{"id":"F2006B09864","name":"AD/F50/38 - Auto Flight Idle Stop Mechanism Modification","slug":"ad-f50-38-auto-flight-idle-stop-mechanism-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54960,"registerId":"commonwealth-F2006B09864-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F50/38 - Auto Flight Idle Stop Mechanism 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 F50 (F27 Mk 50) Series Aeroplanes\n\n \n\nAD/F50/38 Auto Flight Idle Stop Mechanism Modification 10/90\n\nApplicability: Model F50 series with serial numbers 20103 through 20108, 20110 through 20159,\n\n20161 through 20173 and 20176 through 20178.\n\n \n\nRequirement: Action in accordance with Fokker Service Bulletin F50-76-008 Revision 1.\n\n \n\nNote: RLD AD 90-043 refers.\n\n \n\nCompliance: Prior to 1 January 1991.\n\n \n\nBackground: Reports have been received of incidents where the power levers could not be retarded below flight idle during landing. This Directive requires a modification of the mechanism adjustment of the auto flight idle stop located on the engine\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 safety directive addressing a specific mechanical defect in specific aircraft. It has not expanded beyond its original purpose of mandating a single modification to prevent power lever control issues during landing."},"complexity_factors":["Very short document (approximately 150 words of substantive content)","Only 4 defined elements: applicability (serial number ranges), requirement (single reference to service bulletin), compliance date, and background","No nested conditional logic or exceptions","Single cross-reference to external technical document (Fokker Service Bulletin)","No internal cross-references to other legislation or regulations","Straightforward command structure: 'Action in accordance with...'"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — essentially 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 modify the \"auto flight idle stop mechanism\" — a part of the engine control system that prevents pilots from accidentally pulling the power levers too far back during flight. The modification adjusts how this mechanism works.\n\n**Who it affects:** Only specific Fokker F50 aircraft with serial numbers in the ranges 20103–20108, 20110–20159, 20161–20173, and 20176–20178.\n\n**Why it matters:** There had been incidents where pilots couldn't reduce engine power below \"flight idle\" (a minimum power setting used during flight) when trying to land. This is dangerous because landing requires the ability to reduce power further. The directive fixes this safety problem by requiring a specific technical modification detailed in a Fokker Service Bulletin.\n\n**Key details:**\n- **Compliance deadline:** Before 1 January 1991\n- **How to comply:** Follow the instructions in Fokker Service Bulletin F50-76-008 Revision 1\n- **Related reference:** RLD AD 90-043 (a Dutch aviation safety directive on the same issue)"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD as published specifies a limited scope (the listed serial numbers) and a single mandatory action (modify the auto flight idle stop mechanism per the named service bulletin) with a set compliance date. The text contains no indication that the scope was broadened or narrowed from an earlier or original intent within this document itself."},"complexity_factors":["Narrow, serial-number-limited applicability (lists multiple serial ranges) (Applicability)","Mandatory compliance by a fixed date creates a scheduling constraint for operators (Compliance)","Technical work is prescribed by an external document (Fokker Service Bulletin F50-76-008 Rev 1), requiring cross-reference and access to that bulletin (Requirement)","Safety-critical subject matter (power levers and flight idle) increases the importance of correct technical execution but the AD itself does not provide procedural detail (Background; Requirement)","Reference to a related directive (RLD AD 90-043) introduces additional regulatory linkage to consider (Note)"],"plain_english_summary":"This AD mandates a mechanical adjustment to the auto flight idle stop on specified Fokker F50 (F27 Mk 50) serial numbers, to be done per Fokker Service Bulletin F50‑76‑008 Revision 1 and completed by 1 January 1991. It affects the listed owners/operators, who must arrange and pay for the work; the action responds to incidents where power levers could not be retarded below flight idle during landing."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f50-38-auto-flight-idle-stop-mechanism-modification","history":"/api/acts/ad-f50-38-auto-flight-idle-stop-mechanism-modification/history","analysis":"/api/acts/ad-f50-38-auto-flight-idle-stop-mechanism-modification/analysis","conflicts":"/api/acts/ad-f50-38-auto-flight-idle-stop-mechanism-modification/conflicts","importantCases":"/api/acts/ad-f50-38-auto-flight-idle-stop-mechanism-modification/important-cases","documents":"/api/acts/ad-f50-38-auto-flight-idle-stop-mechanism-modification/documents"}}