{"id":"F2006B04591","name":"AD/BELL 212/59 - Tail Rotor Yoke","slug":"ad-bell-212-59-tail-rotor-yoke","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44330,"registerId":"commonwealth-F2006B04591-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 212/59 - Tail Rotor Yoke","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 212/59 Tail Rotor Yoke 8/98 DM\n\nApplicability: Model 212 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 installed.\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) 212-96-100, Revision A, dated 18 May 1998, or ASB 212-96-101 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 an airworthy trunnion assembly, P/N 212-010-738-001. If any incident as described in Requirement 1 of this Directive occurs after 10 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 212-96- 100, 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 212-96-100, whichever is applicable.\n\nNote 3: FAA Priority Letter AD 98-11-15 refers.\n\nCompliance: 1. Before further flight after 10 June 1998.\n\n    2. Before 10 December 1998.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\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 10 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. The Model 205A-1 helicopter is similar in design to the Model 212 helicopter. 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 discrete, targeted safety directive addressing a specific mechanical failure mode identified through accident investigation. The scope remains tightly focused on tail rotor yoke integrity for Bell 212 helicopters with specific part numbers. No evidence of scope creep from original aviation safety purpose."},"complexity_factors":["Multiple part number variants with different compliance paths (three distinct P/N groups with different associated replacement parts)","Nested conditional logic: Requirement 1 triggers Requirement 2, but Requirement 2 has its own conditional sub-requirement (incident timing affects compliance deadline)","Cross-references to external documents (Bell Helicopter Service Bulletins ASB 212-96-100 Rev A and ASB 212-96-101) without reproducing their full content","Dual compliance deadlines (immediate for incident history, fixed date for all others)","Technical aviation terminology requiring domain knowledge (trunnion assembly, flapping stop, x-ray diffraction, vibro-etching)","Exception handling: Note 2 provides identification marking system for compliant parts"],"plain_english_summary":"This CASA Airworthiness Directive orders owners/operators of Bell 212 helicopters with tail-rotor yokes P/N 212-011-702, 212-010-704, or 212-010-744 to inspect maintenance history for any bending/stress and, if any is found, ground the helicopter until the yoke is replaced with a new unit or an X‑ray‑inspected/serviceable unit and related parts updated. The FAA issued a similar urgent AD after a fatal in‑flight yoke failure.\n\nThe AD also mandates recurring 25‑hour inspections and immediate checks after any event that could stress the yoke to prevent loss of tail control."},"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":5,"scope_assessment":{"changed":false,"description":"The directive mirrors the FAA Priority Letter AD noted in its Background and applies to Bell 212 helicopters with the listed yoke part numbers (Applicability; Background). It does not expand applicability beyond those P/Ns but specifies inspections, replacements and recurring checks tied to incident history and ASB procedures (Requirements 1–3; Compliance)."},"complexity_factors":["Multiple specific affected part numbers (Applicability) increasing identification and logistics burden","Conditional trigger based on historical incident review rather than universal action, requiring record checks (Requirement 1)","Choice between replacement with zero‑hour assembly or acceptance after technical x‑ray diffraction inspection per Bell ASBs (Requirement 2; ASB refs) creates procedural complexity","Different post‑replacement installation requirements depending on yoke P/N (install flapping stop or trunnion) (Requirement 2)","Detailed inspection and replacement instructions cross‑referenced to parts of Bell ASB 212‑96‑100/101 (Requirement 3) — reliance on external service documents","Short and staged compliance windows (before further flight after 10 June 1998; before 10 Dec 1998) and an immediate‑action element (Compliance)","Recurring inspection interval requirement (every ≤25 hours or after any incident) imposes ongoing operational burden (Compliance 3)","Cross‑reference to FAA Priority Letter AD and prior accident investigation increases regulatory coordination and evidentiary expectations (Notes/Background)"],"plain_english_summary":"**What it does:** Requires operators of Bell 212 helicopters fitted with specific tail‑rotor yoke part numbers to check aircraft and yoke records for any incidents that could have overstressed the yoke, and to remove and replace or have the yoke pass an x‑ray diffraction inspection; it also mandates inspection or replacement of the related trunnion or flapping‑stop parts.  \n\n**Who it affects and why it matters:** Owners, operators and maintenance organisations must carry out inspections, part replacements and recurring checks (every ≤25 flight hours or after incidents) to reduce the risk of in‑flight yoke failure (Requirements 1–3; Compliance)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-212-59-tail-rotor-yoke","history":"/api/acts/ad-bell-212-59-tail-rotor-yoke/history","analysis":"/api/acts/ad-bell-212-59-tail-rotor-yoke/analysis","conflicts":"/api/acts/ad-bell-212-59-tail-rotor-yoke/conflicts","importantCases":"/api/acts/ad-bell-212-59-tail-rotor-yoke/important-cases","documents":"/api/acts/ad-bell-212-59-tail-rotor-yoke/documents"}}