{"id":"F2006B09870","name":"AD/F50/43 - Fuselage - Flight Compartment Window Frames -1","slug":"ad-f50-43-fuselage-flight-compartment-window-frames-1","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54979,"registerId":"commonwealth-F2006B09870-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F50/43 - Fuselage - Flight Compartment Window Frames -1","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)  Fokker F50 (F27 Mk 50) Series Aeroplanes\n\n \n\nAD/F50/43 Fuselage - Flight Compartment Window Frames -1 9/91\n\nApplicability: All F50 aircraft. Serial numbers 20103 to 20108 inclusive and 20110 to 20122 inclusive.\n\n \n\nRequirement: Action in accordance with the Technical Requirements of Netherlands AD BLA 89-98, dated 25 August 1989.\n\n \n\nCompliance: Prior to accumulating 10,000 pressurization cycles.\n\n \n\nBackground:  During full-scale fatigue tests of the forward fuselage test article, cracks occurred on the outside edges of the flight compartment window frames. These edges are sharp, which creates local stress concentrations. This AD calls for reworking of the outside edges of the flight-compartment window-frames to introduce a 0.5 mm radius.\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":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted airworthiness directive addressing a specific structural defect identified in fatigue testing. It has not expanded beyond its original purpose of mandating a preventive modification to cockpit window frames on a limited subset of Fokker F50 aircraft."},"complexity_factors":["Single, specific applicability clause covering only 19 aircraft serial numbers","One straightforward technical requirement referencing an external Netherlands AD (BLA 89-98)","Simple compliance deadline: prior to 10,000 pressurization cycles","No defined terms section, no cross-references to other legislation, no conditional logic or exceptions","Background explanation is plain English and technically concise","Total length is approximately 150 words of substantive content"],"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) for specific aircraft.\n\n**What it does:** It requires owners and operators of certain Fokker F50 aeroplanes to inspect and modify the window frames in the pilots' flight compartment (cockpit). Specifically, they must smooth out the sharp outer edges of these window frames by adding a small curved finish (a 0.5 mm radius) to prevent cracks from forming.\n\n**Who it affects:** Anyone who owns or operates Fokker F50 aircraft with serial numbers 20103–20108 and 20110–20122. This is a very specific, limited fleet.\n\n**Why it matters:** During fatigue testing (simulating years of pressurized flights), engineers found cracks developing at the sharp edges of cockpit window frames. Sharp edges concentrate stress, and under repeated pressurization cycles, this can lead to structural failure. This directive prevents potential catastrophic failure of the fuselage by requiring a simple smoothing modification before the aircraft reaches 10,000 pressurization cycles (roughly takeoff/landing cycles where the cabin is pressurized).\n\n**The bottom line:** If you fly or maintain one of these specific Fokker F50s, you must get the cockpit window edges smoothed out before the plane hits 10,000 pressurized flights. It's a preventive fix for a cracking problem discovered in testing."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"No — the directive implements the Netherlands AD BLA 89-98 by requiring rework of flight-compartment window-frame outside edges to a 0.5 mm radius and sets a single compliance threshold (prior to 10,000 pressurization cycles). The AD’s technical and temporal scope aligns with the source requirement; the only practical ambiguity is the phrasing of applicability."},"complexity_factors":["Narrow technical fix: single mechanical modification (0.5 mm radius) limits scope and implementation steps.","Clear compliance deadline tied to an easily tracked metric (10,000 pressurization cycles) — requires cycle tracking systems.","Applicability text contains potential ambiguity (says “All F50 aircraft” then lists specific serial numbers), increasing interpretive effort for operators and regulators.","Mandate references an external document (Netherlands AD BLA 89-98), so implementers must obtain and follow foreign technical requirements.","Administrative burden falls on operators to plan, fund and record the rework; minimal ongoing regulatory complexity after modification."],"plain_english_summary":"This airworthiness directive requires reworking the outside edges of the flight-compartment window frames on specified Fokker F50 aircraft so the edge has a 0.5 mm radius, reducing the sharp edge that caused cracks in fatigue tests. Operators of the listed serial numbers must complete that modification before the aeroplane accumulates 10,000 pressurization cycles (Compliance; Netherlands AD BLA 89-98). The operator pays and schedules the work as a mandatory maintenance action."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f50-43-fuselage-flight-compartment-window-frames-1","history":"/api/acts/ad-f50-43-fuselage-flight-compartment-window-frames-1/history","analysis":"/api/acts/ad-f50-43-fuselage-flight-compartment-window-frames-1/analysis","conflicts":"/api/acts/ad-f50-43-fuselage-flight-compartment-window-frames-1/conflicts","importantCases":"/api/acts/ad-f50-43-fuselage-flight-compartment-window-frames-1/important-cases","documents":"/api/acts/ad-f50-43-fuselage-flight-compartment-window-frames-1/documents"}}