{"id":"F2006B09987","name":"AD/FU24/40 - Cockpit Ventilators - Modification","slug":"ad-fu24-40-cockpit-ventilators-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":55315,"registerId":"commonwealth-F2006B09987-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/FU24/40 - Cockpit Ventilators - Modification","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)  Airparts (NZ) Ltd. FU 24 Series Aeroplanes\n\n \n\nAD/FU24/40 Cockpit Ventilators - Modification 4/71\n\nApplicability: Model FU24-950 and other FU24 Series aeroplanes fitted with Mod. AP55 Part A with cockpit ventilators to Mod. AP23 or similarly located air intakes.\n\n \n\nRequirement: Seal off subject cockpit ventilators.\n\n \n\nCompliance: Within 50 hours time in service after 19 April 1971.\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\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive from 1971 addressing a specific mechanical modification on a specific aircraft type. There is no evidence of scope creep; it does exactly what it says on the tin — mandates sealing of cockpit ventilators — with no ancillary provisions or expanded regulatory reach."},"complexity_factors":["Single, unambiguous operative requirement ('Seal off subject cockpit ventilators')","No defined terms section","No cross-references to other legislation or regulations beyond the parent Civil Aviation Regulations 1998 citation","Simple applicability test based on aircraft model and modification status","Single, clear compliance deadline with objective trigger (50 hours time in service after fixed date)","No exceptions, exemptions, or conditional logic","Document length: approximately 150 words of substantive content"],"plain_english_summary":"**What this is:** An Airworthiness Directive (AD) — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA).\n\n**What it does:** Orders owners and operators of specific Fletcher FU24 aircraft to **permanently seal off certain cockpit air vents**.\n\n**Who it affects:** \n- Owners and operators of **FU24-950 model aircraft** and other FU24 series planes\n- Specifically those fitted with **Modification AP55 Part A** that have cockpit ventilators installed under **Modification AP23** (or similar air intake locations)\n\n**Why it matters:** These ventilators apparently posed a safety risk — likely allowing water ingress, foreign object damage, or interfering with cockpit pressurisation/ventilation systems in a dangerous way. Rather than repair or replace, the simplest safe solution was to seal them entirely.\n\n**The deadline:** Aircraft had to comply within **50 hours of flying time** after 19 April 1971.\n\n**In short:** If you owned one of these specific crop-duster style aircraft in 1971, you had about 50 flight hours to permanently block off these particular air vents or face regulatory non-compliance."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD's scope is stated directly in the instrument: it applies to Model FU24-950 and other FU24 series aeroplanes fitted with Mod. AP55 Part A with cockpit ventilators to Mod. AP23 or similarly located air intakes (Applicability). The requirement — to seal the subject cockpit ventilators — and the compliance deadline are explicit and self-contained in the text (Requirement; Compliance). The provided text contains no indication that the scope has been expanded or narrowed beyond this statement."},"complexity_factors":["Narrow and specific applicability limited to Model FU24-950 and FU24 series with specified modifications (Applicability).","Single, prescriptive required action: 'Seal off subject cockpit ventilators' (Requirement).","Short and explicit compliance timeframe: within 50 hours time in service after 19 April 1971 (Compliance).","No procedural detail provided about how to perform the sealing, leaving technical implementation choices to maintainers.","No exemptions, testing, verification or follow-up requirements stated in the text, which simplifies legal structure but increases technical judgment required.","Affects safety-critical aircraft systems (cockpit ventilation), which raises operational considerations despite simple wording."],"plain_english_summary":"This AD mandates sealing specified cockpit ventilators on Airparts (NZ) FU24 series aeroplanes (including FU24-950 and others fitted with Mod. AP55 Part A with ventilators routed to Mod. AP23 or similar intakes). It is mandatory for owners/operators and must be done within 50 hours time-in-service after 19 April 1971.\n\nOperators bear the cost and choose sealing methods (not specified); the change alters ventilation paths and may require engineering judgment and recordation for continuing airworthiness."}},"importantCases":[],"_links":{"self":"/api/acts/ad-fu24-40-cockpit-ventilators-modification","history":"/api/acts/ad-fu24-40-cockpit-ventilators-modification/history","analysis":"/api/acts/ad-fu24-40-cockpit-ventilators-modification/analysis","conflicts":"/api/acts/ad-fu24-40-cockpit-ventilators-modification/conflicts","importantCases":"/api/acts/ad-fu24-40-cockpit-ventilators-modification/important-cases","documents":"/api/acts/ad-fu24-40-cockpit-ventilators-modification/documents"}}