoke assembly from the main rotor hub assembly and inspect the yoke in accordance with FAA AD 79-20-05, Amendment 39-3662.\n\nCompliance: As detailed in the Requirement Documents.\n\nBackground: Amendment 3 implemented the additional inspections of ASB 212-87-48, which was issued as a result of fatigue cracks being found in service. It required that visual inspections of the main rotor yoke be performed daily and every 1200 hours/24 months. These are additional to the more detailed 2400 hourly inspection specified in FAA AD 79-20-05.\n\nAmendment 4 specifies Bell Alert SB 212-90-60, which supersedes ASB 212-87-48, and adds a yoke spindle inspection to Part III, required at 1200 hours/24 month intervals. Inspections done to earlier amendments may be considered for the purposes of determining when amendment 4 inspections are due.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"Amendment 4 expands the inspection regime by specifying Bell Alert SB 212-90-60 (superseding ASB 212-87-48) and by adding a yoke spindle inspection at 1,200 hours / 24 months. It also clarifies that inspections done to earlier amendments may be credited toward Amendment 4 due dates (Background)."},"complexity_factors":["References multiple external mandatory documents (Bell Alert SB 212-90-60 and FAA AD 79-20-05), requiring operators to consult and follow those texts (Requirement).","Multiple inspection frequencies and historic requirements to reconcile (daily, 1,200 hours/24 months, 2,400 hours) increase scheduling and tracking complexity (Background).","Requires both in-situ inspections and removal/bench inspections of the yoke, creating varying labour, tooling and downtime demands (Requirement).","Adds a specific yoke spindle inspection at 1,200 hours/24 months, introducing a new inspection task and potential parts/work scope (Amendment 4 / Background).","Permits crediting earlier inspections toward new due dates, which imposes record-review and interpretive burdens on operators and regulators (Amendment 4).","Wide applicability (all helicopters with P/N 204-011-102-*) makes compliance responsibilities diffuse across operators of varying scale (Applicability).","Compliance statement ties obligations to 'Requirement Documents', which can create ambiguity unless those documents are read and applied exactly (Compliance)."],"plain_english_summary":"This airworthiness directive requires Bell 212 helicopters fitted with main rotor yoke P/N 204-011-102-* to be inspected in situ under Bell Alert SB 212-90-60 and, at specified intervals, removed and inspected per FAA AD 79-20-05; it also adds a yoke spindle inspection at 1,200 hours / 24 months (Requirement; Background). The stated aim is to detect fatigue cracks; mechanically it increases recurring inspection duties, maintenance time, downtime and record-keeping for operators, while allowing earlier inspections to be credited."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment remains tightly focused on its original purpose: ensuring the airworthiness of Bell 212 main rotor yokes. While it updates the specific inspection procedures (replacing one service bulletin with another and adding a spindle inspection), it has not expanded beyond the original scope of rotor yoke safety for this specific helicopter series."},"complexity_factors":["Multiple nested document references (references to Bell Alert SB 212-90-60, FAA AD 79-20-05, and superseded ASB 212-87-48)","Amendment structure requires understanding of version history (Amendment 3 vs Amendment 4)","Dual inspection regimes (in-situ visual inspection plus removed detailed inspection)","Compliance timing references external documents rather than stating dates directly","Part number range applicability uses wildcard dash notation (\"all dash numbers\")"],"plain_english_summary":"This AD requires operators and maintenance personnel of Bell 212 helicopters with certain main rotor yokes to perform mandated inspections (in‑service visual and removed detailed checks per Bell and FAA guidance) to detect fatigue cracking that can cause catastrophic failure. As Amendment 4 it adds a spindle inspection, updates prior requirements, and allows credit for earlier compliant inspections — grounding compliance until inspections are met."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-212-25-amdt-4-main-rotor-yoke","history":"/api/acts/ad-bell-212-25-amdt-4-main-rotor-yoke/history","analysis":"/api/acts/ad-bell-212-25-amdt-4-main-rotor-yoke/analysis","conflicts":"/api/acts/ad-bell-212-25-amdt-4-main-rotor-yoke/conflicts","importantCases":"/api/acts/ad-bell-212-25-amdt-4-main-rotor-yoke/important-cases","documents":"/api/acts/ad-bell-212-25-amdt-4-main-rotor-yoke/documents"}}