{"id":"F2006B04764","name":"AD/BN-2/52 Amdt 1 - Elevator Mass Balance Weights","slug":"ad-bn-2-52-amdt-1-elevator-mass-balance-weights","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44528,"registerId":"commonwealth-F2006B04764-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BN-2/52 Amdt 1 - Elevator Mass Balance Weights","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-2/52\n\nAmdt 1\n\n\nElevator Mass Balance Weights 5/89\n\n \n\nApplicability: All models that do not have modification NB/M/990 embodied. Requirement:  Action in accordance with Pilatus Britten-Norman SB BN2/SB113 Issue 3. Compliance:               Prior to the issue of the next Maintenance Release after 18 May 1989.\n\nBackground:  This amendment extends the applicability to aircraft manufactured after the issue of Issue 2 of the SB.\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\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"The amendment extends the AD’s applicability to include aircraft manufactured after the issue of Issue 2 of Pilatus Britten-Norman Service Bulletin BN2/SB113. The AD therefore increases the set of aircraft required to comply, while retaining an exemption for aircraft that already have modification NB/M/990 embodied. (Background; Applicability)"},"complexity_factors":["Short, narrowly targeted directive specifying a single manufacturer Service Bulletin (Requirement).","Clear exemption based on a single, identifiable modification (NB/M/990) (Applicability).","A single, explicit compliance deadline tied to the next Maintenance Release (Compliance).","Technical implementation details are external to the AD and reside in the referenced Service Bulletin (requires cross-reference).","Limited scope change noted in Background (expands applicability but does not add procedural complexity)."],"plain_english_summary":"Owners and operators of Pilatus Britten‑Norman BN‑2 series aeroplanes (except those with modification NB/M/990) must carry out the elevator mass‑balance work set out in Pilatus Britten‑Norman Service Bulletin BN2/SB113 Issue 3 before the next Maintenance Release after 18 May 1989. Issued by the Civil Aviation Safety Authority, the AD extends applicability to aircraft built after Issue 2 of the Bulletin and concentrates compliance, costs and scheduling on operators and approved maintenance providers."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a minor amendment that extends applicability to additional aircraft manufactured after the previous service bulletin issue. It does not represent scope creep beyond the original safety purpose of ensuring proper elevator mass balance weights on BN-2 aircraft."},"complexity_factors":["Single, specific aircraft type (Pilatus Britten-Norman BN-2 series)","Single technical requirement referencing one external document (Service Bulletin BN2/SB113 Issue 3)","Clear applicability test (absence of modification NB/M/990)","Simple compliance deadline tied to a standard aviation document (Maintenance Release)","No nested exceptions, conditional logic, or extensive defined terms","Background section provides only one sentence of context for the amendment"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). Think of it like a compulsory recall notice for aircraft.\n\n**What it does:** It requires owners and operators of **Pilatus Britten-Norman BN-2 series aeroplanes** (small twin-engine aircraft commonly used for regional transport and island hopping) to take specific maintenance action regarding **elevator mass balance weights**.\n\n**The technical bit explained:** The elevator is the part of the tail that makes the plane pitch up and down. \"Mass balance weights\" are counterweights built into this control surface to prevent dangerous vibrations (flutter) at high speeds. This AD mandates compliance with a specific manufacturer's service bulletin (SB BN2/SB113 Issue 3) to ensure these weights are correctly installed.\n\n**Who must act:** All BN-2 models **without** factory modification NB/M/990 already fitted.\n\n**The deadline:** Before the aircraft's next **Maintenance Release** (a certificate proving an aircraft is safe to fly) issued after **18 May 1989**.\n\n**Why this amendment matters:** This update (Amendment 1) expands the safety net. The original directive missed some newer aircraft; this version catches planes manufactured after the previous service bulletin was issued, ensuring no BN-2 slips through with potentially unsafe elevator weights."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bn-2-52-amdt-1-elevator-mass-balance-weights","history":"/api/acts/ad-bn-2-52-amdt-1-elevator-mass-balance-weights/history","analysis":"/api/acts/ad-bn-2-52-amdt-1-elevator-mass-balance-weights/analysis","conflicts":"/api/acts/ad-bn-2-52-amdt-1-elevator-mass-balance-weights/conflicts","importantCases":"/api/acts/ad-bn-2-52-amdt-1-elevator-mass-balance-weights/important-cases","documents":"/api/acts/ad-bn-2-52-amdt-1-elevator-mass-balance-weights/documents"}}