{"id":"F2006B09748","name":"AD/F28/11 - Landing Gear - Mechanical Control Systems - Modification","slug":"ad-f28-11-landing-gear-mechanical-control-systems-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115954,"registerId":"commonwealth-F2006B09748-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F28/11 - Landing Gear - Mechanical Control Systems - Modification","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 F28 Series Aeroplanes\n\n \n\nAD/F28/11  Landing Gear - Mechanical NK Control Systems - Modification\n\nApplicability: All models with S/Nos. 11003 to 11024 and 11991 to 11993. Document:  Fokker SB F28/32-33 Para. 2, Parts II and III.\n\nCompliance: Before 30 April 1971.\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\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, time-bound airworthiness directive with a narrow, specific scope (particular serial numbers of one aircraft type). It has not expanded beyond its original purpose of mandating a specific landing gear modification."},"complexity_factors":["Extremely short document (under 150 words)","Only 4 defined elements: applicability (serial number ranges), document reference, compliance deadline, and subject matter","No cross-references to other legislation or regulations beyond the parent Civil Aviation Regulations 1998","No conditional logic, exceptions, or nested provisions","Single mandatory action with clear deadline and unambiguous technical reference (Fokker Service Bulletin)","Straightforward applicability test based on aircraft serial numbers"],"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) under the Civil Aviation Regulations 1998.\n\n**What it does:** It requires owners and operators of specific Fokker F28 series aircraft to modify the **mechanical control systems for the landing gear** (the machinery that lowers and locks the wheels for landing). The modification must follow instructions in **Fokker Service Bulletin F28/32-33, Parts II and III**.\n\n**Who it affects:** This applies only to specific aircraft serial numbers: **11003 to 11024 and 11991 to 11993** — a limited batch of early-production Fokker F28 planes.\n\n**Why it matters:** Landing gear failures are catastrophic. This directive addresses a known safety defect in the mechanical control systems before a specific deadline (**30 April 1971**), ensuring these aircraft cannot fly unless the fix is applied. It is now of historical interest only — the deadline passed over 50 years ago, and these aircraft are long retired from service.\n\n**Key takeaway:** A vintage safety mandate for a specific subset of Fokker F28 aircraft, requiring a mandatory landing gear modification by April 1971."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The instrument as presented is narrowly drawn and applies only to the stated serial numbers; it mandates a modification per the referenced Fokker service bulletin with a specific compliance date. The text contains no indication that the scope has been broadened or narrowed from any original intent within the document supplied."},"complexity_factors":["Short, specialised directive but relies on an external technical document (Fokker SB F28/32-33 Para. 2, Parts II and III) for implementation details","Narrow applicability defined by specific serial number ranges (requires accurate identification of affected airframes)","Historical compliance deadline (before 30 April 1971) — makes present applicability a matter of record rather than ongoing enforcement, but complicates retrospective compliance assessment","Regulatory cross-reference to Civil Aviation framework and Schedule of Airworthiness Directives (legal context must be understood to know enforcement mechanisms)","Lack of detail in the AD about who may perform the work, cost allocation, alternative compliance methods, or verification procedures increases operational uncertainty"],"plain_english_summary":"What this directive does, mechanically\n\n- This Airworthiness Directive (AD) requires a specific modification to the landing gear mechanical NK control systems on certain Fokker F28 series aeroplanes. The modification must follow the procedures in the referenced Fokker service bulletin (Fokker SB F28/32-33 Para. 2, Parts II and III) (Document: Fokker SB F28/32-33 Para. 2, Parts II and III).\n\nWho it affects\n\n- It applies only to Fokker F28 aeroplanes with serial numbers 11003 through 11024 and 11991 through 11993 (Applicability: All models with S/Nos. 11003 to 11024 and 11991 to 11993).\n- The directive is issued under the Commonwealth of Australia Civil Aviation framework and appears as part of the Civil Aviation Safety Authority's Schedule of Airworthiness Directives (COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES).\n\nWhen it must be done\n\n- The required modification had to be completed before 30 April 1971 (Compliance: Before 30 April 1971).\n\nWhy it matters (stated and implied purposes, and how to read them)\n\n- The AD mandates a modification by reference to the manufacturer's service bulletin. The expressed legal effect is to make that modification mandatory for the listed aeroplanes (Document reference; Applicability; Compliance).\n- The text of the AD itself does not set out the technical defect or incident that triggered the requirement; instead it points operators to the manufacturer's bulletin for the technical specification of the work (Document: Fokker SB F28/32-33 Para. 2, Parts II and III).\n\nWho pays and who decides\n\n- The issuing authority is the Commonwealth/Civil Aviation Safety Authority as the source of the AD (header). The AD obliges those responsible for the listed aeroplanes to carry out the modification by the stated date (Applicability; Compliance). Practically, the owner or operator of each affected aircraft will be the party required to ensure compliance; the AD does not set out funding arrangements.\n\nCompliance burden and implementation mechanics\n\n- Compliance requires operators to carry out the modification exactly as set out in the referenced Fokker service bulletin (Document reference). The AD does not provide parts, time estimates, or who may carry out the work; those specifics must be obtained from the service bulletin or other operational guidance.\n- The AD creates a discrete, time‑bounded compliance obligation limited to the listed serial numbers (Applicability; Compliance).\n\nIncentives, trade-offs and likely effects on private behaviour\n\n- The directive converts an element of the manufacturer's recommended work (the service bulletin) into a mandatory regulatory requirement for the identified aircraft. That shifts the legal risk of non‑compliance from optional practice to enforceable obligation (Document; Compliance).\n- Costs of compliance (parts, labour, aircraft downtime) fall on operators of the identified aeroplanes. Benefits from the modification (not described in the AD text) would in principle accrue to operators, crews and passengers of modified aircraft; the AD text does not quantify either costs or benefits.\n- Because the AD applies only to a specific and small set of serial numbers, costs are concentrated on those operators while any operational or safety benefits (as claimed by the manufacturer or regulator) are dispersed across users of those aircraft models.\n\nRisks, discretion and information gaps\n\n- The AD references an external technical document for the detailed work scope; interpreting and implementing the work depends on that external document (Document: Fokker SB F28/32-33 Para. 2, Parts II and III). The AD itself does not set out acceptance criteria, alternative methods of compliance, or enforcement mechanisms in the text provided.\n- The AD sets a compliance date but does not state monitoring, verification, or cost-support arrangements. Those implementation details, and any discretion to approve alternatives, are not included in the text provided.\n\nNet mechanical effect (short form)\n\n- Operators of the specifically listed Fokker F28 aeroplanes must modify the landing gear mechanical NK control systems in accordance with the referenced Fokker service bulletin, and must have done so by 30 April 1971 (Applicability; Document reference; Compliance)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f28-11-landing-gear-mechanical-control-systems-modification","history":"/api/acts/ad-f28-11-landing-gear-mechanical-control-systems-modification/history","analysis":"/api/acts/ad-f28-11-landing-gear-mechanical-control-systems-modification/analysis","conflicts":"/api/acts/ad-f28-11-landing-gear-mechanical-control-systems-modification/conflicts","importantCases":"/api/acts/ad-f28-11-landing-gear-mechanical-control-systems-modification/important-cases","documents":"/api/acts/ad-f28-11-landing-gear-mechanical-control-systems-modification/documents"}}