{"id":"F2006B11040","name":"AD/KITFOX/2 - Flaperon Mass Balance","slug":"ad-kitfox-2-flaperon-mass-balance","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56654,"registerId":"commonwealth-F2006B11040-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/KITFOX/2 - Flaperon Mass Balance","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)  Kitfox Series Aeroplanes\n\n \n\nAD/KITFOX/2 Flaperon Mass Balance 5/90\n\nApplicability: All models not fitted with mass balance system (WMB 40).\n\n \n\nRequirement:  Carry out installation of flaperons mass balance system (WMB 40) in accordance with wing construction section of Denney Aerocraft Company, Kitfox Assembly Manual, or other scheme approved by the Authority.\n\n \n\nCompliance: Prior to 30 June 1990.\n\n \n\nBackground:  Flutter has occurred in both overseas and local aircraft. The company has made standard the fitting of a flaperon mass balance system and provides a kit for retrofit to aircraft not so equipped.\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":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive addressing a specific technical issue (flutter in Kitfox aircraft). It has not expanded beyond its original purpose of mandating a specific hardware modification to prevent aerodynamic flutter."},"complexity_factors":["Very short document (approximately 150 words)","Only 4 operative sections: Applicability, Requirement, Compliance, and Background","No defined terms section","No cross-references to other legislation or regulations","Single, straightforward requirement with one alternative compliance path ('other scheme approved by the Authority')","Clear, fixed compliance deadline","Simple conditional logic: applies to 'all models not fitted with' a specific system"],"plain_english_summary":"This is an **Airworthiness Directive** (a mandatory safety order) issued by Australia's Civil Aviation Safety Authority for **Kitfox series aeroplanes** (light homebuilt/kit aircraft).\n\n**What it does:**\n- Requires owners of certain Kitfox aircraft to install a **mass balance system** on the flaperons (control surfaces that combine the functions of flaps and ailerons)\n- The mass balance system is identified as \"WMB 40\"\n\n**Who it affects:**\n- Owners and operators of **all Kitfox models** that were **not originally fitted** with the WMB 40 mass balance system\n\n**Why it matters:**\n- **Flutter** (a dangerous, potentially catastrophic vibration of aircraft control surfaces) had been occurring in Kitfox aircraft both in Australia and overseas\n- The manufacturer (Denney Aerocraft Company) made the mass balance system standard equipment and offered a retrofit kit\n- This directive made the retrofit **legally mandatory** rather than optional\n- Aircraft had to comply **before 30 June 1990**\n\n**What owners had to do:**\nInstall the mass balance system following the manufacturer's Assembly Manual, or get an alternative scheme approved by the aviation authority."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive requires retrofitting the WMB 40 mass balance to all Kitfox models not already equipped and sets a compliance deadline; that matches the stated corrective purpose (to address incidents of flutter) in the Background. There is no indication in the text that the directive’s geographic, technical, or obligations scope has been broadened or narrowed relative to that stated purpose."},"complexity_factors":["Narrow technical scope: applies only to Kitfox series aeroplanes lacking WMB 40 (Applicability).","Single clear action required: installation of a specified device following a named manual or Authority approval (Requirement).","Fixed compliance deadline creates a time constraint (Compliance).","Dependence on manufacturer's manual for installation details increases reliance on external technical documentation (Requirement).","Provision for Authority‑approved alternatives introduces administrative discretion and potential delay (Requirement).","Implicit enforcement and verification tasks for regulators and maintainers, though enforcement mechanism not detailed in the text."],"plain_english_summary":"Mandates owners/operators of Kitfox aircraft not fitted with the WMB 40 to install that flaperon mass‑balance system per the Denney Kitfox Assembly Manual—or an Authority‑approved alternative—by 30 June 1990. It affects aircraft owners, maintenance providers, and the kit supplier.\n\nThe rule aims to mitigate reported flaperon flutter; owners bear kit and installation costs and downtime, while the Civil Aviation Safety Authority may approve alternative installation schemes."}},"importantCases":[],"_links":{"self":"/api/acts/ad-kitfox-2-flaperon-mass-balance","history":"/api/acts/ad-kitfox-2-flaperon-mass-balance/history","analysis":"/api/acts/ad-kitfox-2-flaperon-mass-balance/analysis","conflicts":"/api/acts/ad-kitfox-2-flaperon-mass-balance/conflicts","importantCases":"/api/acts/ad-kitfox-2-flaperon-mass-balance/important-cases","documents":"/api/acts/ad-kitfox-2-flaperon-mass-balance/documents"}}