{"id":"F2006B04773","name":"AD/BN-2/61 Amdt 1 - Main Landing Gear Attachment Bolts","slug":"ad-bn-2-61-amdt-1-main-landing-gear-attachment-bolts","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44548,"registerId":"commonwealth-F2006B04773-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BN-2/61 Amdt 1 - Main Landing Gear Attachment Bolts","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)  \nPilatus Britten-Norman BN-2 Series Aeroplanes\n\nAD/BN-2/61\n\nAmdt 1\n\n  \nMain Landing Gear Attachment Bolts 6/98\n\nApplicability: Model BN-2, BN-2A, and BN-2B Series and BN-2T Islanders.\n\nRequirement: Action in accordance with Pilatus Britten-Norman Mandatory Service Bulletin BN- 2/SB.231 Issue 2.\n\nNote: UK CAA AD 008-10-96 refers.\n\nCompliance: Unless already accomplished, within 50 landings after 21 May 1998.\n\nThis amendment becomes effective on 21 May 1998.\n\nBackground: The action required by this Directive is to ensure that the bolts that attach the lower fitting of the main landing gear to the nacelle do not become thread bound. Due to skin thickness tolerances, bolts with only one washer installed can cause play to occur at the MLG bottom fitting. If play occurs in this area, it can cause cracks in the nacelle box structure.\n\nAmendment 1 is issued in response to Issue 2 of the Requirement document.\n\nThe original issue of this airworthiness directive became effective on 24 April 1997.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This amendment maintains the original scope — it simply updates the referenced service bulletin from Issue 1 to Issue 2. The core purpose (preventing thread-bound landing gear bolts and subsequent structural cracking) remains unchanged."},"complexity_factors":["Very short document (under 200 words)","Only 1 defined term implicitly referenced (the service bulletin)","Single compliance pathway with one condition (\"unless already accomplished\")","No cross-references to other legislation beyond a note about a UK equivalent","Clear, single-purpose safety mandate with straightforward applicability"],"plain_english_summary":"This safety order requires operators of Pilatus Britten‑Norman BN‑2 Islander aircraft to inspect and correct main landing‑gear attachment bolt installations per the manufacturer’s service bulletin (BN‑2/SB.231 Issue 2). Incorrect washer fitment can allow gear play that cracks the engine nacelle and risks structural failure. The corrective action must be done within 50 landings after 21 May 1998; the amendment updates the directive to reference Issue 2 of the bulletin."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Amendment 1 updates the Requirement document to Issue 2 of Pilatus Britten‑Norman Mandatory Service Bulletin BN‑2/SB.231. It does not expand the list of affected models or extend the compliance obligation beyond the original directive; rather it replaces the original requirement with the revised service bulletin. The original AD took effect 24 April 1997 and this amendment responds to the revised requirement document without broadening scope."},"complexity_factors":["Narrow technical scope: single component (main landing‑gear lower fitting bolts) and limited set of aircraft models.","Relies on an external mandatory service bulletin (BN‑2/SB.231 Issue 2) for the detailed corrective steps.","Short compliance window (50 landings) increases urgency for operators and maintenance providers.","Action requires hands‑on maintenance and possible parts (washers), imposing direct costs on owners/operators.","Cross‑references prior AD and a foreign authority (UK CAA AD 008‑10‑96), so implementers must track multiple documents for traceability.","Amendment updates the referenced Requirement document rather than creating new ongoing inspection regimes, reducing regulatory complexity."],"plain_english_summary":"Requires operators of Pilatus Britten‑Norman BN‑2 series aeroplanes (BN‑2, BN‑2A, BN‑2B and BN‑2T) to carry out the work set out in Mandatory Service Bulletin BN‑2/SB.231 Issue 2 so the bolts that attach the main landing‑gear lower fitting to the nacelle are fitted/adjusted to avoid thread binding. Compliance is required within 50 landings after 21 May 1998. The measure is intended to prevent play at the lower fitting that can cause cracks in the nacelle box structure, and the cost and work fall to aircraft owners/operators and their maintenance organisations."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bn-2-61-amdt-1-main-landing-gear-attachment-bolts","history":"/api/acts/ad-bn-2-61-amdt-1-main-landing-gear-attachment-bolts/history","analysis":"/api/acts/ad-bn-2-61-amdt-1-main-landing-gear-attachment-bolts/analysis","conflicts":"/api/acts/ad-bn-2-61-amdt-1-main-landing-gear-attachment-bolts/conflicts","importantCases":"/api/acts/ad-bn-2-61-amdt-1-main-landing-gear-attachment-bolts/important-cases","documents":"/api/acts/ad-bn-2-61-amdt-1-main-landing-gear-attachment-bolts/documents"}}