{"id":"F2006B04797","name":"AD/BN-2/9 Amdt 4 - Empennage - Inspection and Modification","slug":"ad-bn-2-9-amdt-4-empennage-inspection-and-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44584,"registerId":"commonwealth-F2006B04797-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BN-2/9 Amdt 4 - Empennage - Inspection and Modification","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Pilatus Britten-Norman BN-2 Series Aeroplanes\n\n \n\nAD/BN-2/9\n\nAmdt 4\n\n\nEmpennage - Inspection and Modification NK\n\n \n\nApplicability: All models.\n\n \n\nRequirement: 1. Modify the elevator trim tab installation in accordance with Britten Norman Modification Leaflet No. BN-2/NB/M/507.\n\n \n\n2.    Perform the inspections detailed in Britten Norman SB No. BN-2/SB49.\n\n \n\n3.    Perform the additional torque inspections detailed in Britten Norman SB No. BN- 2/SB49A.\n\n \n\nNote: The inspection detailed in para. 2 may be performed and certified by the pilot in command.\n\n \n\nCompliance: For para. 1 - Before 30 September 1971.\n\n \n\nFor para. 2 - At intervals not exceeding 50 hours time in service after 28 November 1975. For para. 3 - Within 5 hours time in service after 9 May 1974.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is Amendment 4 of an existing Airworthiness Directive. The scope remains tightly focused on empennage (tail section) safety for BN-2 aircraft. The amendment appears to add the third requirement (torque inspections per SB49A) and update compliance dates, but does not expand beyond the original safety purpose of ensuring empennage airworthiness."},"complexity_factors":["Very short document — only 3 substantive requirements plus compliance dates","No defined terms section — relies on external manufacturer documents (Service Bulletins and Modification Leaflets)","No conditional logic or nested exceptions","Simple, flat structure: Applicability → Requirement → Compliance","Cross-references are limited to three specific manufacturer documents, all explicitly named"],"plain_english_summary":"This CASA Airworthiness Directive targets Pilatus Britten‑Norman BN‑2 (Islander) aircraft in Australia, mandating a modification to elevator trim‑tab installation and recurring empennage inspections to address pitch‑control risks. It requires a one‑off trim‑tab change, 50‑hour tail inspections per SB BN‑2/SB49, and a bolt‑torque check within 5 flight hours per SB49A. Owners/operators must comply; the 50‑hour check may be signed off by the pilot‑in‑command."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This entry is Amendment 4 to AD/BN‑2/9 (Amdt 4). The instrument continues to require an elevator trim‑tab modification and inspections but explicitly adds the additional torque inspections (SB BN‑2/SB49A) and records the pilot‑in‑command certification allowance for para.2; those inclusions indicate scope adjustments from earlier versions of the AD (Requirement paras 1–3; Note to para.2; AD header)."},"complexity_factors":["Applicability to all BN‑2 models increases the population affected (Applicability).","Mandates follow‑up to three external Britten Norman documents (Modification Leaflet BN‑2/NB/M/507; SB BN‑2/SB49; SB BN‑2/SB49A) which operators must obtain and apply (Requirement paras 1–3).","Multiple, staggered compliance deadlines with historical time windows impose scheduling and recordkeeping demands (Compliance: modification by 30 Sept 1971; inspections every 50 hours after 28 Nov 1975; torque checks within 5 hours after 9 May 1974).","Permits pilot‑in‑command to perform and certify one category of inspection, creating mixed reliance on flightcrew versus maintenance personnel (Note to para.2).","Certification/recording obligations and potential need for specific tooling or technical skill to perform torque checks and modifications raise logistical/maintenance costs (Requirement paras 1–3).","Document is labelled an amendment (Amdt 4), indicating this AD has been revised rather than being a single, standalone issuance (AD header)."],"plain_english_summary":"This Airworthiness Directive requires all Pilatus Britten‑Norman BN‑2 aeroplanes to have the elevator trim‑tab installation modified and to undergo specified inspections and torque checks in accordance with Britten Norman technical leaflets and service bulletins. Owners/operators must pay for and schedule the work; paragraph 2 inspections may be performed and certified by the pilot‑in‑command. The instrument sets fixed compliance times (modification by 30 Sept 1971; recurring 50‑hour inspections after 28 Nov 1975; torque checks within 5 hours after 9 May 1974), creating recurring maintenance and certification obligations."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bn-2-9-amdt-4-empennage-inspection-and-modification","history":"/api/acts/ad-bn-2-9-amdt-4-empennage-inspection-and-modification/history","analysis":"/api/acts/ad-bn-2-9-amdt-4-empennage-inspection-and-modification/analysis","conflicts":"/api/acts/ad-bn-2-9-amdt-4-empennage-inspection-and-modification/conflicts","importantCases":"/api/acts/ad-bn-2-9-amdt-4-empennage-inspection-and-modification/important-cases","documents":"/api/acts/ad-bn-2-9-amdt-4-empennage-inspection-and-modification/documents"}}