{"id":"F2005L00100","name":"AD/SF340/97 - DC Generating System - Undervoltage Protection","slug":"ad-sf340-97-dc-generating-system-undervoltage-protection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":33490,"registerId":"commonwealth-F2005L00100-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"SAAB SF340 Series Aeroplanes","sectionType":"division","heading":"SAAB SF340 Series Aeroplanes","content":"### SAAB SF340 Series Aeroplanes\n\n| AD/SF340/97 | DC Generating System - Undervoltage Protection | 2/2005 |\n| ----------- | ---------------------------------------------- | ------ |\n\n| Applicability: | SAAB SF340A Serial No. 004 to 159 inclusive, SAAB 340B Serial No. 160 to 367 inclusive.                                                                                                                                                                                                                                                                                                                                                                                                                           |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Install a Generator Control Unit (GCU) model 51539-007B in accordance with SAAB AB Service Bulletin 340-24-026 Rev 2 dated 29 October 2004 or later revision.                                                                                                                                                                                                                                                                                                                                                     |\n|                | Note 1: Installation of GCU model 51539-007B terminates the repetitive brush inspection required by AD/SF340/96.                                                                                                                                                                                                                                                                                                                                                                                                  |\n|                | Note 2: LFV AD No 1-197 (EASA Approval 2004-10860) refers.                                                                                                                                                                                                                                                                                                                                                                                                                                                        |\n| Compliance:    | No later than three years after the effective date of this Directive.                                                                                                                                                                                                                                                                                                                                                                                                                                             |\n|                | This Airworthiness Directive becomes effective on 17 February 2005.                                                                                                                                                                                                                                                                                                                                                                                                                                               |\n| Background:    | A premature failure of the generator can cause a low voltage situation in flight, if the aircraft is not equipped with the GCU 51539-007B. This GCU was included in the type design from serial number 368 and has been available as an option for earlier manufactured aeroplanes. Service experience has shown that installation of the new GCU is needed in order to meet the requirements of continued airworthiness in accordance with EC regulation 1702/2003 Part 21A.3B and associated guidance material. |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n13 December 2004\n\nThe above AD is notified in the Commonwealth of Australia Gazette on 26 January 2005.","sortOrder":0},{"sectionNumber":"AD/SF340/97","sectionType":"part","heading":"AD/SF340/97","content":"## AD/SF340/97","sortOrder":1},{"sectionNumber":"DC Generating System - Undervoltage Prot","sectionType":"part","heading":"DC Generating System - Undervoltage Protection","content":"## DC Generating System - Undervoltage Protection","sortOrder":2},{"sectionNumber":"2/2005","sectionType":"part","heading":"2/2005","content":"## 2/2005","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This Directive stays within the original safety purpose: eliminate in-flight low-voltage risk from premature generator failures by retrofitting a specific GCU to earlier-production aircraft. It does replace (terminate) a prior recurring-inspection requirement with a one-off retrofit, but that substitution is consistent with the Directive's stated aim and does not materially broaden the applicability, affected parties, or required interventions beyond the original safety objective."},"complexity_factors":["Single, discrete required action: install GCU model 51539-007B (straightforward technical remedy).","Applicability defined by two serial-number ranges (SF340A 004–159, SF340B 160–367) – limited scope.","Compliance deadline is a single time condition (three years) with an explicit effective date.","References a single manufacturer service bulletin (SAAB AB Service Bulletin 340-24-026 Rev 2 or later) — dependency on external document.","Terminates a prior AD's repetitive inspection requirement (cross-reference to AD/SF340/96) — one cross-reference.","References an external regulatory standard and an LFV/EASA approval (EC Regulation 1702/2003 Part 21A.3B; LFV AD No 1-197) — some regulatory cross-linking.","Few conditional rules or nested exceptions — no multiple alternative compliance pathways set out in the Directive itself.","Short text length and limited number of operative paragraphs reduces cross-referencing complexity."],"plain_english_summary":"Requires operators of SAAB SF340A (s/n 004–159) and SF340B (s/n 160–367) to install Generator Control Unit 51539-007B per SAAB Service Bulletin 340-24-026 (or later) within three years. The retrofit terminates prior repetitive generator-brush inspections, aims to reduce in-flight low DC-voltage risk, and shifts one-off parts, labour and downtime costs to aircraft owners/operators while creating demand for approved suppliers and fitment services."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — a targeted safety modification for specific aircraft serial numbers. It does not expand beyond its initial purpose of addressing the undervoltage protection issue."},"complexity_factors":["Single, specific technical requirement (install one specific part model)","Narrow applicability limited to specific aircraft serial number ranges","Simple compliance deadline (fixed 3-year window from effective date)","Minimal cross-referencing (only refers to one Service Bulletin and one superseded AD)","No conditional logic, exceptions, or alternative compliance methods","Short document (approximately 200 words of substantive content)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's aviation regulator (CASA) requiring specific repairs or modifications to aircraft.\n\n**What it does:**\nOrders owners and operators of certain **SAAB SF340 aircraft** (a regional turboprop airliner) to install an upgraded **Generator Control Unit (GCU)** — specifically model 51539-007B. This device protects against electrical system failures caused by low voltage.\n\n**Who it affects:**\n- SAAB SF340A aircraft with serial numbers 004–159\n- SAAB 340B aircraft with serial numbers 160–367\n\n**Why it matters:**\nWithout this upgrade, a generator failure in flight could cause dangerous low voltage conditions. The new GCU was already standard on newer aircraft (from serial 368 onwards), but older planes need retrofitting. Once installed, operators no longer need to perform repetitive brush inspections previously required under an earlier safety order (AD/SF340/96).\n\n**Deadline:**\nAircraft must be modified within **3 years** of 17 February 2005 (so by February 2008)."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-sf340-97-dc-generating-system-undervoltage-protection","history":"/api/acts/ad-sf340-97-dc-generating-system-undervoltage-protection/history","analysis":"/api/acts/ad-sf340-97-dc-generating-system-undervoltage-protection/analysis","conflicts":"/api/acts/ad-sf340-97-dc-generating-system-undervoltage-protection/conflicts","importantCases":"/api/acts/ad-sf340-97-dc-generating-system-undervoltage-protection/important-cases","documents":"/api/acts/ad-sf340-97-dc-generating-system-undervoltage-protection/documents"}}