{"id":"F2006B09853","name":"AD/F50/27 - Windshield - Post Link Support Bracket- Forward Pressure Bulkhead","slug":"ad-f50-27-windshield-post-link-support-bracket-forward-pressure-bulkhead","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54926,"registerId":"commonwealth-F2006B09853-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F50/27 - Windshield - Post Link Support Bracket- Forward Pressure Bulkhead","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\n# AD/F50/27  Windshield - Post Link Support Bracket- Forward Pressure Bulkhead\n\nApplicability: Serial Numbers 20103 through 20108 and 20110 through 20135.\n\n# 13/89\n\n \n\nRequirement: Action in accordance with Fokker Service Bulletin F50-53-008, dated 26 July 1989.\n\n \n\nNote: RLD AD BLA 89-83 refers.\n\n \n\nCompliance: Prior to accumulating 20000 flight cycles.\n\n \n\nBackground: Cracking of the subject bracket was discovered during full-scale fatigue tests.\n\nSubstitution with an improved bracket is called for by this AD.\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":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD's scope, as recorded in the text provided, is limited to mandating substitution of the forward pressure bulkhead post link support bracket on the specifically listed serial-numbered aeroplanes and requires compliance before 20,000 flight cycles. The stated requirement aligns with the AD's background statement that cracking was found during fatigue tests and that substitution with an improved bracket is called for; there is nothing in the supplied text indicating the scope has been altered from that stated intent. (Applicability; Requirement; Background; Compliance)"},"complexity_factors":["Narrow applicability limited to a specific range of aircraft serial numbers (Applicability)","Single mandatory action: replace the specified bracket following a named service bulletin (Requirement)","Compliance measured against a single clear metric (flight cycles) with a single deadline (Compliance)","Dependence on an external technical document (Fokker Service Bulletin F50-53-008) which must be obtained and followed (Requirement)","Reference to another AD (RLD AD BLA 89-83) introduces a minor cross-reference for operators to consider (Note)"],"plain_english_summary":"### What this instrument requires\n\nThis Airworthiness Directive (AD) requires owners/operators of certain Fokker F50 (F27 Mk 50) aeroplanes to replace a specific windshield post link support bracket (the forward pressure bulkhead bracket) by following Fokker Service Bulletin F50-53-008, dated 26 July 1989. (Requirement; Service Bulletin citation)\n\nWhich aircraft are affected\n\n- The AD applies only to aeroplanes with serial numbers 20103 through 20108 and 20110 through 20135. (Applicability)\n\nWhen the work must be done\n\n- The required replacement must be completed before the affected aeroplane accumulates 20,000 flight cycles. (Compliance)\n\nWhy this action is mandated (source statement)\n\n- The AD notes that cracking of the specified bracket was discovered during full-scale fatigue tests and therefore mandates substitution with an improved bracket. (Background)\n\nWho decides and who pays\n\n- The Civil Aviation Safety Authority (CASA) requires the action by issuing this AD. The owners/operators of the listed aeroplanes are the parties responsible for carrying out the work and for arranging payment for parts and labour (the AD prescribes the required action but does not specify who pays). (Requirement; Applicability)\n\nHow the requirement is implemented in practice\n\n- Compliance is achieved by carrying out the procedures and modifications described in Fokker Service Bulletin F50-53-008 (the AD makes the service bulletin the mandatory instruction). Operators must obtain or access that service bulletin and follow it exactly to meet the AD. (Requirement)\n\nPractical effects, incentives and trade-offs (analytical lens)\n\n- Direct cost and resource impact: Operators of the listed serial-number aircraft will incur the direct costs of the replacement (parts, maintenance labour, and any aircraft downtime). The AD itself does not state those costs. (Requirement; Compliance)\n\n- Timing and operational impact: The compliance trigger is a flight-cycle limit (20,000 cycles). Operators must plan maintenance and scheduling so the replacement occurs before that threshold, which can shift maintenance timing and create opportunity costs for other work. (Compliance)\n\n- Technical implementation and discretion: The AD makes adherence to the Fokker service bulletin mandatory; interpretation of technical details and the actual execution will be done by the operator and the maintenance organisation performing the work in accordance with the bulletin. The AD does not set alternative means of compliance within the text provided. (Requirement)\n\n- Concentration of benefits and costs: The safety/airworthiness benefit (remedying the cracking identified in tests) is concentrated on the relatively small set of affected serial-number aircraft, while the cost falls directly and solely on their owners/operators. (Applicability; Background)\n\n- Cross-references and administrative links: The AD refers to another airworthiness directive (RLD AD BLA 89-83), indicating that operators should note related regulatory material; the AD does not itself reproduce the related directive. (Note)\n\nImplementation risks and uncertainties\n\n- The AD cites fatigue-test evidence of cracking as the reason for the mandatory replacement; the AD does not quantify the risk level, the expected service life after replacement, or the cost/time required for implementation. Operators must rely on the referenced service bulletin for the technical steps and on their maintenance suppliers for cost and scheduling estimates. (Background; Requirement)\n\nBottom line (mechanics first, then rationale)\n\n- Mechanics: If you operate an Fokker F50 with a serial number listed in this AD, you must replace the windshield post link support bracket per Fokker Service Bulletin F50-53-008 before the aeroplane reaches 20,000 flight cycles. (Applicability; Requirement; Compliance)\n\n- Rationale (as stated in the AD): The replacement is required because cracking of the bracket was found in full-scale fatigue tests, so the AD mandates substitution with an improved bracket. (Background)\n"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific structural defect discovered during fatigue testing. It has not expanded beyond its original purpose of mandating replacement of a single faulty bracket on specific aircraft."},"complexity_factors":["Single, specific mechanical component addressed (windshield post link support bracket)","Narrow applicability — only 32 specific aircraft serial numbers affected","Single compliance action required (follow one service bulletin)","Clear, unambiguous deadline (20,000 flight cycles)","No nested exceptions, conditional logic, or alternative compliance methods","Minimal cross-referencing (only one service bulletin and one reference to a Dutch aviation authority directive)","No defined terms section — uses plain technical language"],"plain_english_summary":"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:**\nOrders owners and operators of specific Fokker F50 aircraft to replace a faulty **windshield support bracket** (a metal part that helps hold the cockpit windshield in place) with an improved version.\n\n**Who it affects:**\nOwners and operators of Fokker F50 aircraft with **serial numbers 20103 through 20108 and 20110 through 20135** — approximately 32 aircraft in total.\n\n**Why it matters:**\nDuring fatigue testing (simulating years of takeoffs, landings, and pressurisation cycles), engineers found **cracks forming in this bracket**. If left unrepaired, a cracked bracket could compromise the structural integrity of the **forward pressure bulkhead** (the wall that separates the pressurised cockpit from the unpressurised nose section) and the windshield mounting. This creates risks of:\n- Windshield failure\n- Loss of cabin pressurisation\n- Potential decompression at altitude\n\n**What must be done:**\nOperators must follow **Fokker Service Bulletin F50-53-008** (dated 26 July 1989) and install the improved bracket **before the aircraft reaches 20,000 flight cycles** (roughly 20,000 takeoff-landing cycles).\n\n**Key point:** This isn't optional — it's a legal requirement under the Civil Aviation Regulations. Flying without compliance could ground the aircraft."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f50-27-windshield-post-link-support-bracket-forward-pressure-bulkhead","history":"/api/acts/ad-f50-27-windshield-post-link-support-bracket-forward-pressure-bulkhead/history","analysis":"/api/acts/ad-f50-27-windshield-post-link-support-bracket-forward-pressure-bulkhead/analysis","conflicts":"/api/acts/ad-f50-27-windshield-post-link-support-bracket-forward-pressure-bulkhead/conflicts","importantCases":"/api/acts/ad-f50-27-windshield-post-link-support-bracket-forward-pressure-bulkhead/important-cases","documents":"/api/acts/ad-f50-27-windshield-post-link-support-bracket-forward-pressure-bulkhead/documents"}}