{"id":"F2006B09905","name":"AD/F50/75 - Aft Fuselage Skin Joint","slug":"ad-f50-75-aft-fuselage-skin-joint","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":55091,"registerId":"commonwealth-F2006B09905-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F50/75 - Aft Fuselage Skin Joint","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/F50/75 Aft Fuselage Skin Joint 6/97\n\nApplicability: All Serial numbers F27 Mk 050.\n\n \n\nRequirement: Inspect in accordance with Fokker Service Bulletin F50-53-053.\n\n \n\nNote: Netherlands AD 1997-022(A) refers.\n\n \n\nCompliance: Before accumulating 10 000 flight cycles from new, or within 6 months after 22 May 1997, whichever occurs last.\n\n \n\nThis Airworthiness Directive becomes effective on 22 May 1997.\n\n \n\nBackground: Fatigue cracking has been discovered on the LH side of the fuselage between STA 15375 and STA 16275 following investigation of pressurisation problems. Such cracking could lead to an unsafe condition, and thus requires an inspection to detect any problem, and to take any necessary corrective action.\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, single-issue safety directive focused specifically on fuselage skin joint inspections for one aircraft type. It has not expanded beyond its original narrow safety purpose."},"complexity_factors":["Very short document (approximately 200 words)","Only 1 substantive requirement (inspect per Service Bulletin)","No defined terms section — uses standard aviation terminology","Single compliance condition with straightforward 'whichever occurs last' logic","No cross-references to other legislation beyond a reference to a Dutch AD and a Fokker Service Bulletin","No exceptions, exemptions, or nested conditional logic"],"plain_english_summary":"This CASA Airworthiness Directive requires owners/operators of Fokker F50 (F27 Mk 50) aeroplanes in Australia to inspect the aft fuselage skin joint for fatigue cracking, using the Fokker Service Bulletin procedures. It responds to discovered cracks after pressurisation issues that could create an unsafe condition. Compliance is due by the later of reaching 10,000 flight cycles or six months after 22 May 1997."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This directive imposes a new mandatory inspection requirement (see 'Requirement' and 'Compliance'). Operators and their maintenance providers bear inspection and repair costs and must follow the Fokker Service Bulletin for procedure; maintenance organisations decide on corrective action where cracking is detected. Compliance timing is explicitly set in the AD ('before accumulating 10 000 flight cycles from new, or within 6 months after 22 May 1997, whichever occurs last'), so the measure expands routine maintenance obligations for the affected fleet."},"complexity_factors":["Narrow applicability: single aircraft type and all serial numbers F27 Mk 050 simplifies scope.","Single mandated action: an inspection per an external Fokker Service Bulletin reduces procedural complexity.","Fixed compliance window: clear timing (before 10,000 flight cycles or within 6 months after 22 May 1997) lowers ambiguity.","Dependency on external document: requires access to and interpretation of Fokker Service Bulletin F50‑53‑053 (administrative burden).","Reference to foreign AD: Netherlands AD 1997‑022(A) adds cross‑jurisdictional traceability.","Unspecified corrective action: the AD mandates inspection but leaves repairs to maintenance judgement and the service bulletin, creating technical discretion and potential cost variance.","Operational impact: inspections and any repairs can cause aircraft downtime and direct costs to operators."],"plain_english_summary":"Requires a mandatory inspection of the aft fuselage skin joint on all Fokker F50 (F27 Mk 50) aeroplanes, to be carried out in accordance with Fokker Service Bulletin F50‑53‑053 before 10,000 flight cycles or within six months after 22 May 1997 (whichever is later). It affects operators and maintenance organisations because fatigue cracking was found on the left‑hand fuselage; the inspection detects cracks and, where found, triggers corrective repairs to maintain airworthiness."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f50-75-aft-fuselage-skin-joint","history":"/api/acts/ad-f50-75-aft-fuselage-skin-joint/history","analysis":"/api/acts/ad-f50-75-aft-fuselage-skin-joint/analysis","conflicts":"/api/acts/ad-f50-75-aft-fuselage-skin-joint/conflicts","importantCases":"/api/acts/ad-f50-75-aft-fuselage-skin-joint/important-cases","documents":"/api/acts/ad-f50-75-aft-fuselage-skin-joint/documents"}}