{"id":"F2006B04586","name":"AD/BELL 212/54 - Main Transmission Lower Planetary Spider","slug":"ad-bell-212-54-main-transmission-lower-planetary-spider","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114322,"registerId":"commonwealth-F2006B04586-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 212/54 - Main Transmission Lower Planetary Spider","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)  \nBell Helicopter Textron 212 Series Helicopters\n\nAD/BELL 212/54 Main Transmission Lower Planetary Spider 2/95\n\nApplicability: All Bell Helicopter Textron 212 Series Helicopters with main transmission lower planetary spider P/N 412-040-785-101 installed.\n\nRequirement: Retire the spider from service.\n\nNote 1: FAA AD 94-18-09 Amdt 39-9022 and Bell Alert Service Bulletin ASB 212- 93-83 Revision A refer.\n\nNote 2: The life of Spider P/N 412-040-785-103 is not limited by this AD.\n\nCompliance: Retire the spiders before 2500 hours time in service or within 100 hours time in service after 2 February 1995, whichever is the later.\n\nBackground: Five failures of the main transmission lower planetary spider have been experienced during the manufacturer’s fatigue tests. Accordingly a fatigue life has been established to prevent in service failures.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue safety directive targeting one specific part on one helicopter model. It has not expanded beyond its original purpose of addressing the identified fatigue failure risk."},"complexity_factors":["Single, unambiguous operative requirement ('Retire the spider from service')","Only one defined term of significance ('time in service' — standard aviation term)","Simple compliance formula with two alternative deadlines (whichever is later)","No cross-references to other legislation sections — only references to related FAA and manufacturer documents for context","No conditional logic, exceptions, or nested provisions","Extremely short document (under 200 words of operative text)"],"plain_english_summary":"CASA orders mandatory retirement of main transmission lower planetary spider P/N 412-040-785-101 from Bell Helicopter Textron 212 series helicopters in Australia, due to five fatigue-test failures that could cause catastrophic gearbox loss.  \n\nThe part must be removed before 2,500 flight hours (or within 100 flight hours after 2 February 1995, whichever allows more time); continuing to fly with it past the limit is illegal. P/N 412-040-785-103 is not affected."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive maintains a narrow, preventive scope: it mandates retirement of a specific part to address fatigue-test failures and does not expand to other components. It distinguishes an alternative part number as unaffected (Note 2) and sets a fixed life limit and deadline (Compliance), so the scope remains aligned with the stated safety-focused intent."},"complexity_factors":["Narrow applicability: applies only to Bell 212 helicopters with specific part number P/N 412-040-785-101 (Applicability).","Single, clear action: mandatory retirement of the part (Requirement).","Definite compliance window: retire before 2,500 hours or within 100 hours after 2 Feb 1995, whichever is later (Compliance).","Reference material: cross-references FAA AD 94-18-09 and Bell ASB 212-93-83 Rev A for background and procedures (Note 1), adding a traceability requirement.","Exception noted: similar part P/N 412-040-785-103 is explicitly not limited by this AD (Note 2), so implementers must distinguish part numbers.","Limited discretion: little administrative discretion—action and deadlines are prescriptive, but operators decide replacement procurement and scheduling (Requirement/Compliance)."],"plain_english_summary":"This airworthiness directive requires operators of Bell 212 helicopters fitted with main transmission lower planetary spider P/N 412-040-785-101 to remove (retire) that part from service on a fixed timetable. Compliance requires retirement before 2,500 hours time-in-service or within 100 hours after 2 February 1995, whichever is later. The measure is intended to prevent in-service failures identified in manufacturer fatigue tests; the operator bears the cost and responsibility of replacing the retired item."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-212-54-main-transmission-lower-planetary-spider","history":"/api/acts/ad-bell-212-54-main-transmission-lower-planetary-spider/history","analysis":"/api/acts/ad-bell-212-54-main-transmission-lower-planetary-spider/analysis","conflicts":"/api/acts/ad-bell-212-54-main-transmission-lower-planetary-spider/conflicts","importantCases":"/api/acts/ad-bell-212-54-main-transmission-lower-planetary-spider/important-cases","documents":"/api/acts/ad-bell-212-54-main-transmission-lower-planetary-spider/documents"}}