{"id":"F2006B09866","name":"AD/F50/4 - Fire Sensing Element (Fire Wire) Bonding","slug":"ad-f50-4-fire-sensing-element-fire-wire-bonding","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54967,"registerId":"commonwealth-F2006B09866-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F50/4 - Fire Sensing Element (Fire Wire) Bonding","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/F50/4 Fire Sensing Element (Fire Wire) Bonding 1/89\n\nApplicability: All F27 MK 050 aircraft serial numbers 20103 to 20108, and 20110 to 20123 inclusive.\n\n \n\nRequirement: Action in accordance with Fokker SB F50-26-003.\n\n \n\nNote: Dutch AD BLA 88-46 also refers.\n\n \n\nCompliance: Prior to 26 February 1989.\n\n \n\nBackground:  Fokker have advised that undetected unserviceabilities of the fire sensing element (fire wire) can occur due to faulty bonding of the element.\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 limited to the listed Fokker F50 serial numbers and requires actions in accordance with a specified Fokker service bulletin by a set date. The text shows no indication that the scope has been expanded or narrowed relative to its stated objective of addressing faulty fire sensing element bonding; it remains targeted to the affected serial numbers and prescribes the manufacturer action (Applicability; Requirement; Compliance; Background)."},"complexity_factors":["Very narrow applicability: specific serial numbers (Applicability).","Single required action but the AD points to an external document (Fokker SB F50-26-003) for technical details (Requirement).","Fixed, near-term compliance deadline increases scheduling pressure (Compliance).","Technical work required (bonding/inspection) necessitates qualified maintenance personnel and potential parts, creating operational burdens.","Reference to a foreign AD (Dutch AD BLA 88-46) introduces a need for cross-referencing but does not add procedural steps within the AD itself (Note).","Regulatory source and mandatory nature are clear, so legal interpretation complexity is low (header information)."],"plain_english_summary":"### What this directive does (mechanical change)\n\n- Requires operators of certain Fokker F50 (F27 Mk 50) aeroplanes to carry out the maintenance action described in Fokker Service Bulletin F50-26-003. (Requirement)\n- The directive applies only to aircraft with serial numbers 20103 to 20108 and 20110 to 20123 inclusive. (Applicability)\n- The required action must be completed before 26 February 1989. (Compliance)\n\n### Why it was issued (stated purpose)\n\n- The background given is that Fokker advised there can be undetected faults in the fire sensing element (\"fire wire\") when its bonding is faulty. The AD references that advisory as the reason for mandating the maintenance action. (Background)\n- The AD also notes a related foreign airworthiness directive: Dutch AD BLA 88-46. (Note)\n\n### Who pays, who decides, and what changes in behaviour\n\n- Who pays: Owners/operators of the affected Fokker F50 aircraft will bear the direct costs (labour, parts, aircraft downtime) of complying with the service bulletin. (Applicability, Requirement, Compliance)\n- Who decides: The Civil Aviation Safety Authority issued this airworthiness directive under the Civil Aviation Regulations framework; it sets the mandatory compliance requirement. (header information)\n- What behaviour changes: Operators must obtain and implement the actions in Fokker SB F50-26-003 for each affected aircraft by the compliance date rather than rely on routine maintenance schedules alone. (Requirement, Compliance)\n\n### Practical effects, trade-offs and implementation notes\n\n- Compliance burden: The AD delegates technical detail to the Fokker service bulletin, so operators must obtain that SB and follow its procedures; this typically involves maintenance labour, possible replacement or re-bonding of the fire sensing element, inspection records and aircraft downtime. (Requirement)\n- Incentive structure: The AD replaces voluntary manufacturer advice with a mandatory requirement for the listed aircraft, creating a compliance obligation and removing operator discretion to defer the specific remediation described in the SB. (Requirement, Background)\n- Trade-offs and opportunity costs: Meeting the deadline requires allocating maintenance resources and scheduling aircraft out of service; those are direct costs to operators and may displace other maintenance tasks. (Compliance)\n- Implementation risk: The effectiveness of the AD depends on the technical adequacy of Fokker SB F50-26-003 and on correct execution by maintenance personnel. The AD itself does not provide technical steps; it prescribes compliance with the SB. (Requirement)\n- Cross-jurisdiction note: The AD points to a corresponding Dutch AD (BLA 88-46), which may be relevant for operators or maintenance organisations seeking additional context or equivalence. (Note)\n\n(Section citations: Applicability; Requirement; Compliance; Background; Note.)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive for a specific aircraft type and defect. It has not expanded beyond its original purpose of mandating a fire wire bonding inspection."},"complexity_factors":["Very short document (under 200 words)","Only 4 substantive paragraphs (Applicability, Requirement, Note, Compliance, Background)","Single technical reference to external document (Fokker SB F50-26-003)","No defined terms section","No conditional logic or nested exceptions","Simple, direct command structure: identify aircraft → do X by date Y"],"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 F50 aircraft to inspect and fix a problem with the **fire sensing element** (also called \"fire wire\") — a safety device that detects engine fires.\n\n**The problem:**\nThe fire wire can fail silently due to **faulty bonding** (poor electrical grounding/connection). If this happens, the crew won't get a warning if an actual fire occurs — a serious safety risk.\n\n**Who must act:**\nOwners of Fokker F50 aircraft with serial numbers 20103–20108 and 20110–20123 (18 aircraft total).\n\n**What they must do:**\nFollow the instructions in **Fokker Service Bulletin F50-26-003** — a technical repair notice from the manufacturer. The Dutch aviation authority issued a similar order (BLA 88-46), so this aligns with international safety standards.\n\n**Deadline:**\nBefore 26 February 1989.\n\n**Why it matters:**\nFire detection systems are critical for passenger and crew safety. This directive closes a gap where a broken fire wire could go unnoticed until it was too late."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f50-4-fire-sensing-element-fire-wire-bonding","history":"/api/acts/ad-f50-4-fire-sensing-element-fire-wire-bonding/history","analysis":"/api/acts/ad-f50-4-fire-sensing-element-fire-wire-bonding/analysis","conflicts":"/api/acts/ad-f50-4-fire-sensing-element-fire-wire-bonding/conflicts","importantCases":"/api/acts/ad-f50-4-fire-sensing-element-fire-wire-bonding/important-cases","documents":"/api/acts/ad-f50-4-fire-sensing-element-fire-wire-bonding/documents"}}