{"id":"F2006B04839","name":"AD/CA25/8 - Carburettor Heat Modification Number 7/97","slug":"ad-ca25-8-carburettor-heat-modification-number-7-97","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44640,"registerId":"commonwealth-F2006B04839-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CA25/8 - Carburettor Heat Modification Number 7/97","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nSkyfox Aviation (Hedaro) CA25 Series Aeroplanes\n\nAD/CA25/8 Carburettor Heat Modification Number 7/97 12/98 TX\n\nApplicability: All Skyfox CA25 and CA25N aircraft fitted with ROTAX 912 engines.\n\nRequirement: Embody Skyfox modification Number 7/97 in accordance with the manufacturer’s instructions.\n\nCompliance: Within 10 flying hours or 30 days, whichever is the sooner, of the effective date of this directive.\n\nThis directive becomes effective on 18 September 1998.\n\nBackground: ROTAX powered Skyfox CA25 and CA25N aircraft suffer from excessive RPM drop when carburettor heat is selected. Skyfox modification 7/97 was released in October 1997 to correct this unsatisfactory characteristic. This is considered to be a safety of flight issue and this Directive is issued to ensure that all Skyfox aircraft are modified expediently.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope: mandating a specific safety modification for a defined aircraft fleet. There is no evidence of scope creep or expansion beyond the original technical safety purpose."},"complexity_factors":["Single, unambiguous applicability clause covering specific aircraft models and engine type","One clear compliance action (install specific manufacturer modification)","Simple time-based compliance trigger (10 hours/30 days)","No defined terms section, no cross-references to other legislation, no conditional exceptions","Background provided in plain narrative form rather than technical regulatory language","Total length: approximately 150 words"],"plain_english_summary":"This is a **safety order** issued by Australia's aviation safety regulator (CASA) that requires owners of specific light aircraft to install a mechanical fix.\n\n**What it does:**\n- **Mandates a modification** to all Skyfox CA25 and CA25N aeroplanes that use ROTAX 912 engines\n- The fix involves installing \"Modification Number 7/97\" — a manufacturer-designed upgrade to the carburettor heat system\n\n**Why it matters:**\n- These aircraft were experiencing **dangerous engine power loss** (excessive RPM drop) when pilots activated carburettor heat\n- Carburettor heat prevents ice formation in the engine's fuel system; if it causes power loss instead, pilots may avoid using it, risking engine failure from ice — or use it and lose critical power during flight\n- This creates a genuine **flight safety risk**\n\n**Who must act:**\n- Owners/operators of affected Skyfox aircraft\n- Must complete the modification **within 10 flying hours or 30 days** (whichever comes first) from 18 September 1998\n\n**What happens if ignored:**\n- Operating the aircraft without this modification would violate civil aviation safety regulations, potentially grounding the aircraft and exposing the operator to enforcement action"},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"The manufacturer released modification Number 7/97 in October 1997 to correct an operational characteristic (Background). This directive makes that manufacturer modification mandatory for all applicable Skyfox CA25 and CA25N aeroplanes and sets a compliance deadline (Requirement; Compliance). In other words, the action moved from being a manufacturer-issued modification to a compulsory airworthiness directive with a specified timeframe for completion."},"complexity_factors":["Narrow applicability: only Skyfox CA25 and CA25N aircraft with ROTAX 912 engines (Applicability)","Single required action: embody one manufacturer modification (Requirement)","Short, specific compliance timeframe (10 flying hours or 30 days) (Compliance)","Technical detail delegated to manufacturer’s instructions rather than contained in the AD (Requirement)","Administrative need for proof of compliance and scheduling of maintenance (implied by Requirement and Compliance)"],"plain_english_summary":"Owners and operators of Skyfox CA25 and CA25N aeroplanes fitted with ROTAX 912 engines must have Skyfox modification 7/97 installed per the manufacturer’s instructions within 10 flying hours or 30 days of 18 September 1998. The mandatory change, at the owner’s expense and done by certificated maintenance, is intended to correct an excessive RPM drop when carburettor heat is selected."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ca25-8-carburettor-heat-modification-number-7-97","history":"/api/acts/ad-ca25-8-carburettor-heat-modification-number-7-97/history","analysis":"/api/acts/ad-ca25-8-carburettor-heat-modification-number-7-97/analysis","conflicts":"/api/acts/ad-ca25-8-carburettor-heat-modification-number-7-97/conflicts","importantCases":"/api/acts/ad-ca25-8-carburettor-heat-modification-number-7-97/important-cases","documents":"/api/acts/ad-ca25-8-carburettor-heat-modification-number-7-97/documents"}}