{"id":"F2006B04400","name":"AD/BELL 205/63 - Tail Rotor Yoke","slug":"ad-bell-205-63-tail-rotor-yoke","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44225,"registerId":"commonwealth-F2006B04400-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 205/63 - Tail 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 205 Series Helicopters\n\nAD/BELL 205/63 Tail Rotor Yoke 8/98 DM\n\nApplicability: Model 205A-1 helicopters with tail rotor yoke assembly, part number (P/N) 212-011- 702-all dash numbers, or P/N 212-010-704-all dash numbers, or P/N 212-010-744- all dash numbers, and model 205B helicopters with tail rotor yoke assembly, P/N 212- 011-702-all dash numbers.\n\nRequirement: 1. Review all historical records of the helicopter and the tail rotor yoke assembly for any static or dynamic incident history that could have imposed an excessive bending load on the yoke. If such a history exists, comply with Requirement 2 before further flight.\n\nNote 1: Examples of excessive bending loads include exposure to high wind gusts (such as those from rotor wash or prop blast), improper ground handling (in which the tail rotor blade has been used as a hand hold), improper feathering bearing removal (in which the yoke is not properly supported when pressing out bearings), a static ground strike of some type (such as being struck by a vehicle), or an incident in which a damaged tail rotor blade was replaced due to a blade strike. An overload may also occur dynamically during a power-on or power-off sudden stoppage incident or hard landing.\n\n    2. Remove the yoke assembly and replace it with a serviceable yoke assembly having zero hours time in service, or with a serviceable yoke assembly (regardless of time in service) that has passed an x-ray diffraction inspection in accordance with Bell Helicopter Textron, Inc. Alert Service Bulletin (ASB) 205-96-68, Revision A, dated 18 May 1998, or ASB 205-96-69 or ASB 205B-96-25, both dated 3 September 1996, whichever is applicable. When the yoke assembly is replaced, for helicopters with a yoke assembly, P/N 212-011-702-all dash numbers, install a serviceable tail rotor flapping stop, P/N 212-011-713-103, and for helicopters with yoke assemblies, P/N 212-010-704-all dash numbers or P/N 212-010-744-all dash numbers, install a serviceable trunnion assembly, P/N 212-010-738-001. If any incident as described in Requirement 1 of this Directive occurs after 3 June 1998 and before compliance with this requirement, then compliance with Requirement 2 is required before further flight.\n\nNote 2: Yoke assemblies that have passed an x-ray diffraction inspection at BHTI will have the letters FM vibro-etched on them following the serial number.\n\n    3. Inspect the trunnion assembly, and replace the yoke assembly and trunnion assembly, if required, in accordance with Part III, Paragraph 1, of ASB 205-96-68, Revision A; or inspect the tail rotor flapping stop and replace the yoke assembly and flapping stop, if required, in accordance with Part III, Paragraphs 1, 2, and 3, of ASB 205-96-69 or ASB 205B-96-25, whichever is applicable.\n\nNote 3: FAA Priority Letter AD 98-11-14 refers.\n\nCompliance: 1. Before further flight after 3 June 1998.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n    2. Before 3 December 1998.\n\n    3. After accomplishing the requirements of Requirement 2, thereafter at intervals not to exceed 25 hours time in service, or before further flight after any incident as described in Requirement 1.\n\nThis airworthiness directive becomes effective on 3 June 1998.\n\nBackground: This Directive reflects the issue of a Priority Letter AD by the FAA, which was prompted by an accident involving a BTHI Model 205A-1 helicopter in which the tail rotor yoke failed during flight. Investigation of the accident revealed that the tail rotor yoke assembly service life may be reduced due to unforeseen static and dynamic loading of the tail rotor. This condition, if not corrected, could lead to failure of the yoke, loss of the tail rotor, and subsequent loss of control of the helicopter.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This is a targeted safety directive addressing a specific mechanical failure risk identified after an accident. The scope remains focused on the original purpose: preventing tail rotor yoke failures in specific Bell 205 helicopter models through inspection and replacement requirements."},"complexity_factors":["Multiple specific part numbers with \"all dash numbers\" variations (P/N 212-011-702-all, P/N 212-010-704-all, P/N 212-010-744-all, P/N 212-011-713-103, P/N 212-010-738-001)","Cross-references to three different external Bell Helicopter service bulletins (ASB 205-96-68 Revision A, ASB 205-96-69, ASB 205B-96-25) with specific revision dates and paragraph references","Conditional logic: Requirement 2 only triggers if Requirement 1 finds incident history, but with an exception that any incident after 3 June 1998 triggers Requirement 2 regardless","Different replacement parts required depending on which yoke part number is installed (flapping stop vs trunnion assembly)","Three separate compliance deadlines with different triggers (before further flight after 3 June 1998; before 3 December 1998; recurring every 25 hours)","Reference to external FAA Priority Letter AD 98-11-14 for additional context"],"plain_english_summary":"This Airworthiness Directive orders owners/operators of certain Bell 205A-1 and 205B helicopters to inspect and, if necessary, replace the tail rotor yoke — including checking maintenance history for past shocks — and fit required associated parts, followed by recurrent inspections every 25 flight hours.  \n\nIssued after a fatal in‑flight yoke failure, it aims to detect hidden or impact damage that can cause premature yoke breakage and catastrophic loss of control."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"This AD stays within the original safety-corrective purpose described in the Background: to address the specific risk that unforeseen static or dynamic loads can reduce the tail rotor yoke's service life and cause in-flight failure. The directive does not expand regulatory scope beyond that corrective purpose; it mandates record review, conditional removal/replacement or nondestructive testing, installation of specified related parts, and recurring inspections directly related to the yoke failure risk identified. There is no addition of unrelated obligations or broadened applicability beyond the specified models and part numbers."},"complexity_factors":["Three-tiered requirement structure (Requirement 1: records check; Requirement 2: removal/replacement or x-ray inspection and parts installation; Requirement 3: inspection and recurring checks).","Multiple conditional triggers (actions depend on historical incident findings and on yoke P/N).","Several specific part numbers to match to required corrective parts (P/N 212-011-702-*, 212-010-704-*, 212-010-744-*, replacement parts P/N 212-011-713-103 and P/N 212-010-738-001).","Cross-references to three Bell Alert Service Bulletins and an FAA Priority Letter for procedural detail (ASB 205-96-68 Rev A; ASB 205-96-69; ASB 205B-96-25; FAA AD 98-11-14).","Recurring inspection interval that creates an ongoing compliance obligation (every 25 flight hours).","Identification requirement for inspected parts (vibro-etched \"FM\" marking) increases traceability steps.","Two distinct compliance deadlines (immediate before further flight for records check; before 3 December 1998 for replacement if triggered)."],"plain_english_summary":"**What this directive does (mechanics)\n\n- Applies to: Bell Helicopter Textron Model 205A-1 and 205B helicopters that have the specific tail rotor yoke part numbers listed (P/N 212-011-702-*, P/N 212-010-704-*, P/N 212-010-744-*). See \"Applicability.\" (AD/BELL 205/63)\n\n- Immediate record check (Requirement 1): Owners/operators must review the helicopter and yoke assembly maintenance and incident history for any event that could have imposed an excessive bending load on the yoke (examples given: exposure to strong gusts, improper ground handling, a static ground strike, sudden stoppage or hard landing, etc.). If any such incident is found, Requirement 2 must be done before the next flight.\n\n- Mandatory removal/repair/replacement (Requirement 2): If the record review shows a relevant incident (or as otherwise required), the yoke must be removed and replaced with either:\n  - a serviceable yoke assembly with zero hours time in service; or\n  - a serviceable yoke assembly (any hours) that has passed an x-ray diffraction inspection carried out to the Bell Alert Service Bulletin (ASB) procedures listed (ASB 205-96-68 Rev A, or ASB 205-96-69, or ASB 205B-96-25, as applicable).\n  When replacing the yoke, specific related parts must also be installed depending on the yoke P/N: for P/N 212-011-702-* install a tail rotor flapping stop P/N 212-011-713-103; for P/Ns 212-010-704-* or 212-010-744-* install trunnion assembly P/N 212-010-738-001. If an incident occurred after 3 June 1998 and before compliance, the replacement must be done before further flight.\n\n- Inspections and recurring checks (Requirement 3): Inspect the trunnion assembly (or flapping stop, depending on P/N) and, if required by the ASB procedures cited, replace the yoke and the trunnion/flapping stop. After completing Requirement 2, recurrent inspections are required at intervals not exceeding 25 flight hours, and also before further flight after any incident of the type described in Requirement 1.\n\n- Compliance deadlines: The record review must be done before further flight after 3 June 1998 (Requirement 1); the removal/replacement requirement must be completed before 3 December 1998 (Requirement 2); the recurrent inspections must be done every 25 hours thereafter or before further flight after any qualifying incident (Requirement 3).\n\n- Identification of inspected parts: Yokes that passed the x-ray diffraction inspection at Bell Helicopter Textron, Inc. (BHTI) will be marked with the letters \"FM\" vibro-etched after the serial number (Note 2).\n\nWhy the directive exists (stated purpose)\n\n- The AD follows an FAA Priority Letter prompted by an accident in which a Bell 205A-1 tail rotor yoke failed in flight. The stated safety concern is that unforeseen static and dynamic loads may reduce the service life of the yoke, possibly leading to yoke failure, loss of the tail rotor, and loss of control (Background).\n\nPractical effects, costs and who decides\n\n- Who pays: The helicopter owner/operator pays for the record review, inspections, removal and replacement of parts, x-ray diffraction inspections (if used), shipping and parts, and aircraft down-time.\n\n- Who decides and performs work: The operator must decide when to ground the helicopter and must arrange maintenance and inspection in accordance with the ASBs and the AD. Certified maintenance organisations and qualified inspectors must perform the work and the x-ray diffraction inspection according to the Bell ASBs.\n\n- Behaviour changes required of operators: maintain and review historical incident records (Requirement 1); remove and replace or get an x-ray-inspected yoke if the history shows a qualifying event (Requirement 2); fit specific auxiliary parts depending on the yoke P/N; perform recurring inspections every 25 hours (Requirement 3) and inspect before any further flight after a qualifying event.\n\nAssessment of incentives, trade-offs and implementation risks\n\n- Direct costs and downtime: Replacement with zero-hour assemblies or arranging x-ray inspections and related parts installation will generate immediate costs and aircraft downtime. The 25-hour recurring inspection interval imposes frequent maintenance costs and operational constraints.\n\n- Supply and service concentration: The AD references Bell ASBs and a specific BHTI x-ray inspection marking (FM). That creates demand for parts and inspections aligned with Bell/BHTI procedures; operators may be constrained to use authorised or suitably qualified facilities for the x-ray diffraction inspection and to source the specified parts.\n\n- Enforcement and safety trade-off: The AD forces conservative action (replace or inspect) where the record shows possible overload. That reduces the risk of in-flight failure at the cost of increased maintenance expense and aircraft unavailability. If parts are scarce or inspections backlogged, operators face grounding or restricted operations until compliance.\n\n- Substitution effects and opportunity cost: Some operators may retire aircraft, limit certain operations that raise overload risk, or increase inspection frequency beyond 25 hours to reduce perceived risk. Maintenance shops and authorised service centres capture concentrated demand for inspections and replacement parts; costs are broadly borne by operators (diffuse).\n\nSources and cross-references\n\n- The AD requires compliance with Bell Helicopter Textron ASBs (ASB 205-96-68 Rev A; ASB 205-96-69; ASB 205B-96-25) and references FAA Priority Letter AD 98-11-14 (Note 3). These ASBs contain the detailed inspection and replacement procedures that the AD makes mandatory."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-205-63-tail-rotor-yoke","history":"/api/acts/ad-bell-205-63-tail-rotor-yoke/history","analysis":"/api/acts/ad-bell-205-63-tail-rotor-yoke/analysis","conflicts":"/api/acts/ad-bell-205-63-tail-rotor-yoke/conflicts","importantCases":"/api/acts/ad-bell-205-63-tail-rotor-yoke/important-cases","documents":"/api/acts/ad-bell-205-63-tail-rotor-yoke/documents"}}