{"id":"F2006B09874","name":"AD/F50/47 - Nose Landing Gear Retraction Mechanism","slug":"ad-f50-47-nose-landing-gear-retraction-mechanism","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54989,"registerId":"commonwealth-F2006B09874-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F50/47 - Nose Landing Gear Retraction Mechanism","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/F50/47 Nose Landing Gear Retraction Mechanism 10/91\n\nApplicability: Serial number 20103 to 20108 inclusive, and 20110 to 20131 inclusive. Requirement:  Action in accordance with the Technical Requirements of RLD AD 90-057, dated\n\n23 May 1990.\n\n \n\nNote: Fokker Service Bulletin F50-32-004, dated 17 April 1990 refers.\n\n \n\nCompliance: Prior to exceeding 12 000 pressurisation cycles.\n\n \n\nBackground:  During full-scale fatigue testing, cracks were found near a lightening hole in the nose landing gear link assembly. To improve the fatigue life of this component, this AD calls for the replacement of the current retraction link assembly with a reinforced unit.\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 safety directive addressing a specific mechanical defect identified during testing. It has not expanded beyond its original purpose of mandating a single component replacement for a defined aircraft subset."},"complexity_factors":["Very short document (approximately 150 words)","Only 2 defined applicability criteria (serial number ranges)","Single compliance requirement with reference to external technical document (RLD AD 90-057)","No nested exceptions or conditional logic","No cross-references to other legislation beyond one referenced Service Bulletin","Straightforward cause-and-effect: crack found → part must be replaced"],"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 or operators of certain Fokker F50 aeroplanes to replace a part in the nose landing gear (the retraction link assembly) with a stronger, reinforced version.\n\n**Who it affects:** Only specific Fokker F50 aircraft with serial numbers 20103–20108 and 20110–20131. This is a small subset of the F50 fleet.\n\n**Why it matters:** During fatigue testing (simulating years of repeated takeoffs and landings), engineers found cracks developing near a hole in the original landing gear component. If left unaddressed, this could lead to landing gear failure — a serious safety risk. The directive prevents this by mandating the upgrade before the aircraft completes 12,000 pressurisation cycles (roughly, pressurising and depressurising the cabin during flights).\n\n**Key deadline:** The replacement must happen before the aircraft reaches 12,000 pressurisation cycles."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD applies to a defined subset of Fokker F50 serial numbers and mandates a single corrective action (replace the retraction link assembly with a reinforced unit) before 12,000 pressurisation cycles. The instrument does not broaden the fleet scope or add other operational restrictions beyond that replacement requirement; it relies on external technical requirements for the detailed method. (See \"Applicability\", \"Requirement\", and \"Compliance\".)"},"complexity_factors":["Narrow applicability limited to specific serial number ranges (20103–20108 and 20110–20131). (Applicability)","Mandatory action references external technical document (RLD AD 90‑057) rather than prescribing step‑by‑step procedures in the AD itself. (Requirement)","Reference to a manufacturer service bulletin for related information, creating dependency on another document. (Note)","Fixed operational deadline tied to a usage metric (12,000 pressurisation cycles) which requires tracking and scheduling by operators. (Compliance)","Clear single corrective measure (replacement with reinforced unit) limits technical ambiguity but requires parts and maintenance resources."],"plain_english_summary":"### What this instrument does, in plain terms\n\n- This Airworthiness Directive (AD) requires certain Fokker F50 (F27 Mk 50) aeroplanes to have their nose-gear retraction link assembly replaced with a reinforced unit. (See \"Requirement\" and \"Background\".)\n\n- The AD applies only to aircraft with serial numbers 20103–20108 and 20110–20131 inclusive. (See \"Applicability\".)\n\n- The replacement must be carried out in accordance with the Technical Requirements of RLD AD 90‑057 dated 23 May 1990, and the AD also refers to Fokker Service Bulletin F50‑32‑004 dated 17 April 1990 for related information. (See \"Requirement\" and \"Note\".)\n\n- The deadline is operational: the replacement must be done before the aircraft exceeds 12,000 pressurisation cycles. (See \"Compliance\".)\n\n### Why the AD was issued (official claim) and what it changes mechanically\n\n- The AD states its purpose is to improve the fatigue life of the nose landing gear retraction link assembly because full‑scale fatigue testing revealed cracks near a lightening hole in that component. (See \"Background\".)\n\n- Mechanically, the AD changes the aircraft by removing the existing retraction link assembly and installing a reinforced retraction link assembly specified in the referenced technical requirements. The technical details and methods are given by the referenced RLD AD and the Fokker service bulletin. (See \"Requirement\" and \"Note\".)\n\n### Who decides and who pays\n\n- The Civil Aviation Safety Authority issues the directive; compliance is required of owners/operators of the affected serial‑numbered aircraft. (See header and \"Applicability\".)\n\n- Practically, owners/operators will be responsible for arranging and paying for the replacement work (parts, labour, and any associated maintenance access) and for ensuring the work meets the referenced technical requirements. This follows from the AD’s mandatory replacement requirement and the compliance deadline. (See \"Requirement\" and \"Compliance\".)\n\n### Incentives, costs and trade-offs (mechanical/economic consequences)\n\n- Immediate costs for affected operators will include purchasing the reinforced assembly (or obtaining it through a maintenance facility), labour to remove and replace the link assembly, and aircraft downtime while the work is performed. (Inferred from the replacement requirement; see \"Requirement\" and \"Compliance\".)\n\n- The compliance deadline (before 12,000 pressurisation cycles) creates a scheduling constraint: operators must plan the replacement into maintenance programmes before reaching that cycle count. If the part or workshop capacity is limited, that may force earlier maintenance or rearrangement of aircraft utilisation. (See \"Compliance\".)\n\n- The AD’s reliance on an external technical document (RLD AD 90‑057) and a manufacturer service bulletin delegates the precise technical method and acceptance criteria to those documents. That concentrates technical discretion in the content of those referenced instruments rather than in the text of this AD. Operators must follow those external technical specifications to comply. (See \"Requirement\" and \"Note\".)\n\n### Compliance burden and implementation risk\n\n- Compliance burden is narrow in scope (specific serial numbers) but concrete: obtain the reinforced unit and carry out the replacement before the stated cycle limit. (See \"Applicability\" and \"Compliance\".)\n\n- Implementation risks that arise from the AD’s mechanics include potential part availability, the need to coordinate maintenance resources, and the operational impact of grounding an aircraft for the work. The AD does not describe funding, supply, or scheduling arrangements. (Implied by the replacement requirement and compliance timing; see \"Requirement\" and \"Compliance\".)\n\n### Net effect on private choice and operation\n\n- Operators of the listed aircraft must alter maintenance plans to install the reinforced link assembly by the deadline. Aside from that mandatory maintenance action, the AD does not change operational limits, crew procedures, or the airworthiness basis for aircraft outside the listed serial numbers. (See \"Applicability\" and \"Requirement\".)\n\nReferences to the instrument text: (Applicability), (Requirement), (Note), (Compliance), (Background)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f50-47-nose-landing-gear-retraction-mechanism","history":"/api/acts/ad-f50-47-nose-landing-gear-retraction-mechanism/history","analysis":"/api/acts/ad-f50-47-nose-landing-gear-retraction-mechanism/analysis","conflicts":"/api/acts/ad-f50-47-nose-landing-gear-retraction-mechanism/conflicts","importantCases":"/api/acts/ad-f50-47-nose-landing-gear-retraction-mechanism/important-cases","documents":"/api/acts/ad-f50-47-nose-landing-gear-retraction-mechanism/documents"}}