{"id":"F2006B09837","name":"AD/F50/12 - Engine Anti-Ice Control Unit","slug":"ad-f50-12-engine-anti-ice-control-unit","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54874,"registerId":"commonwealth-F2006B09837-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F50/12 - Engine Anti-Ice Control Unit","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/F50/12 Engine Anti-Ice Control Unit 3/89\n\nApplicability: F27 Mark 050 aircraft.\n\n \n\nRequirement: Replace engine anti-ice control units in accordance with the requirements of Fokker SB F50-30-003.\n\n \n\nNote: RLD AD BLA No. 88-105 refers.\n\n \n\nCompliance: Forthwith.\n\n \n\nBackground: Following a number of flight tests which revealed ice formation in the engine intake duct, the manufacturer has released a new anti-ice control unit which increases the protection of the intake duct against ice formation. Fokker SB F50-30-003 details the procedure for replacement of the anti-ice control 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","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive’s scope is narrowly confined to F27 Mark 050 aircraft and requires replacement of the engine anti-ice control unit according to the manufacturer’s Service Bulletin. The instrument does not expand its reach beyond that type or introduce additional obligations; it mandates the replacement and relies on the SB for technical detail (Applicability; Requirement). There is no text in the instrument indicating an alteration or expansion of scope beyond the stated applicability."},"complexity_factors":["Narrow applicability (only F27 Mark 050 aircraft) (Applicability)","Single defined technical action required (replace anti-ice control unit) (Requirement)","Mandatory immediate compliance increases logistical pressure (Compliance)","Reliance on an external document for technical steps (Fokker SB F50-30-003) adds administrative dependency (Requirement)","Cross-reference to another AD (RLD AD BLA No. 88-105) introduces a secondary trail to check (Note)","The AD does not specify cost, parts availability, or alternative methods, leaving those operational details to operators and maintenance providers (Requirement; Background)"],"plain_english_summary":"What this directive does\n\n- Requires the replacement of the engine anti-ice control unit(s) on certain Fokker F50 (F27 Mark 050) aeroplanes. (Requirement)\n- The replacement must be carried out following the procedure set out in the manufacturer’s Service Bulletin F50-30-003. (Requirement)\n- The directive applies only to F27 Mark 050 aircraft. (Applicability)\n- Compliance is required immediately (“Forthwith”). (Compliance)\n\nWhy the change was made (according to the source)\n\n- The manufacturer conducted flight tests that showed ice forming in the engine intake duct. The manufacturer released a new anti-ice control unit intended to increase protection of the intake duct against ice formation. The Service Bulletin F50-30-003 explains the replacement procedure. (Background)\n\nWho it affects and who pays\n\n- Aircraft owners and operators of F27 Mark 050 aeroplanes are directly affected. They must arrange and pay for the replacement and any associated labour or downtime. (Applicability; Requirement)\n- Maintenance organisations or engineers who carry out work to the Service Bulletin will be the parties performing the replacement under the operator’s instruction. (Requirement)\n\nWhat decisions are made and by whom\n\n- The Civil Aviation Safety Authority (via this Airworthiness Directive) mandates the action and the timetable for compliance. (This instrument)\n- Operators decide when and how to schedule the replacement (subject to the instruction that it be done forthwith) and which approved maintenance provider performs it. (Compliance; Requirement)\n\nPractical effects and implementation mechanics\n\n- The immediate practical effect is that affected aeroplanes must have the specified anti-ice control unit removed and replaced in accordance with the Fokker Service Bulletin. (Requirement)\n- The Service Bulletin contains the technical steps; the AD does not set those technical details itself but makes following the Service Bulletin mandatory. (Requirement)\n- The AD cross-references a previous notice (RLD AD BLA No. 88-105) but does not restate its content. (Note)\n\nCosts, incentives and trade-offs (source-grounded)\n\n- Benefit claimed by the source: increased protection against ice formation in the engine intake duct due to the new unit. (Background)\n- Costs borne by operators: purchase of replacement unit(s), labour, and aircraft downtime necessary to perform the replacement. The AD requires compliance “forthwith”, which increases the immediacy of those costs. (Requirement; Compliance)\n- Incentives: operators are required to act to restore compliance; maintenance providers may receive increased business performing replacements. (Requirement)\n\nCompliance burden and implementation risk\n\n- The AD imposes a single, defined maintenance action rather than a continuing monitoring obligation. The technical steps are delegated to the manufacturer’s Service Bulletin; correct implementation depends on following that bulletin. (Requirement)\n- Implementation risks are typical of retrofit work: availability of replacement units, scheduling downtime, and ensuring the replacement is performed to the SB instructions. The AD does not specify logistics, costs, or alternative compliance methods. (Requirement; Background)\n\nEffects on private enterprise and competition (source-grounded)\n\n- The directive creates immediate demand for parts and maintenance labour for affected aircraft. Independent maintenance organisations can perform the work provided they follow the Service Bulletin and meet any regulatory approvals required for maintenance actions. (Requirement)\n- The AD does not change ownership, operating rights, routes, or other commercial terms; it only mandates a technical replacement on the specified aircraft type. (Applicability; Requirement)\n\nReferences in the instrument\n\n- Requirement: replace units per Fokker SB F50-30-003. (Requirement)\n- Applicability: F27 Mark 050 aircraft. (Applicability)\n- Compliance: Forthwith. (Compliance)\n- Background: manufacturer flight tests, new unit released to increase intake protection. (Background)\n- Note: RLD AD BLA No. 88-105 is referenced. (Note)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific technical defect in a specific aircraft type. It has not expanded beyond its original purpose of mandating a hardware replacement to prevent engine icing."},"complexity_factors":["Very short document (approximately 150 words of substantive content)","Only one substantive requirement (replace the control unit)","Single applicability criterion (F27 Mark 050 aircraft)","No defined terms section","No cross-references to other legislation (only references a manufacturer service bulletin and a Dutch aviation authority document)","Simple unconditional directive structure: applicability → requirement → compliance deadline","No exceptions, exemptions, or conditional logic"],"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:**\nIt requires owners or operators of specific Fokker F50 aircraft to replace the **engine anti-ice control units** (devices that prevent ice buildup in the engine) with an improved version.\n\n**Who it affects:**\nAnyone who owns, operates, or maintains **Fokker F27 Mark 050 aircraft** (also known as Fokker F50 series planes).\n\n**Why it matters:**\nIce forming in engine intake ducts is dangerous — it can restrict airflow, reduce engine performance, or cause engine failure. Flight tests found the existing anti-ice units weren't providing enough protection. The manufacturer (Fokker) developed a better unit, and this directive makes installing it compulsory **immediately** (\"forthwith\" means right away, without delay).\n\n**Key details:**\n- **Compliance deadline:** Immediate (forthwith)\n- **How to comply:** Follow the manufacturer's Service Bulletin F50-30-003 for the replacement procedure\n- **Background:** The old units allowed ice to form during testing; the new units provide better protection"}},"importantCases":[],"_links":{"self":"/api/acts/ad-f50-12-engine-anti-ice-control-unit","history":"/api/acts/ad-f50-12-engine-anti-ice-control-unit/history","analysis":"/api/acts/ad-f50-12-engine-anti-ice-control-unit/analysis","conflicts":"/api/acts/ad-f50-12-engine-anti-ice-control-unit/conflicts","importantCases":"/api/acts/ad-f50-12-engine-anti-ice-control-unit/important-cases","documents":"/api/acts/ad-f50-12-engine-anti-ice-control-unit/documents"}}