{"id":"F2006B09858","name":"AD/F50/31 - Accessory Compartment Cable Covers","slug":"ad-f50-31-accessory-compartment-cable-covers","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54940,"registerId":"commonwealth-F2006B09858-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F50/31 - Accessory Compartment Cable Covers","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/F50/31 Accessory Compartment Cable Covers 2/90\n\nDM\n\nApplicability: F27 Mk50 with S/Nos 20103 through 20108 and 20110 through 20134, in post Fokker SB F50-27-010 configuration.\n\n \n\nRequirement: Action in accordance with Fokker SB F50-27-024.\n\n \n\nNote: Netherlands AD 89-99 refers.\n\n \n\nCompliance: Unless already accomplished - prior to 31 March 1990.\n\n \n\nBackground: Country of origin AD. Water draining from covers may splash onto control cables and freeze, causing control difficulty.\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-limited safety directive targeting a specific mechanical defect in specific aircraft. It has not expanded beyond its original purpose of mandating a manufacturer-recommended safety modification."},"complexity_factors":["Very short document (under 200 words)","Only 4 operative provisions: applicability, requirement, note, and compliance","Single cross-reference to Fokker Service Bulletin F50-27-024 (external technical document, not legislative cross-reference)","Simple conditional: 'Unless already accomplished' — one exception only","No defined terms section; all terms are standard aviation nomenclature","No nested logic or sub-paragraphs"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\nOrders owners and operators of certain Fokker F50 aeroplanes to carry out a specific safety fix. The problem is that water can drain from cable covers in the accessory compartment, splash onto control cables, and freeze — potentially causing the flight controls to jam or become difficult to operate.\n\n**Who it affects:**\n- **Aircraft:** Fokker F50 (also known as F27 Mk 50) with serial numbers 20103 through 20108, and 20110 through 20134\n- **Configuration:** Only those that have already been modified according to an earlier Fokker Service Bulletin (SB F50-27-010)\n- **Operators:** Airlines or owners flying these specific aircraft in Australia\n\n**What must be done:**\nFollow the instructions in **Fokker Service Bulletin F50-27-024** — a technical document from the manufacturer detailing the required inspection or modification.\n\n**Deadline:**\nThe fix must be completed before **31 March 1990** (unless already done).\n\n**Why it matters:**\nFrozen control cables could lead to loss of aircraft control. This AD ensures a known safety defect is fixed before it causes an accident.\n\n**Note:** This references a Dutch airworthiness directive (Netherlands AD 89-99), showing Australia adopted a safety measure from the aircraft's country of origin."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD as presented applies only to the expressly listed serial numbers in the post-Fokker SB F50-27-010 configuration and mandates the actions described in Fokker SB F50-27-024 to be completed by the specified date (\"Applicability\", \"Requirement\", \"Compliance\"). The text contains no indication that the AD’s scope has been amended or expanded from an earlier version; therefore there is no evidence in this source that the instrument’s scope changed from its original intent."},"complexity_factors":["Narrow applicability limited to specific aircraft serial numbers and a post-SB configuration (Applicability)","Requirement is a cross-reference to an external manufacturer service bulletin rather than detailed technical steps in the AD itself (Requirement)","Fixed and imminent compliance deadline creates time-pressure for affected operators (Compliance)","Technical maintenance work requires licensed maintenance providers and adherence to the manufacturer’s procedures (Requirement)","Regulatory linkage to an overseas (Netherlands) AD noted but no additional domestic variations (Note)"],"plain_english_summary":"What this instrument requires (mechanically)\n\n- It requires operators of certain Fokker F50 (F27 Mk 50) aeroplanes to carry out a specific maintenance action described in Fokker Service Bulletin F50-27-024 (\"Requirement\").\n- The requirement applies only to aeroplanes with serial numbers 20103–20108 and 20110–20134 that are in the post-Fokker SB F50-27-010 configuration (\"Applicability\").\n- If the work has not already been done, it must be completed before 31 March 1990 (\"Compliance\").\n\nWhy the rule exists (official rationale and how it works)\n\n- The stated safety concern is that water draining from certain accessory compartment covers can splash onto control cables and freeze, which may make the flight controls difficult to operate (\"Background\").\n- The AD implements the corrective work by mandating compliance with the manufacturer’s service bulletin, rather than prescribing a specific repair technique in the text of the AD (\"Requirement\").\n\nWho pays, who decides, and what changes in behaviour\n\n- Aircraft operators who own or operate the listed serial-numbered aeroplanes must arrange and pay for the work in accordance with the cited service bulletin (see \"Applicability\" and \"Requirement\").\n- Licensed maintenance organisations or certificated engineers must perform the work to the standards and methods specified in the service bulletin; CASA enforces the AD’s requirement (see \"Requirement\" and \"Compliance\").\n- The immediate behaviour change required of affected operators is to schedule and complete the mandated maintenance before the specified deadline, or show it was already done (\"Compliance\").\n\nImplementation, costs, incentives and trade-offs (practical considerations)\n\n- Compliance path: Operators must obtain and follow Fokker SB F50-27-024. The AD does not detail parts or labour rates; those are determined by the manufacturer’s bulletin and the maintenance provider (\"Requirement\").\n- Direct costs and time: Operators bear the cost of parts, labour and downtime required to carry out the SB. These constitute an opportunity cost while the aeroplane is unavailable (inferred from \"Requirement\" and \"Compliance\").\n- Who benefits and how concentrated: The safety improvement (reduced risk of frozen control cables) directly benefits crew, passengers and third parties for the affected serial numbers (\"Background\"). The benefit is concentrated on operators and users of the listed aeroplanes; the cost is borne by those same operators (Applicability/Compliance).\n- Market effects: The AD channels work to maintenance providers and the manufacturer through the service bulletin. Independent maintenance organisations can compete to perform the work provided they meet the technical standards in the SB and regulatory requirements (\"Requirement\").\n- Administrative and compliance burden: The AD cross-references an external technical document (the Fokker SB), so operators must obtain that document and apply its instructions. Enforcement occurs through the AD compliance mechanism and routine regulatory surveillance (\"Requirement\" and \"Compliance\").\n- Implementation risk and technical discretion: The AD leaves technical means to the manufacturer’s SB; therefore the main discretion is at the level of approved maintenance providers applying the SB. Regulatory discretion is limited to enforcing compliance with the AD and accepted maintenance standards (\"Requirement\").\n- Possible operational responses: Operators facing the cost or downtime might reschedule flights, consolidate maintenance visits, or, in theory, alter fleet deployment; the AD does not prescribe any fleet-management options (inferred from the compliance requirement).\n\nAdministrative linkages\n\n- The AD notes a related Netherlands airworthiness directive (Netherlands AD 89-99) as background/reference (\"Note\"). This indicates alignment with the country of origin’s regulatory action rather than imposing an independent alternate method in the AD.\n\nBottom-line (mechanical effect)\n\n- For the small set of Fokker F50 aeroplanes listed, the AD makes compliance with the manufacturer’s service bulletin mandatory by a fixed date to address a freezing-on-control-cables hazard. Operators pay for and arrange the work; maintenance providers execute it to the SB standard; the regulator enforces completion (see \"Applicability\", \"Requirement\", and \"Compliance\")."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f50-31-accessory-compartment-cable-covers","history":"/api/acts/ad-f50-31-accessory-compartment-cable-covers/history","analysis":"/api/acts/ad-f50-31-accessory-compartment-cable-covers/analysis","conflicts":"/api/acts/ad-f50-31-accessory-compartment-cable-covers/conflicts","importantCases":"/api/acts/ad-f50-31-accessory-compartment-cable-covers/important-cases","documents":"/api/acts/ad-f50-31-accessory-compartment-cable-covers/documents"}}