{"id":"F2005L02079","name":"AD/B747/331 - Frequency Converters","slug":"ad-b747-331-frequency-converters","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":36286,"registerId":"commonwealth-F2005L02079-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 747 Series Aeroplanes","sectionType":"division","heading":"Boeing 747 Series Aeroplanes","content":"### Boeing 747 Series Aeroplanes\n\n| AD/B747/331 | Frequency Converters | 9/2005 |\n| ----------- | -------------------- | ------ |\n\n| Applicability: | Model 747-200F and -400 series aeroplanes as listed in Boeing Service Bulletin (SB) 747-25-3313, Revision 1, dated 15 May 2003.                                                                                                                                                                                                                                                                                                                                |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Replace the frequency converter(s) used to supply electrical power to utility outlets (for the galley, medical equipment or personal computers) with modified frequency converter(s) in accordance with the Accomplishment Instructions of SB 747-25-3313, Revision 1.                                                                                                                                                                                         |\n|                | Note 1: SB 747-25-3313, Revision 1, refers to JAMCO Service Bulletin CAW74-25-1697, dated 7 June 2002, as an additional source of information for procedures to remove and install certain galley frequency converters.                                                                                                                                                                                                                                        |\n|                | Later revisions of the above Boeing SB, approved by the United States Federal Aviation Administration (FAA) as an Alternate Method of Compliance (AMOC) to FAA AD 2005-12-10, are considered acceptable for compliance with the equivalent Requirements of this Directive.                                                                                                                                                                                     |\n|                | Note 2: FAA AD 2005-12-10 Amdt 39-14126 refers.                                                                                                                                                                                                                                                                                                                                                                                                                |\n| Compliance:    | Within 18 months after the effective date of this Directive.                                                                                                                                                                                                                                                                                                                                                                                                   |\n|                | This Airworthiness Directive becomes effective on 1 September 2005.                                                                                                                                                                                                                                                                                                                                                                                            |\n| Background:    | The FAA has received a report that a hard short condition between the frequency converter's output and its downstream circuit breakers will produce a continuous current that could cause the undersized output wiring to overheat. This Directive requires the replacement of the frequency converter(s) used to supply electrical power for utility outlets (for the galley, medical equipment, or personal computers) with modified frequency converter(s). |\n\n|     | This Directive is issued to prevent the overheating of the frequency converter's undersized output wiring, which could lead to the failure of a wire bundle and consequent adverse effects on other systems sharing the affected wire bundle. |\n| --- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n21 July 2005","sortOrder":0},{"sectionNumber":"AD/B747/331","sectionType":"part","heading":"AD/B747/331","content":"## AD/B747/331","sortOrder":1},{"sectionNumber":"Frequency Converters","sectionType":"part","heading":"Frequency Converters","content":"## Frequency Converters","sortOrder":2},{"sectionNumber":"9/2005","sectionType":"part","heading":"9/2005","content":"## 9/2005","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The Directive implements the stated original safety purpose: replacing affected frequency converters on listed 747 models to prevent wiring overheating. It aligns with FAA AD 2005-12-10 and confines action to aircraft identified in Boeing SB 747-25-3313 Revision 1; later FAA‑approved SB revisions are acceptable as alternate compliance, but the Directive does not broaden or narrow the stated safety scope beyond that."},"complexity_factors":["Technical parts replacement requiring removal and installation of frequency converters (Requirement)","Reliance on manufacturer service bulletin as the compliance procedure (Requirement; Note 1)","Cross‑reference to and acceptance of FAA‑approved later revisions as Alternate Methods of Compliance (Note 1; Note 2)","Fixed compliance deadline (18 months) that obliges operators to schedule maintenance and bear costs (Compliance)","Limited applicability to specific models listed in the Boeing SB, narrowing affected population but concentrating cost on those operators (Applicability)","Safety risk identification based on an FAA report about wiring overheating and potential wire‑bundle failure (Background)"],"plain_english_summary":"This Directive requires operators of Boeing 747-200F and -400 series listed in Boeing Service Bulletin 747-25-3313, Revision 1 to replace the frequency converters that supply galley, medical and personal-computer utility outlets with modified units, using the Boeing SB (later FAA‑approved revisions permitted). (Applicability; Requirement; Note on AMOC)\n\nAircraft owners/operators must pay for and complete the replacements within 18 months of the Directive’s effective date (1 September 2005) to address a reported risk of output‑wiring overheating and possible wire‑bundle failure. (Compliance; Background)"},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrow Airworthiness Directive addressing a specific safety defect in defined aircraft models. The scope remains tightly focused on the identified wiring overheating risk and the required frequency converter replacement."},"complexity_factors":["Single, specific technical requirement (replace defined component)","Only 2 defined document references (Boeing SB 747-25-3313 and JAMCO SB CAW74-25-1697)","Clear applicability limited to specific aircraft models (747-200F and -400 series)","Simple compliance deadline (18 months from effective date)","No nested exceptions or conditional logic — straightforward mandate","Short document (approximately 300 words of substantive content)"],"plain_english_summary":"This CASA Airworthiness Directive mandates replacement of specific frequency converters on affected Boeing 747‑200F and 747‑400 aircraft (per Boeing Service Bulletin 747‑25‑3313) because a design flaw can let wiring overheat during a short circuit, risking system damage and fire. Operators named in the service bulletin must fit the modified converters within 18 months of 1 September 2005 to mitigate the hazard."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-331-frequency-converters","history":"/api/acts/ad-b747-331-frequency-converters/history","analysis":"/api/acts/ad-b747-331-frequency-converters/analysis","conflicts":"/api/acts/ad-b747-331-frequency-converters/conflicts","importantCases":"/api/acts/ad-b747-331-frequency-converters/important-cases","documents":"/api/acts/ad-b747-331-frequency-converters/documents"}}