{"id":"F2006B10226","name":"AD/GAF-N22/9 - Fuel System Check Valves - Modification","slug":"ad-gaf-n22-9-fuel-system-check-valves-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":55884,"registerId":"commonwealth-F2006B10226-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/GAF-N22/9 - Fuel System Check Valves - 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)  GAF N22 and N24 Series Aeroplanes\n\n \n\nAD/GAF-N22/9 Fuel System Check Valves - Modification 4/76\n\nApplicability: Model N22 with S/Nos. N22-3 to N22-9 and N22-11 to N22-14. Document:  GAF SB No. N22.28.2.\n\nCompliance: Within 100 hours time in service after 16 April 1976.\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\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive's scope is confined to the explicitly listed GAF N22 serial numbers and requires the modification specified in the referenced service bulletin within the stated 100-hour compliance window. The AD text does not indicate any change or expansion of scope beyond that applicability and deadline."},"complexity_factors":["Narrow applicability limited to specific serial numbers (N22-3 to N22-9 and N22-11 to N22-14).","Technical method delegated to an external document (GAF SB No. N22.28.2) rather than detailed in the AD.","Single fixed compliance deadline expressed in hours time in service (100 hours after 16 April 1976).","No procedural alternatives, exemptions, or phased implementation detailed in the AD text.","Relies on accurate flight-hour tracking and access to the service bulletin, adding operational and information-access requirements."],"plain_english_summary":"CASA mandates modification of fuel-system check valves on specified GAF N22 aeroplanes (serials N22‑3–9, N22‑11–14) per GAF Service Bulletin No. N22.28.2. Owners/operators and maintenance organisations must complete the SB work within 100 hours TIS after 16 April 1976. It’s a safety-driven, operator-funded requirement that requires scheduling, parts, and recordkeeping to demonstrate compliance."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue safety directive from 1976 (as indicated by the '4/76' suffix). It addresses one specific mechanical defect in a limited production run of aircraft. There is no evidence of scope creep; it remains tightly focused on its original purpose of mandating a fuel system modification for safety reasons."},"complexity_factors":["Extremely short document (under 150 words)","Only 4 defined elements: applicability (specific serial numbers), document reference, compliance deadline, and the modification subject","No cross-references to other legislation or regulations beyond the parent Civil Aviation Regulations 1998","Single unconditional requirement with one simple time-based trigger (100 hours after fixed date)","No exceptions, exemptions, or conditional logic","Straightforward applicability test based on aircraft serial number ranges"],"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 GAF N22 aeroplanes to modify their fuel system check valves. A check valve is a one-way valve that stops fuel flowing backwards in the system — critical for preventing fuel leaks or engine failure.\n\n**Who it affects:** \n- **Specific aircraft only:** GAF N22 model aeroplanes with serial numbers N22-3 through N22-9, and N22-11 through N22-14\n- **Not affected:** Serial number N22-10 and N22-15 onwards (these are excluded)\n\n**What must be done:**\n- Follow the technical instructions in **GAF Service Bulletin No. N22.28.2** (the manufacturer's official repair notice)\n- Complete the modification within **100 hours of flying time** after 16 April 1976\n\n**Why it matters:** Faulty fuel check valves can allow fuel to flow the wrong way, potentially causing fuel starvation to the engine or fire hazards. This AD forces a fix before the problem causes an accident.\n\n**Key point:** This is not optional. Flying these specific aircraft without completing this modification violates civil aviation law."}},"importantCases":[],"_links":{"self":"/api/acts/ad-gaf-n22-9-fuel-system-check-valves-modification","history":"/api/acts/ad-gaf-n22-9-fuel-system-check-valves-modification/history","analysis":"/api/acts/ad-gaf-n22-9-fuel-system-check-valves-modification/analysis","conflicts":"/api/acts/ad-gaf-n22-9-fuel-system-check-valves-modification/conflicts","importantCases":"/api/acts/ad-gaf-n22-9-fuel-system-check-valves-modification/important-cases","documents":"/api/acts/ad-gaf-n22-9-fuel-system-check-valves-modification/documents"}}