{"id":"F2006B04775","name":"AD/BN-2/63 - Nacelle Box Structure at Bottom Fitting of MLG","slug":"ad-bn-2-63-nacelle-box-structure-at-bottom-fitting-of-mlg","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44551,"registerId":"commonwealth-F2006B04775-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BN-2/63 - Nacelle Box Structure at Bottom Fitting of MLG","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-2/63 Nacelle Box Structure at Bottom Fitting of MLG 6/98\n\nApplicability: All Model BN-2, BN-2A, BN-2B, and BN2T Islanders.\n\n \n\nRequirement: Inspect in accordance with Pilatus Britten-Norman Mandatory Service Bulletin BN2/SB.235.\n\n \n\nCompliance: Unless already accomplished, within 50 landings after 21 May 1998.\n\n \n\nThis airworthiness directive becomes effective on 21 May 1998.\n\n \n\nBackground: Some of the attachment bolts of the main landing gear bottom fitting have been found in a threadbound condition, and AD/BN-2/61 was issued to address this problem.\n\nThreadbound bolts can cause play at the main landing gear bottom fitting and result in cracks in the nacelle box structure.\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\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1626},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive remains precisely focused on its original purpose: addressing the specific safety issue of cracks in the nacelle box structure caused by threadbound bolts in the main landing gear bottom fitting. It has not expanded beyond this singular technical safety mandate."},"complexity_factors":["Single, clearly defined inspection requirement","Reference to external technical document (Service Bulletin BN2/SB.235) for detailed procedures","Straightforward compliance metric (50 landings)","Limited applicability (four specific aircraft models only)","No nested conditions or exceptions"],"plain_english_summary":"This AD mandates a one-time safety inspection of the nacelle box bottom fitting where the main landing gear attaches on Pilatus Britten‑Norman Islander models BN‑2, BN‑2A, BN‑2B and BN2T, following Pilatus Britten‑Norman Mandatory Service Bulletin BN2/SB.235.  \n\nIt affects all operators of those Islander types because threadbound or loose landing‑gear bolts can cause play and cracking in the supporting structure, risking landing‑gear failure; the check was required within 50 landings after 21 May 1998."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bn-2-63-nacelle-box-structure-at-bottom-fitting-of-mlg","history":"/api/acts/ad-bn-2-63-nacelle-box-structure-at-bottom-fitting-of-mlg/history","analysis":"/api/acts/ad-bn-2-63-nacelle-box-structure-at-bottom-fitting-of-mlg/analysis","conflicts":"/api/acts/ad-bn-2-63-nacelle-box-structure-at-bottom-fitting-of-mlg/conflicts","importantCases":"/api/acts/ad-bn-2-63-nacelle-box-structure-at-bottom-fitting-of-mlg/important-cases","documents":"/api/acts/ad-bn-2-63-nacelle-box-structure-at-bottom-fitting-of-mlg/documents"}}