{"id":"F2006B09872","name":"AD/F50/45 - Fuselage Power Supply Box Surround Structure","slug":"ad-f50-45-fuselage-power-supply-box-surround-structure","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54983,"registerId":"commonwealth-F2006B09872-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F50/45 - Fuselage Power Supply Box Surround Structure","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/F50/45 Fuselage Power Supply Box Surround Structure 10/91\n\nApplicability: Serial numbers 20103 to 20108 inclusive and 20110 to 20131 inclusive. Requirement:               Action in accordance with the Technical Requirements of RLD AD 89-130, dated\n\n27 October 1989.\n\n \n\nNote: Fokker Service Bulletin F50-53-024, dated 25 October 1989 refers.\n\n \n\nCompliance: Prior to exceeding 15 000 pressurisation cycles.\n\n \n\nBackground:  During full-scale fatigue testing, cracks occurred in the aircraft skin near the door hinge of the external power supply box. To improve the fatigue life of the skin in this area this AD calls for the installation of a reinforcement plate.\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":3,"scope_assessment":{"changed":false,"description":"The instrument sets a narrowly targeted requirement consistent with the stated safety finding: it applies only to the listed serial numbers and mandates the reinforcement per RLD AD 89‑130, with no text indicating an expansion or restriction beyond that original technical remedy."},"complexity_factors":["Narrow, serial-numbered applicability (serials 20103–20108 and 20110–20131) increases administrative tracking","Cross-reference to another authority document (RLD AD 89-130) creates reliance on external technical requirements","Reference to Fokker Service Bulletin F50-53-024 for technical detail means implementers must obtain and follow manufacturer guidance","Compliance metric is operational (pressurisation cycles: prior to exceeding 15,000) requiring record-keeping of cycle counts","Requires a structural modification (installation of a reinforcement plate) which entails maintenance planning, parts and certified workmanship","Limited text leaves technical discretion to the referenced documents and maintenance organisations rather than specifying step-by-step actions in this AD"],"plain_english_summary":"This airworthiness directive requires operators of Fokker F50 (F27 Mk 50) aeroplanes with serial numbers 20103–20108 and 20110–20131 to install a reinforcement plate around the external power supply box door hinge, following the Technical Requirements of RLD AD 89‑130 and Fokker Service Bulletin F50‑53‑024. Compliance must be completed before the airframe exceeds 15,000 pressurisation cycles. The directive responds to fatigue-test evidence of cracking in the skin near that hinge and places the modification and compliance burden on affected aircraft operators."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific structural fatigue issue identified during testing. It has not expanded beyond its original purpose of mandating a reinforcement modification for a defined fleet subset."},"complexity_factors":["Single, specific technical requirement (install reinforcement plate per Dutch aviation authority directive RLD AD 89-130)","Limited applicability (only 28 specific aircraft serial numbers)","Clear compliance deadline (15,000 pressurisation cycles)","No defined terms section, no cross-references to other legislation beyond the referenced Dutch AD and Fokker Service Bulletin","Straightforward background explanation with single causal chain (fatigue testing → cracks → reinforcement required)"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific Fokker F50 aircraft.\n\n**What it requires:** Owners or operators of certain Fokker F50 planes (specific serial numbers from 20103-20108 and 20110-20131) must install a reinforcement plate on the fuselage near the external power supply box door hinge. This must be done before the aircraft completes 15,000 pressurisation cycles (roughly, takeoffs and landings where the cabin is pressurised).\n\n**Why it matters:** During fatigue testing, engineers found cracks developing in the aircraft skin near this door hinge. Without this fix, the skin could fail prematurely from metal fatigue — potentially compromising the aircraft's structural integrity. The reinforcement plate extends the safe life of this critical area.\n\n**Who needs to act:** Anyone operating the affected Fokker F50 serial numbers must ensure this modification is completed within the specified timeframe."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f50-45-fuselage-power-supply-box-surround-structure","history":"/api/acts/ad-f50-45-fuselage-power-supply-box-surround-structure/history","analysis":"/api/acts/ad-f50-45-fuselage-power-supply-box-surround-structure/analysis","conflicts":"/api/acts/ad-f50-45-fuselage-power-supply-box-surround-structure/conflicts","importantCases":"/api/acts/ad-f50-45-fuselage-power-supply-box-surround-structure/important-cases","documents":"/api/acts/ad-f50-45-fuselage-power-supply-box-surround-structure/documents"}}