{"id":"F2006B09857","name":"AD/F50/30 - Fuselage Upper Girder Connection at Frame Sta. 3415","slug":"ad-f50-30-fuselage-upper-girder-connection-at-frame-sta-3415","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54937,"registerId":"commonwealth-F2006B09857-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F50/30 - Fuselage Upper Girder Connection at Frame Sta. 3415","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/F50/30 Fuselage Upper Girder Connection at Frame Sta. 3415\n\n\n1/90\n\n \n\nApplicability: F27 Mark 50, serial numbers 20103 through to 20108, and 20110 through to 20147.\n\n \n\nRequirement:  Incorporate reinforcement modification in accordance with Fokker Service Bulletin F50-53-020 dated 15 September 1989.\n\n \n\nNote: RLD BLA 89-110 refers.\n\n \n\nCompliance: Prior to accumulating 10,000 flight cycles.\n\n \n\nBackground:  Full scale fatigue tests have determined that the connection angle between the upper girder of the flight compartment window and the upper torsion box of the passenger door has insufficient fatigue resistance. This AD introduces a reinforcement bracket to the area.\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":3,"scope_assessment":{"changed":false,"description":"The directive implements the stated original remedy for insufficient fatigue resistance by mandating a reinforcement bracket for the listed serial numbers before 10,000 flight cycles. The instrument’s applicability, required action and compliance threshold match the stated safety concern (Applicability; Requirement; Compliance; Background). No expansion or narrowing beyond that remedy is indicated in the text."},"complexity_factors":["Narrow technical scope: single structural reinforcement at a defined location and fleet subset (Applicability; Requirement).","Compliance measured in flight cycles requires operators to track life‑limits and schedule maintenance before 10,000 cycles (Compliance).","Reliance on manufacturer service bulletin for the modification specifies the engineering procedure and parts supply (Requirement).","Direct cost and downtime fall on aircraft owners/operators to obtain parts, perform modification and record compliance (Requirement; Compliance).","Regulatory enforcement and airworthiness record checks create administrative and inspection oversight (Applicability; Compliance).","Safety rationale grounded in full‑scale fatigue tests; technical judgment about fatigue life underpins the mandated fix (Background)."],"plain_english_summary":"This Airworthiness Directive requires operators of specified Fokker F27 Mk 50 (F50) aeroplanes (serial numbers 20103–20108 and 20110–20147) to install a reinforcement bracket at the fuselage upper girder connection at frame station 3415, following Fokker Service Bulletin F50‑53‑020 (15 Sept 1989). The regulator says the change fixes insufficient fatigue resistance found in full‑scale tests; installation must be completed before the aeroplane reaches 10,000 flight cycles."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific structural fatigue issue identified in testing. It has not expanded beyond its original purpose of mandating a single reinforcement modification for a defined aircraft subset."},"complexity_factors":["Single, specific applicability criterion (serial number ranges)","One straightforward requirement (install reinforcement per manufacturer bulletin)","Single compliance trigger (10,000 flight cycles)","No defined terms section","No cross-references to other legislation or complex conditional logic","Background explanation included in plain language","Extremely short document (under 200 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). Think of it as a \"recall notice\" for aircraft, but legally binding.\n\n**What it does:** It requires owners or operators of specific Fokker F50 aeroplanes to install a reinforcement bracket at a particular point on the fuselage (the main body of the plane). The problem is at \"Frame Station 3415\" — essentially a specific location where the window frame of the cockpit (flight compartment) connects to the door frame structure.\n\n**Why it matters:** Fatigue testing revealed this connection point could crack or fail over time due to repeated stress from flights (takeoffs, landings, pressurisation cycles). A failure here could compromise the structural integrity of the aircraft. The fix — adding a reinforcement bracket — prevents potential catastrophic damage.\n\n**Who must comply:** Only specific Fokker F50 aircraft with serial numbers 20103–20108 and 20110–20147. This is a small subset of the fleet.\n\n**When:** Before the aircraft completes 10,000 flight cycles (roughly, 10,000 pressurisation cycles — typically one per flight).\n\n**Key reference:** The work must follow Fokker Service Bulletin F50-53-020 (September 1989) — the manufacturer's official repair instructions."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f50-30-fuselage-upper-girder-connection-at-frame-sta-3415","history":"/api/acts/ad-f50-30-fuselage-upper-girder-connection-at-frame-sta-3415/history","analysis":"/api/acts/ad-f50-30-fuselage-upper-girder-connection-at-frame-sta-3415/analysis","conflicts":"/api/acts/ad-f50-30-fuselage-upper-girder-connection-at-frame-sta-3415/conflicts","importantCases":"/api/acts/ad-f50-30-fuselage-upper-girder-connection-at-frame-sta-3415/important-cases","documents":"/api/acts/ad-f50-30-fuselage-upper-girder-connection-at-frame-sta-3415/documents"}}