{"id":"F2006B04571","name":"AD/BELL 212/4 Amdt 22 - Airworthiness Limitations","slug":"ad-bell-212-4-amdt-22-airworthiness-limitations","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114301,"registerId":"commonwealth-F2006B04571-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 212/4 Amdt 22 - Airworthiness Limitations","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)  \nBell Helicopter Textron 212 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/BELL 212/4 Amdt 21 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/BELL 212/4\n\nAmdt 22\n\n  \n\nAirworthiness Limitations 10/2000 TX\n\nApplicability: For Requirement 1: All Model 212 helicopters.\n\nFor Requirement 2: Model 212 helicopters with main rotor mast, part number 204- 011-450-001, \\-007, \\-105, \\-113, or \\-119, or main rotor trunnion part number 204-011-\n\n105-001, or \\-103, installed.\n\nRequirement: 1. Retire components from service at the times specified in the Mandatory Airworthiness Limitations Schedule, Section 4, of the Bell 212 Maintenance Manual (Revision 5 or later), with the following exceptions and additions:\n\n| Part Description                        | Part Number     | Retirement Life  |\n| --------------------------------------- | --------------- | ---------------- |\n| Skid landing gear aft cross tube        | 205-050-400-035 | 500 hours        |\n| Skid landing gear aft cross tube        | 205-050-400-053 | 1000 hours       |\n| Drive link to rotating swashplate bolts | 20-057-5-30D    | 500 hours        |\n| Float landing gear crosstube assembly   | 205-050-114-001 | Not eligible for |\n|                                         | -003            | service on       |\n|                                         | -005            | Australian       |\n|                                         | -007            | helicopters      |\n|                                         | -009            |                  |\n|                                         | -011            |                  |\n|                                         | -013            |                  |\n|                                         | 205-706-050-005 |                  |\n|                                         | -007            |                  |\n|                                         | -009            |                  |\n|                                         | -013            |                  |\n\n![](image.003.png)2. For the main rotor mast and trunnion, determine the accumulated Retirement Index Number (RIN), inspect and action in accordance with the technical requirements of FAA Emergency Airworthiness Directive 2000-15-52.\n\nNote: A copy of FAA AD 2000-15-52 may be obtained from the FAA Internet site [http://av-info.faa.gov/ad](http://av-info.faa.gov/ad) or from the Authority.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nCompliance: For Requirement 1: At the times specified in the Requirement document.\n\nFor Requirement 2: Before further flight after 9 August 2000 for paragraph (a) of the Requirement document, unless already accomplished. As specified in the Requirement document for compliance times of other required actions.\n\nThis Amendment becomes effective on 9 August 2000.\n\nBackground: This Airworthiness Directive mandates life limits and inspections for critical components, to prevent their failure in service from metal fatigue.\n\nAmendment 22 is issued in response to a new FAA AD which was prompted by a report of another cracked main rotor mast. Metallurgical inspection revealed that the mast cracked as a result of fatigue in snap ring groove radii that were smaller than the\n\n0.020 inch minimum allowable dimension. The FAA has concluded that several corrections to the RIN counting procedure are required based on a review of the fatigue data and previously issued Directives.\n\nAmendment 21 added Requirement 2, developed by Bell and the FAA to better control fatigue in the main rotor mast and trunnion following a fatigue-related accident. Requirement 1 was reformatted slightly, without technical change and became effective on 28 April 2000.\n\nAmendment 20, which updated the amendment status of the Bell 212 Maintenance Manual, became effective on 25 February 1999.\n\nAmendment 19, which introduced the Retirement Index Number limitation for the main rotor mast and trunnion, became effective on 11 September 1997.\n\nAmendment 18 of this Airworthiness Directive became effective on 5 September 1991.\n\nThe original issue of this Airworthiness Directive became effective on 31 December 1975.\n\n![](image.004.png)  \n\nDavid Alan Villiers\n\nDelegate of the Civil Aviation Safety Authority\n\n8 August 2000\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 9 August 2000.","sortOrder":0}],"analysis":{"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"},"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":true,"description":"Amendment 22 revokes the prior amendment and adds/updates requirements: it incorporates FAA Emergency AD 2000-15-52 for RIN assessment and mast/trunnion inspections, specifies or changes retirement lives for multiple parts, and declares certain float crosstube assemblies ineligible for Australian service. These changes broaden and refine the previous life‑limit and inspection obligations to address fatigue-related cracking."},"complexity_factors":["Cross-reference to external documents: Bell 212 Maintenance Manual (Revision 5+) and FAA Emergency AD 2000-15-52 required for technical detail and compliance timing.","RIN (Retirement Index Number) counting and accumulated-life procedures require altered calculation rules and record checks.","Multiple specific part numbers with differing retirement lives and an exceptions/additions table increases administrative tracking.","Some part variants are declared ineligible for Australian service, creating immediate parts-supply and installation constraints.","Compliance timing varies (e.g. 'before further flight after 9 August 2000' for certain actions) which can force urgent inspections/grounding.","Underlying technical trigger (fatigue from snap ring groove radii below 0.020 inch) introduces measurement/tolerance and metallurgical inspection requirements.","Enforcement rests with CASA delegate issuing the AD, creating regulatory discretion over implementation and acceptance of alternative methods."],"plain_english_summary":"This Airworthiness Directive requires Bell 212 operators to retire listed components at fixed life limits (per the Bell 212 Maintenance Manual, Revision 5 or later) and to determine, inspect and act on the Retirement Index Number (RIN) for main rotor masts and trunnions in accordance with FAA Emergency AD 2000-15-52. It also declares certain float crosstube assemblies ineligible for Australian service. Operators and maintenance organisations pay for inspections, part retirements and replacements; CASA enforces compliance to reduce fatigue-related failures after reports of cracked masts."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":true,"description":"Originally issued in 1975 as a basic airworthiness directive, this instrument has grown from simple component retirement rules into a complex, multi-layered safety regime. It now incorporates by reference both manufacturer maintenance manuals and foreign (US FAA) emergency directives, tracks fatigue through mathematical indices (RIN), and maintains a running exception table for Australian-specific operational conditions. The scope has expanded from 'retire parts at fixed hours' to 'dynamic fatigue monitoring with nested exceptions and external regulatory dependencies'."},"complexity_factors":["Multiple amendment history referenced (Amendments 18-22 plus original 1975 issue) creating layered context","Dual applicability structure — different requirements apply to different subsets of helicopters based on part numbers","Incorporation by reference to external documents: Bell 212 Maintenance Manual Revision 5+, FAA Emergency AD 2000-15-52","Exception/addition table modifying the incorporated manual with 10 specific part numbers and varying retirement conditions","Technical aviation terminology requiring domain knowledge (RIN, trunnion, snap ring groove radii, rotating swashplate)","Conditional compliance dates with 'before further flight' trigger and alternative 'unless already accomplished' clause"],"plain_english_summary":"This rule imposes mandatory “use‑by” retirements for specific Bell 212 parts (including certain skid tubes, rotor‑system bolts and a ban on float landing gear in Australia) and adds mandatory fatigue inspections of the main rotor mast and trunnion using a Retirement Index Number and the FAA Emergency AD 2000‑15‑52 procedures. It applies to Bell 212 owners, operators and maintenance engineers in Australia and aims to prevent catastrophic failures from metal fatigue following a discovered cracked mast."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-212-4-amdt-22-airworthiness-limitations","history":"/api/acts/ad-bell-212-4-amdt-22-airworthiness-limitations/history","analysis":"/api/acts/ad-bell-212-4-amdt-22-airworthiness-limitations/analysis","conflicts":"/api/acts/ad-bell-212-4-amdt-22-airworthiness-limitations/conflicts","importantCases":"/api/acts/ad-bell-212-4-amdt-22-airworthiness-limitations/important-cases","documents":"/api/acts/ad-bell-212-4-amdt-22-airworthiness-limitations/documents"}}