{"id":"F2006B09680","name":"AD/F27/111 - Reduced Span Rudder Trim Tab","slug":"ad-f27-111-reduced-span-rudder-trim-tab","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115823,"registerId":"commonwealth-F2006B09680-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F27/111 - Reduced Span Rudder Trim Tab","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 F27 Series Aeroplanes\n\n \n\nAD/F27/111 Reduced Span Rudder Trim Tab 12/86\n\nApplicability: All model F27 with S/Nos. 10102 to 10684; 10686, 10687 and 10689 to 10692. Requirement:               Action in accordance with Fokker S.B. F27/55-62.\n\nNote: RLD BLA 86-53 refers.\n\n \n\nCompliance: Prior to 31 March 1988.\n\n \n\nBackground: This modification alleviates most of the problems associated with the previous design rudder trim tab.\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":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"Based on the text provided, the AD’s scope is to require the reduced-span rudder trim-tab modification on the listed Fokker F27 serial numbers and to direct compliance via Fokker Service Bulletin F27/55-62 by 31 March 1988. There is no material indication in the provided text that the scope was changed from this stated requirement."},"complexity_factors":["Single, narrowly-defined technical requirement: a specific modification to the rudder trim tab (Requirement; Background).","Clear applicability limited to named serial numbers, reducing scope ambiguity (Applicability).","Mandatory reliance on an external document (Fokker S.B. F27/55-62) for technical steps introduces a dependency on manufacturer documentation and its availability (Requirement).","Hard compliance deadline imposes scheduling and operational coordination for affected operators (Compliance).","No alternative compliance method or cost allocation specified, which concentrates discretion for technical implementation in the service bulletin rather than the AD text (Requirement)."],"plain_english_summary":"This Airworthiness Directive mandates a specific modification to the rudder trim tab on certain Fokker F27s, carried out exactly as Fokker Service Bulletin F27/55-62, to be completed by 31 March 1988. It affects owners/operators of the listed serial-numbered aircraft and the maintenance organisations that must perform and fund the work; the change is intended to remedy problems with the previous trim-tab design."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive with a single specific purpose. It has not expanded beyond its original intent of mandating a specific airframe modification for a defined aircraft population."},"complexity_factors":["Extremely short document (under 200 words)","Only 4 defined elements: applicability range, compliance date, technical reference (Fokker S.B.), and cross-reference","Single unconditional requirement with no exceptions or nested conditions","No internal cross-references or defined terms section","Straightforward command structure: identify aircraft → do this → by this date"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:**\nOrders owners and operators of specific Fokker F27 aircraft to modify the rudder trim tab (a small adjustable surface on the tail that helps keep the plane flying straight). The existing design had problems, so this directive requires installing a \"reduced span\" (shorter) version instead.\n\n**Who it affects:**\n- Owners and operators of Fokker F27 aircraft with serial numbers 10102 to 10684, plus 10686, 10687, and 10689 to 10692\n- This covers most F27 models in this serial number range\n\n**What must be done:**\n- Follow the technical instructions in **Fokker Service Bulletin F27/55-62** (the manufacturer's official repair/modification guide)\n- Complete the work **before 31 March 1988**\n\n**Why it matters:**\nThe old rudder trim tab design was causing operational problems. This modification fixes those issues, ensuring the aircraft handles properly and remains safe to fly. Ignoring this directive would make the aircraft non-compliant with Australian aviation safety regulations.\n\n**Cross-reference:** The Dutch aviation authority (RLD) issued a similar directive (BLA 86-53), showing this was an internationally recognised safety issue."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f27-111-reduced-span-rudder-trim-tab","history":"/api/acts/ad-f27-111-reduced-span-rudder-trim-tab/history","analysis":"/api/acts/ad-f27-111-reduced-span-rudder-trim-tab/analysis","conflicts":"/api/acts/ad-f27-111-reduced-span-rudder-trim-tab/conflicts","importantCases":"/api/acts/ad-f27-111-reduced-span-rudder-trim-tab/important-cases","documents":"/api/acts/ad-f27-111-reduced-span-rudder-trim-tab/documents"}}