{"id":"F2006B07532","name":"AD/UH-1/4 - Tail Rotor Yoke","slug":"ad-uh-1-4-tail-rotor-yoke","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":50083,"registerId":"commonwealth-F2006B07532-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/UH-1/4 - 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 UH-1 Series Helicopters\n\nAD/UH-1/4 Tail Rotor Yoke 6/99 DM\n\nApplicability: Bell Helicopter Textron, Inc.-manufactured Model, UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and UH-1P helicopters.\n\nRequirement: Action in accordance with the technical requirements of FAA AD 99-07-15 Amdt 39- 11101.\n\nAccomplish the following in lieu of FAA AD 99-07-15 Paragraph (f), within the time stated in Paragraph (f):\n\nRevise the Operating Procedures and Manoeuvres Section of the Aircraft Flight Manual (AFM) to include the following additional procedures:\n\nTAIL ROTOR YOKE - PREFLIGHT VISUAL CHECK FOR STATIC STOP CONTACT DAMAGE (DEFORMED STATIC STOP OR TRUNNION YEILD INDICATOR).\n\nNote 1: Operators who use aircraft that have any of these affected yokes assemblies installed should use tail rotor tie downs when the aircraft is parked or stored.\n\nThis task may be performed by inserting a copy of this applicable Directive into the Operating and Procedures Section of the AFM.\n\nNote 2: The Requirement document was forwarded with the Direct Mail copy of this Directive.\n\nCompliance: As specified in the Requirement Document for the initial and repetitive inspection requirements; with a revised effective date of 5 May 1999.\n\nThis Airworthiness Directive becomes effective on 5 May 1999.\n\nBackground: The FAA issued the Requirement Document in response to in-flight failures of yokes installed on civilian and military helicopters of similar type design, including three reported accidents. The actions specified by this Directive are intended to detect static or dynamic overload on the yoke due to external bending forces, which could result in failure of the yoke, loss of the tail rotor, and subsequent loss of control of the helicopter.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This Directive substitutes the FAA AD 99‑07‑15 Paragraph (f) requirement with a mandatory AFM revision requiring a preflight visual check and tie‑down advice, while leaving the detailed initial and repetitive inspection requirements to the FAA Requirement Document. Net effect: scope shifted from the FAA paragraph to an AFM‑based procedural requirement plus reliance on the external Requirement Document for inspection specifics."},"complexity_factors":["Limited applicability: specific Bell UH‑1 models named (Applicability).","Action references external FAA Requirement Document for the technical inspection intervals and procedures (Requirement; Compliance).","Mechanism is administrative (AFM revision) rather than a mandatory physical modification, which lowers technical execution complexity but requires operator procedural change.","Repeated inspection obligations (initial and repetitive) increase ongoing compliance burden depending on the FAA document's intervals (Compliance).","Practical operator tasks: inserting directive into AFM, performing preflight visual checks, using tie‑downs and possible training, plus recordkeeping.","Dependence on another regulator's document (FAA AD 99‑07‑15) creates potential ambiguity if reconciling differences is required (Requirement).","Effective date and enforcement are fixed (becomes effective 5 May 1999), limiting discretionary timing (Compliance)."],"plain_english_summary":"This Directive requires operators of Bell UH‑1A/B/E/F/H/L/P helicopters to revise the Aircraft Flight Manual to add a preflight visual check for tail rotor yoke static‑stop contact damage and to advise use of tail‑rotor tie‑downs when parked. Inspections and timing are governed by the FAA Requirement Document referenced in the Directive. Operators pay for the manual change, inspections, tie‑downs and any training; the Directive replaces FAA AD paragraph (f) with this AFM‑based procedural requirement to detect yoke overload and prevent tail‑rotor loss."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard airworthiness directive implementing a specific safety measure for a defined aircraft component. It remains tightly scoped to tail rotor yoke inspections on UH-1 series helicopters, exactly as intended when the safety issue was identified."},"complexity_factors":["Very short document (under 300 words)","Only 7 defined helicopter models in applicability section","Single primary requirement with one modification from parent FAA directive","No nested exceptions or conditional logic — straightforward compliance timeline","Cross-reference to one external document (FAA AD 99-07-15) with explicit instruction to deviate from one paragraph only","Plain language background section explaining safety rationale"],"plain_english_summary":"This CASA Airworthiness Directive requires operators of specified Bell UH-1 series helicopters to add a preflight check of the tail-rotor yoke’s static stop to their Aircraft Flight Manuals and to use tail‑rotor tie‑downs when parked. It adopts an FAA safety action after accidents showed yoke damage can cause tail‑rotor loss and catastrophic loss of 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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-uh-1-4-tail-rotor-yoke","history":"/api/acts/ad-uh-1-4-tail-rotor-yoke/history","analysis":"/api/acts/ad-uh-1-4-tail-rotor-yoke/analysis","conflicts":"/api/acts/ad-uh-1-4-tail-rotor-yoke/conflicts","importantCases":"/api/acts/ad-uh-1-4-tail-rotor-yoke/important-cases","documents":"/api/acts/ad-uh-1-4-tail-rotor-yoke/documents"}}