{"id":"F2006B10366","name":"AD/HILLER 12/41 - Tail Rotor Blades","slug":"ad-hiller-12-41-tail-rotor-blades","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115988,"registerId":"commonwealth-F2006B10366-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HILLER 12/41 - Tail Rotor Blades","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)  \nHiller UH-12 Series Helicopters\n\nAD/HILLER 12/41 Tail Rotor Blades 9/90 TX\n\nApplicability: All models UH-12E, UH-12E-L, UH-12L and UH-12L4 helicopters.\n\nRequirement: Visually inspect tail rotor blades P/N 55073 and remove from service tail rotor blade assemblies with serial numbers 3028, 3089, 9506, 9584, 9607, 10245, 10516, 10917,\n\n13278, 14715, 14898, 15073, 15285, 15978, 16114, 20918.\n\nUnairworthy blades found are to be permanently marked unserviceable and reported to the Authority.\n\nNote: FAA Telex AD 90-15-01 refers.\n\nCompliance: Unless already accomplished, prior to further flight after 19 July 1990.\n\nBackground: Country of origin AD. It has been found that records for certain life limited tail rotor blades have been falsified. Service life limits may have been exceeded, this could result in blade failure and loss of control of the helicopter.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope: addressing a specific safety defect in specific helicopter models with specific part serial numbers. There is no evidence of scope creep; it remains a targeted safety intervention."},"complexity_factors":["Very short document (under 200 words)","Only 4 defined elements: applicability (4 models), one part number, 16 specific serial numbers, and one compliance date","Single straightforward requirement with no conditional logic or exceptions","No cross-references to other legislation (only a note about related FAA document)","Clear, imperative language ('remove from service', 'permanently marked')","No nested definitions or interpretive provisions"],"plain_english_summary":"This is an **Airworthiness Directive** — essentially a mandatory safety order for aircraft owners and operators.\n\n**What it does:**\nThis directive requires owners of specific Hiller helicopter models (UH-12E, UH-12E-L, UH-12L, and UH-12L4) to immediately check their tail rotor blades. If the blades match certain serial numbers listed in the directive, they must be removed from service right away.\n\n**Why it matters:**\nSomeone had been **falsifying records** about how long these blades had been used. Aircraft parts have strict \"life limits\" — maximum flying hours before they must be replaced for safety. With fake records, blades that were too old and worn could still be flying. A failed tail rotor blade can cause a helicopter to crash.\n\n**Who must act:**\n- Owners and operators of the affected Hiller helicopter models\n- Maintenance engineers who work on these aircraft\n\n**What must be done:**\n- **Visual inspection** of tail rotor blades (part number 55073)\n- **Immediate removal** from service if serial numbers match: 3028, 3089, 9506, 9584, 9607, 10245, 10516, 10917, 13278, 14715, 14898, 15073, 15285, 15978, 16114, or 20918\n- **Permanent marking** of removed blades as \"unserviceable\"\n- **Reporting** to the Civil Aviation Safety Authority (CASA)\n\n**Deadline:**\nBefore the helicopter flies again after 19 July 1990 (or immediately if already past that date)."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The instrument sets out a targeted inspection and removal requirement for specified tail rotor blades on listed UH-12 models and names specific serial numbers (Applicability; Requirement). It does not expand beyond that stated scope, and the immediate compliance deadline and reporting obligation are consistent with the instrument's stated purpose (Compliance; Background)."},"complexity_factors":["Narrow applicability: only four UH-12 variants and a specific blade part number (Applicability; Requirement).","Explicit, short serial-number list of affected blade assemblies requiring straightforward comparison (Requirement).","Clear, immediate compliance deadline: inspection required before next flight after a fixed date (Compliance).","Simple, operationally direct actions: visual inspection, removal if affected, permanent marking and reporting (Requirement).","Reference to an external FAA telex for background/corroboration, adding minor cross-jurisdictional coordination (Note)."],"plain_english_summary":"This directive requires owners/operators of Hiller UH‑12E, UH‑12E‑L, UH‑12L and UH‑12L4 helicopters to visually inspect tail‑rotor blades (P/N 55073) and remove from service the listed serial‑numbered blades; any unairworthy blades must be permanently marked “unserviceable” and reported to the Authority.  \n\nCompliance is required before the next flight after 19 July 1990 — issued because falsified life‑limit records may have allowed blades to exceed safe service life."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hiller-12-41-tail-rotor-blades","history":"/api/acts/ad-hiller-12-41-tail-rotor-blades/history","analysis":"/api/acts/ad-hiller-12-41-tail-rotor-blades/analysis","conflicts":"/api/acts/ad-hiller-12-41-tail-rotor-blades/conflicts","importantCases":"/api/acts/ad-hiller-12-41-tail-rotor-blades/important-cases","documents":"/api/acts/ad-hiller-12-41-tail-rotor-blades/documents"}}