{"id":"F2006B09869","name":"AD/F50/42 Amdt 1 - External Power Connection Relay Fitment","slug":"ad-f50-42-amdt-1-external-power-connection-relay-fitment","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54977,"registerId":"commonwealth-F2006B09869-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F50/42 Amdt 1 - External Power Connection Relay Fitment","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/F50/42\n\nAmdt 1\n\n\nExternal Power Connection Relay Fitment 5/91\n\n \n\nApplicability: All F 27 MK50 aircraft as listed in the requirement document.\n\n \n\nRequirement: Action in accordance with the technical requirements of RLD Airworthiness Directive 90-137 dated 14 December 1990.\n\n \n\nNote: Fokker SB F50-24-015 dated 29 November 1990 also refers.\n\n \n\nCompliance: As specified in the requirement document.\n\n \n\nBackground: Reports indicate that the potential exists for serious damage to occur to contactors and circuit breakers during ground power to aircraft power change-over.\n\n \n\nNote: Amendment 1 to this AD is issued to clarify the compliance statement.\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":"Amendment 1 states it was issued to clarify the compliance statement (Note). The AD continues to apply to the same set of F27 Mk50 aircraft and continues to require the actions set out in RLD Airworthiness Directive 90-137 (Applicability; Requirement). The text of this AD does not expand the applicability or add new technical requirements; it primarily clarifies how compliance should be read."},"complexity_factors":["Directive is short and limited in scope (single aircraft type group) (Applicability).","Technical requirements are contained in an external document (RLD AD 90-137), creating a cross-reference dependency (Requirement).","Compliance timing and tasks are not repeated in this text but are delegated to the requirement document, requiring operators to obtain and interpret that document (Compliance).","Implementation requires specialised maintenance skills, parts procurement and aircraft downtime, adding operational complexity despite simple regulatory wording (Requirement; Compliance).","Amendment clarifies compliance wording rather than adding new obligations, reducing legal interpretive complexity but requiring attention to the updated language (Note)."],"plain_english_summary":"The directive requires owners/operators of Fokker F50 (F27 Mk50) aeroplanes to fit an external power-connection relay, following the technical instructions in RLD Airworthiness Directive 90‑137, to prevent contactor and circuit‑breaker damage when switching from ground to aircraft power. The Civil Aviation Safety Authority mandates compliance by reference; operators bear the parts, labour and downtime costs and must obtain and follow the referenced RLD AD and Fokker service bulletin to meet the requirement."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard airworthiness directive with narrow, specific scope (single aircraft type, single safety issue). Amendment 1 merely clarifies compliance timing; it does not expand the scope beyond the original electrical safety issue."},"complexity_factors":["Very short document (under 300 words)","Only 1 substantive requirement (relay fitment)","Single cross-reference to external technical document (RLD AD 90-137)","No defined terms section","No conditional logic or nested exceptions","Straightforward applicability (all F27 Mk 50 aircraft in listed document)","Amendment is purely clarifying — no additional substantive requirements"],"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 aircraft.\n\n**What it does:** It requires owners and operators of Fokker F50 aircraft (also known as F27 Mk 50) to install a specific relay (an electrical switch) in the external power connection system. This relay prevents damage to electrical contactors and circuit breakers when switching between ground power and the aircraft's own power.\n\n**Why it matters:** Without this fix, there's a risk of \"serious damage\" to critical electrical components during power change-over. This could lead to electrical failures, potentially affecting flight safety.\n\n**Who must comply:** Anyone operating Fokker F50 series aircraft listed in the referenced technical document (RLD Airworthiness Directive 90-137).\n\n**What action is required:** Aircraft must be modified according to the technical specifications in the Dutch aviation authority's directive (RLD AD 90-137) from December 1990. Operators should also check Fokker Service Bulletin F50-24-015 for guidance.\n\n**Key point:** Amendment 1 simply clarifies when and how operators must comply — it doesn't change the actual safety fix required."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f50-42-amdt-1-external-power-connection-relay-fitment","history":"/api/acts/ad-f50-42-amdt-1-external-power-connection-relay-fitment/history","analysis":"/api/acts/ad-f50-42-amdt-1-external-power-connection-relay-fitment/analysis","conflicts":"/api/acts/ad-f50-42-amdt-1-external-power-connection-relay-fitment/conflicts","importantCases":"/api/acts/ad-f50-42-amdt-1-external-power-connection-relay-fitment/important-cases","documents":"/api/acts/ad-f50-42-amdt-1-external-power-connection-relay-fitment/documents"}}