{"id":"F2018L00029","name":"AD/BN-2/63 Amdt 1 Nacelle Box Structure at Bottom Fitting of MLG","slug":"ad-bn-2-63-amdt-1-nacelle-box-structure-at-bottom-fitting-of-mlg","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":96662,"registerId":"commonwealth-F2018L00029-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Britten-Norman Aircraft BN-2 Series Aero","sectionType":"division","heading":"Britten-Norman Aircraft BN-2 Series Aeroplanes","content":"### Britten\\-Norman Aircraft BN-2 Series Aeroplanes\n\n| AD/BN-2/63 Amdt 1 | Nacelle Box Structure at Bottom Fitting of MLG | 1/2018 |\n| ----------------- | ---------------------------------------------- | ------ |\n\n| Applicability: | All models of Britten-Norman BN-2, BN-2A, BN-2B and BN-2T Islander aircraft.                                                                                                                                                                                                                                                                                                                                                                                           |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Inspect the Nacelle Box Structure in accordance with Britten-Norman Mandatory Service Bulletin BN2/SB.235 Issue 1 (the SB), as in force at the time of issue of this AD.2. Repair Nacelle box doubler and J-stiffeners.Note: UK CAA AD 011-10-97 refers.                                                                                                                                                                                                            |\n| Compliance:    | 1. Unless already accomplished, within 50 landings after 21 May 1998 or before further flight if there have been more than 50 landings. After the inspection, conduct an inspection in accordance with the SB:a. At 500 hour intervals if no cracks are found in the nacelle box structure;b. Every 50 landings if cracks are found which are less than 5mm in length.2. Before further flight if any cracks found are greater than 5mm in length.                     |\n|                | This AD commences on 19 January 2018.                                                                                                                                                                                                                                                                                                                                                                                                                                  |\n| Background:    | Some of the attachment bolts of the landing gear bottom fitting have been found in a threadbound condition, and AD/BN-2/61 was issued to address this problem. Threadbound bolts can cause play at the main landing gear bottom fitting and result in cracks in the nacelle box structure.Amendment 1 of this AD is issued to emphasise the need to comply with the repeat inspection requirements of UK CAA classified Mandatory Service Bulletin BN2/SB.235 Issue 1. |\n\n![](image.001.jpeg)\n\nDavid Punshon  \nDelegate of the Civil Aviation Safety Authority\n\n8 January 2018","sortOrder":0},{"sectionNumber":"AD/BN-2/63 Amdt 1","sectionType":"part","heading":"AD/BN-2/63 Amdt 1","content":"## AD/BN-2/63 Amdt 1","sortOrder":1},{"sectionNumber":"Nacelle Box Structure at Bottom Fitting ","sectionType":"part","heading":"Nacelle Box Structure at Bottom Fitting of MLG","content":"## Nacelle Box Structure at Bottom Fitting of MLG","sortOrder":2},{"sectionNumber":"1/2018","sectionType":"part","heading":"1/2018","content":"## 1/2018","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"Amendment 1 does not expand the set of affected aircraft or add new repair obligations. It 'emphasise[s] the need to comply with the repeat inspection requirements' of Mandatory Service Bulletin BN2/SB.235 (Background). The amendment clarifies and reinforces repeat inspection timing rather than changing applicability or creating new types of actions."},"complexity_factors":["Technical inspection and repair of primary structure (nacelle box doubler and J‑stiffeners) requiring specialist maintenance skills and parts (Requirement).","Conditional compliance schedule: initial inspection within 50 landings or before further flight if >50 landings; thereafter 500‑hour intervals if no cracks, or every 50 landings if cracks <5 mm; immediate grounding before further flight if cracks >5 mm (Compliance).","Cross‑reference to an external Mandatory Service Bulletin 'BN2/SB.235 Issue 1' 'as in force at the time of issue of this AD' — creates operational dependence on the SB content and any future revisions (Requirement).","Applicability covers multiple models (BN‑2, BN‑2A, BN‑2B, BN‑2T) so affects a dispersed set of owners/operators (Applicability).","Interplay with earlier safety actions: references AD/BN‑2/61 and UK CAA AD 011‑10‑97, implying a chain of related directives and prior mitigations to consider (Background & Requirement).","Compliance timing anomalies in the text (inspection window references 21 May 1998 alongside AD commencement 19 January 2018) create potential for interpretive or implementation questions (Compliance / AD commencement).","Administrative burden: operators must track landings and flight hours to meet different repeat‑inspection triggers, and carry cost and operational disruption for inspections, repairs and possible grounding (Compliance)."],"plain_english_summary":"This airworthiness directive requires operators of Britten‑Norman BN‑2 family aircraft to inspect the nacelle box structure at the main landing‑gear bottom fitting using Mandatory Service Bulletin BN2/SB.235 and to repair the nacelle box doubler and J‑stiffeners where required. Inspections must begin within 50 landings (or sooner) and then repeat at specified intervals depending on whether cracks are found. It affects aircraft owners/operators who must fund inspections, repairs and any grounding time."},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is an amendment (Amendment 1) to an existing Airworthiness Directive. The amendment does not expand the scope beyond the original intent — it remains focused on the nacelle box structure inspection requirements. The amendment merely clarifies and emphasises the need to comply with repeat inspection requirements from the referenced service bulletin. The applicability (affected aircraft models) and core safety purpose remain unchanged from the original AD/BN-2/63."},"complexity_factors":["Single specific technical subject matter (aircraft structural inspection)","Clear conditional logic with only two main branches (cracks found vs. no cracks found)","Limited cross-referencing (only references one UK CAA directive and one service bulletin)","Short document with straightforward compliance timeline","Some technical aviation terminology requires domain knowledge but is standard for the industry","No nested exceptions or complex definitional sections"],"plain_english_summary":"This AD mandates inspection and, if necessary, repair of the nacelle box structure around the main landing gear bottom fitting on Britten‑Norman Islander (BN‑2 series) aircraft. It responds to instances of threadbound or loose bolts that allow movement, vibration and cracking that could threaten structural integrity.\n\nIt affects all owners, operators and maintainers of these Islanders in Australia and requires prompt and recurring checks and repair of any cracked or damaged reinforcement parts to keep the aircraft airworthy."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bn-2-63-amdt-1-nacelle-box-structure-at-bottom-fitting-of-mlg","history":"/api/acts/ad-bn-2-63-amdt-1-nacelle-box-structure-at-bottom-fitting-of-mlg/history","analysis":"/api/acts/ad-bn-2-63-amdt-1-nacelle-box-structure-at-bottom-fitting-of-mlg/analysis","conflicts":"/api/acts/ad-bn-2-63-amdt-1-nacelle-box-structure-at-bottom-fitting-of-mlg/conflicts","importantCases":"/api/acts/ad-bn-2-63-amdt-1-nacelle-box-structure-at-bottom-fitting-of-mlg/important-cases","documents":"/api/acts/ad-bn-2-63-amdt-1-nacelle-box-structure-at-bottom-fitting-of-mlg/documents"}}