{"id":"F2006B11261","name":"AD/M601/1 - Fuel Control Unit","slug":"ad-m601-1-fuel-control-unit","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":57044,"registerId":"commonwealth-F2006B11261-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.002.png)\n\n![](image.002.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.","sortOrder":0},{"sectionNumber":"AD/M601/1 Fuel Control Unit 10/2001 DM","sectionType":"part","heading":"AD/M601/1 Fuel Control Unit 10/2001 DM","content":"# ![](image.003.png)AD/M601/1 Fuel Control Unit 10/2001 DM\n\nApplicability: M601 series engines detailed in Walter Mandatory Bulletin Number: A M6O1D/29a, A M601D-1/3a, A M601D-11NZ/3a, A M601E/23a, A M601E-11/4a, A M601E- 21/2a, A M601F/3a, A M601T/7a, A M601Z/15a.\n\nRequirement: Replace the fuel control unit relief valve in accordance with the accomplishment instructions detailed in the Mandatory Bulletin Number: A M6O1D/29a, A M601D- 1/3a, A M601D-11NZ/3a, A M601E/23a, A M601E-11/4a, A M601E-21/2a, A M601F/3a, A M601T/7a, A M601Z/15a.\n\nNote: Czech Republic Airworthiness Directive T-095/2000 refers.\n\nCompliance: 1. Single engine aircraft; prior to further flight, effective 22 August 2001.\n\n    2. Multi engine aircraft; no later than 31 October 2001.\n\n    3. Spare fuel control units; prior to installation in an aircraft.\n\nThis Airworthiness Directive becomes effective on 22 August 2001.\n\nBackground: This Directive has been issued to require the replacement of the FCU relief valve. The requirement is in response to reports of fuel leaks from the FCU servomotor relief valve. The fuel leaks result from failure of the relief valve seals.\n\n![Signature of Eugene Paul Holzapfel Delegate of the Civil Aviation Safety Authority](image.004.png)  \n\nEugene Paul Holzapfel\n\nDelegate of the Civil Aviation Safety Authority 13 August 2001\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 22 August 2001.","sortOrder":1}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard airworthiness directive with a narrow, specific safety purpose: addressing a known mechanical defect in a particular engine series. The scope remains tightly focused on the fuel control unit relief valve replacement and has not expanded beyond this original safety intent."},"complexity_factors":["Single operational requirement (replace one specific component)","Minimal conditional logic (only three compliance categories: single-engine, multi-engine, and spare parts)","No defined terms section - uses plain technical language","Short document (approximately 250 words excluding headers)","No cross-references to other legislation (only references manufacturer's bulletins and one related foreign directive as context)","Clear, linear structure: Applicability → Requirement → Compliance → Background"],"plain_english_summary":"This safety order requires owners/operators of aircraft with Walter M601 series engines to replace a faulty fuel control unit relief valve whose seals can leak. Single‑engine aircraft must comply before next flight (from 22 Aug 2001); multi‑engine aircraft by 31 Oct 2001; spare units must be corrected before installation. It prevents fuel leaks that can cause fires or engine failure."},"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"},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"No change evident from the text: the AD applies to the listed Walter M601-series engines and requires replacement of the FCU relief valve for in-service aircraft and spare units with specified compliance dates, matching the safety response set out in the Background, Applicability, Requirement and Compliance sections."},"complexity_factors":["Narrow technical remedy confined to replacement of a single component reduces legal complexity (see Requirement).","Multiple M601 engine variants listed increases identification work for operators (see Applicability).","Staggered compliance deadlines for single‑engine, multi‑engine and spares create scheduling and operational coordination (see Compliance).","Procedural steps depend on an external Mandatory Bulletin for accomplishment instructions, requiring cross-reference (see Requirement).","Reference to a foreign AD (Czech T-095/2000) adds an international-documentation linkage (see Note).","Issued under CAR 1998 subregulation 39.1(1) — regulatory discretion concentrated in CASA delegate (see heading/signature)."],"plain_english_summary":"Mandates replacement of the fuel control unit (FCU) relief valve on specified Walter M601-series engines, carried out in accordance with the referenced Mandatory Bulletin. The stated cause is reports of fuel leaks from failed relief-valve seals.\n\nOwners/operators and those fitting spare units must replace affected valves by the AD’s deadlines: single-engine aircraft before next flight, multi-engine by 31 October 2001, and spares before installation. The AD was issued by the CASA delegate under CAR 1998 subregulation 39.1(1)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-m601-1-fuel-control-unit","history":"/api/acts/ad-m601-1-fuel-control-unit/history","analysis":"/api/acts/ad-m601-1-fuel-control-unit/analysis","conflicts":"/api/acts/ad-m601-1-fuel-control-unit/conflicts","importantCases":"/api/acts/ad-m601-1-fuel-control-unit/important-cases","documents":"/api/acts/ad-m601-1-fuel-control-unit/documents"}}