{"id":"F2006B09771","name":"AD/F28/33 - Auxiliary Power Unit Exhaust - Inspection","slug":"ad-f28-33-auxiliary-power-unit-exhaust-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54667,"registerId":"commonwealth-F2006B09771-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F28/33 - Auxiliary Power Unit Exhaust - Inspection","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/F28/33 Auxiliary Power Unit Exhaust - Inspection 7/76\n\nApplicability: All models with S/Nos. 11003 to 11101 and 11991 to 11993 unless SB F28/49-21 has been accomplished.\n\n \n\nDocument: 1. Fokker SB F28/49-24; or\n\n \n\n2. RLD AD A21/76.\n\n \n\nCompliance: As detailed in the requirement document.\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":3,"scope_assessment":{"changed":false,"description":"The instrument’s scope is limited to the enumerated Fokker F28 serial numbers and to the inspection requirement set out in the referenced documents, with an exemption if SB F28/49-21 has been accomplished. The text does not indicate any change from that original scope."},"complexity_factors":["Narrow, concrete applicability defined by serial numbers (low scope ambiguity). (Applicability)","Procedural detail is deferred to external documents (Fokker SB F28/49-24 or RLD AD A21/76), requiring operators to consult additional material. (Document; Compliance)","Conditional exemption if Service Bulletin F28/49-21 has been accomplished — adds one simple conditional branch to applicability. (Applicability)","The AD itself contains no inspection intervals or technical steps, increasing reliance on the referenced documents and thus administrative overhead. (Compliance)","Decision and execution responsibility sits with operators/maintenance organisations, not the AD issuer — straightforward but operationally dependent. (Applicability; Document)"],"plain_english_summary":"This directive requires inspection of the auxiliary power unit (APU) exhaust on specified Fokker F28 aeroplanes (serials 11003–11101 and 11991–11993), unless Service Bulletin F28/49-21 has already been done. Operators or their maintenance organisations must arrange and fund inspections and any corrective work, following the procedures and timing set out in the referenced Fokker service bulletin or RLD airworthiness directive. The measure aims to reduce APU-related faults and associated safety risk."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive focused specifically on APU exhaust inspection for a limited fleet of Fokker F28 aircraft. It has not expanded beyond its original narrow technical purpose."},"complexity_factors":["Very short document (approximately 150 words of substantive content)","Only 2 defined applicability criteria (serial number ranges and exemption condition)","Simple conditional logic: applies to all in range UNLESS specific service bulletin accomplished","No nested exceptions or cross-references to other legislation sections","Refers to external technical documents rather than containing detailed requirements internally","No interpretation section or defined terms"],"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 F28 series aircraft** to inspect the **Auxiliary Power Unit (APU) exhaust** system. The APU is a small engine at the back of the plane that provides power when the main engines are off.\n\n**Who it affects:**\n- All Fokker F28 aircraft with **serial numbers 11003 to 11101 and 11991 to 11993**\n- **Unless** the aircraft has already had a specific modification done (Service Bulletin F28/49-21)\n\n**What must be done:**\nOperators must follow the inspection instructions in either:\n- **Fokker Service Bulletin F28/49-24** (the manufacturer's technical notice), or\n- **RLD AD A21/76** (a Dutch aviation safety directive — RLD is the Netherlands aviation authority)\n\n**Why it matters:**\nAPU exhaust problems can cause fires, carbon monoxide leaks, or structural damage. This directive ensures potentially dangerous exhaust conditions are found and fixed before they cause accidents.\n\n**Compliance:**\nAircraft operators must complete the inspection according to the timeline and procedures set out in those reference documents."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f28-33-auxiliary-power-unit-exhaust-inspection","history":"/api/acts/ad-f28-33-auxiliary-power-unit-exhaust-inspection/history","analysis":"/api/acts/ad-f28-33-auxiliary-power-unit-exhaust-inspection/analysis","conflicts":"/api/acts/ad-f28-33-auxiliary-power-unit-exhaust-inspection/conflicts","importantCases":"/api/acts/ad-f28-33-auxiliary-power-unit-exhaust-inspection/important-cases","documents":"/api/acts/ad-f28-33-auxiliary-power-unit-exhaust-inspection/documents"}}