{"id":"F2006B04787","name":"AD/BN-2/74 Amdt 1 - Engine Mounting Brackets","slug":"ad-bn-2-74-amdt-1-engine-mounting-brackets","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44570,"registerId":"commonwealth-F2006B04787-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BN-2/74 Amdt 1 - Engine Mounting Brackets","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Safety Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \n\nAIRWORTHINESS DIRECTIVE\n\n![](image.001.png)\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/BN-2/74 and issues the following AD under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)  \n\nPilatus Britten-Norman BN-2 Series Aeroplanes\n\nAD/BN-2/74\n\nAmdt 1\n\n  \nEngine Mounting Brackets 8/2003\n\nApplicability: All Model BN2A, BN2B, BN2T, BN2T-4R, and BN2T-4S Islander aircraft. Requirement: Inspect in accordance with B-N Group Ltd. Mandatory Service Bulletin (SB) No. 275\n\nIssue 3.\n\nNote: UK CAA AD 005-11-2001 refers.\n\nCompliance: At the next 500-hour inspection or SB 190 inspection after 21 March 2002, whichever occurs first. Repeat inspections/replace bracket(s) in accordance with criteria specified in the Compliance Statement of the Requirement document.\n\nThe initial compliance time remains unchanged by this issue. This Amendment becomes effective on 7 August 2003.\n\nBackground: There have been reports of extensive cracking of the engine mount brackets.\n\nManufacturer service bulletins SB 61 and SB 91 cover wear, cracking and corrosion of the engine mounting brackets, but not with cracks at the points described in the Requirement document.\n\nAmendment 1 is issued in response to the latest Requirement document, which changes crack tolerance/repeat inspection criteria.\n\n![](image.002.jpeg)  \n\nDavid Villiers\n\nDelegate of the Civil Aviation Safety Authority 18 June 2003\n\n![](image.001.png)\n\nThe above AD is notified in the Commonwealth of Australia Gazette on 16 July 2003.\n\n  \n\nPage 1 of 1","sortOrder":0}],"analysis":{"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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Applicability (which aircraft are covered) remains the same (Applicability), but the amendment modifies the technical compliance criteria by changing crack tolerance and repeat‑inspection requirements per the updated Requirement document (Background). The AD replaces the previous AD and keeps the initial compliance timing unchanged (Compliance; Background). Operators must follow the new SB No.275 Issue 3 criteria for inspections and remedial action (Requirement)."},"complexity_factors":["Applicability explicitly covers all Model BN2A, BN2B, BN2T, BN2T-4R, BN2T-4S Islander aircraft (Applicability).","Operational instructions are delegated to an external document: B-N Group Ltd. Mandatory Service Bulletin No.275 Issue 3 (Requirement), creating dependence on a technical SB for compliance detail.","Compliance timing is tied to flight‑hour/maintenance milestones: next 500‑hour inspection or SB 190 inspection after 21 March 2002, whichever occurs first (Compliance).","Repeat inspection and replacement criteria are set out in the SB’s Compliance Statement, so ongoing obligations depend on SB criteria and judgment calls during inspections (Compliance).","Amendment changes crack tolerance and repeat‑inspection criteria (Background), altering substantive technical thresholds rather than applicability.","AD revokes the prior AD (opening paragraph), requiring operators to shift to the new requirement set."],"plain_english_summary":"This directive requires operators of all Pilatus Britten‑Norman BN‑2 Islander variants to inspect engine mounting brackets and carry out repairs or replacements if the mandatory service bulletin (B‑N Group Ltd. SB No.275 Issue 3) indicates it. The first inspection is due at the next 500‑hour or SB 190 check after 21 March 2002, with repeat inspections or replacements as the bulletin’s compliance statement prescribes. CASA issued the amendment because reports found extensive cracking and the bulletin tightens crack tolerance and repeat‑inspection rules."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment remains tightly focused on its original purpose: addressing cracking in engine mounting brackets for specific Islander aircraft models. The amendment updates technical criteria (crack tolerance and repeat inspection intervals) based on new manufacturer data, but does not expand to cover additional aircraft types, components, or unrelated safety issues."},"complexity_factors":["Short, single-page document with clear structure (Applicability, Requirement, Compliance, Background)","Only 5 aircraft models specified in applicability section","Single primary action required (inspect per manufacturer bulletin)","Cross-reference to one UK CAA directive and two manufacturer service bulletins (SB 61, SB 91, SB 275)","Conditional compliance timing ('whichever occurs first' logic)","No defined terms section — uses plain language and references external technical documents","Simple amendment structure — revokes previous AD and replaces with updated criteria"],"plain_english_summary":"This safety notice replaces a prior AD and requires owners/operators of BN2A, BN2B, BN2T, BN2T-4R and BN2T-4S Pilatus Britten‑Norman Islanders to inspect engine mounting brackets per Manufacturer Service Bulletin No. 275 Issue 3, with the initial check due at the next 500‑hour service or the next specified inspection after 21 March 2002.\n\nIt mandates ongoing inspections and bracket replacement criteria from the bulletin because reports of serious mounting‑bracket cracking could lead to engine separation and catastrophic failure."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bn-2-74-amdt-1-engine-mounting-brackets","history":"/api/acts/ad-bn-2-74-amdt-1-engine-mounting-brackets/history","analysis":"/api/acts/ad-bn-2-74-amdt-1-engine-mounting-brackets/analysis","conflicts":"/api/acts/ad-bn-2-74-amdt-1-engine-mounting-brackets/conflicts","importantCases":"/api/acts/ad-bn-2-74-amdt-1-engine-mounting-brackets/important-cases","documents":"/api/acts/ad-bn-2-74-amdt-1-engine-mounting-brackets/documents"}}