{"id":"F2006B09915","name":"AD/F50/84 Amdt 1 - Fuel - Ventilation float valve & sniffle valve","slug":"ad-f50-84-amdt-1-fuel-ventilation-float-valve-sniffle-valve","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":55121,"registerId":"commonwealth-F2006B09915-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F50/84 Amdt 1 - Fuel - Ventilation float valve & sniffle valve","content":"![](image.001.png)\n\n![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\nOn the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/F50/84 and issues the following AD under subregulation 39.1 (1) of CASR 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.\n\n![](image.001.png)\n\nFokker F50 (F27 Mk 50) Series Aeroplanes\n\nAD/F50/84\n\nAmdt 1\n\n  \nFuel - Ventilation Float Valve & Sniffle Valve 13/2004\n\nApplicability: Model F.27 Mk.050, 0502 and 0604 aeroplanes with serial numbers 20103 to 20204 and 20206 to 20212.\n\nRequirement: 1. Replace Ventilation Float Valves Part Number (P/N) 29000 and P/N 29000-1 with improved units P/N 29000-3 in accordance with Part 2 of Accomplishment Instructions of Fokker Services Service Bulletin (SB) F50-28-020 dated 15 April 2003 or SB F50-28-022 dated 23 August 2004 as is applicable.\n\n    2. Replace Sniffle Valves P/N 2770002-101 with P/N 2770002-103 in accordance with Part 2 of Accomplishment Instructions of Fokker Services SB F50-28-021.\n\n    3. No Ventilation Float Valves P/N 29000 or P/N 29000-1 or Sniffle Valves P/N 2770002-101 may be installed on any aircraft.\n\nLater CAA NL approved revisions of the referenced service bulletins may be used in lieu of those detailed in the requirements section of this Directive.\n\nNote: CAA NL AD 2003-090/2 and EASA Approval No 2004-10037 dated 30 September 2004 refers.\n\nCompliance: For Requirement 1:\n\nFor P/N 29000 valves, remains unchanged as within 24 months after 17 September 2003.\n\nFor P/N 29000-1 valves, within 10 calender months from the effective date of this Directive.\n\nFor Requirement 2: Remains unchanged as; Within 10 months after 17 September 2003.\n\nFor Requirement 3: After the effective date of this Directive. This Amendment becomes effective on 23 December 2004.\n\nFokker F50 (F27 Mk 50) Series Aeroplanes\n\nAD/F50/84 Amdt 1 (continued)\n\nBackground: Operators have reported four occurrences of fuel collector tank implosion caused by insufficient ventilation of the fuel tanks. It is thought that freezing (or failure) of both the ventilation float and sniffle valves are the reason for reduced ventilation. The intent of this Directive is to correct an unsafe condition by replacing both valves with those of an improved design.\n\nFurther testing has identified another ventilation float valve that has similar problems to those valve detailed in the original issue of this Directive.\n\nThe original issue of this Directive became effective on 15 September 2003.\n\n![](image.002.png)  \n\nJames Coyne\n\nDelegate of the Civil Aviation Safety Authority 9 November 2004\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 1 December 2004.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"This amendment revokes and replaces the original AD and broadens/clarifies the remedial scope: it adds an additional affected ventilation float valve P/N (29000-1) with a shorter compliance deadline, retains the original P/N 29000 deadline, specifies replacement of sniffle valves, and imposes a prohibition on reinstalling the older P/Ns. It also formally permits use of later CAA NL‑approved revisions of the referenced Service Bulletins (see Requirement 1–3, Compliance, Note, Background)."},"complexity_factors":["Targeted applicability by aircraft serial number (Applicability) — narrows affected fleet but requires operators to check serial lists.","Multiple part-number actions: replace P/N 29000 and 29000-1 with P/N 29000-3; replace sniffle P/N 2770002-101 with P/N 2770002-103; and prohibition on installing old P/Ns (Requirement 1–3).","Different compliance timeframes for different part numbers (Compliance) — P/N 29000: within 24 months from 17 Sep 2003; P/N 29000-1: within 10 calendar months from this Directive's effective date; sniffle valves: within 10 months after 17 Sep 2003.","Dependency on external technical instructions and approvals: actions must follow Fokker Services Service Bulletins, with later CAA NL approved revisions permitted; cross‑references to CAA NL and EASA approvals (Requirement; Note).","Regulatory history and amendment: this document revokes and replaces an earlier AD and adds parts/testing findings from further investigation (opening paragraphs; Background), so operators must track version history.","Operational implication: ban on installing old valves after the effective date creates an ongoing parts‑control/compliance obligation (Requirement 3; Compliance)."],"plain_english_summary":"This Airworthiness Directive requires operators of certain Fokker F50 (F27 Mk 50) aeroplanes (serial numbers 20103–20204 and 20206–20212) to replace specified fuel ventilation float valves and sniffle valves with improved part numbers and forbids reinstalling the old parts. It responds to reported fuel-collector tank implosions thought caused by valve freezing or failure. Operators must follow Fokker Service Bulletins and meet part-specific replacement deadlines; later regulator‑approved SB revisions may be used."},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":true,"description":"This is Amendment 1 to an existing directive (AD/F50/84). The original directive only addressed ventilation float valves P/N 29000. This amendment expands the scope to also cover P/N 29000-1 valves (which were found to have similar problems during further testing) and adds Requirement 3 prohibiting installation of the old parts. The compliance deadlines have also been modified with a new 10-month window for the additional valve type."},"complexity_factors":["Multiple part numbers and cross-references to manufacturer service bulletins (SB F50-28-020, SB F50-28-021, SB F50-28-022)","Tiered compliance deadlines based on specific part numbers installed (P/N 29000 vs P/N 29000-1)","Reference to foreign aviation authority approvals (CAA NL AD 2003-090/2, EASA Approval No 2004-10037)","Conditional language allowing later approved revisions of service bulletins to be used","Specific serial number ranges limiting applicability"],"plain_english_summary":"This AD mandates replacement of faulty fuel ventilation and sniffle valves on certain Fokker F50 aircraft (specific serial ranges covering F.27 Mk.050/0502/0604) because freezing/failure has caused four fuel-tank implosions. Operators must fit improved valve parts and the old part numbers are barred from future installation. Compliance deadlines vary (10–24 months); the directive takes effect 23 December 2004 to prevent further structural damage and safety risk."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f50-84-amdt-1-fuel-ventilation-float-valve-sniffle-valve","history":"/api/acts/ad-f50-84-amdt-1-fuel-ventilation-float-valve-sniffle-valve/history","analysis":"/api/acts/ad-f50-84-amdt-1-fuel-ventilation-float-valve-sniffle-valve/analysis","conflicts":"/api/acts/ad-f50-84-amdt-1-fuel-ventilation-float-valve-sniffle-valve/conflicts","importantCases":"/api/acts/ad-f50-84-amdt-1-fuel-ventilation-float-valve-sniffle-valve/important-cases","documents":"/api/acts/ad-f50-84-amdt-1-fuel-ventilation-float-valve-sniffle-valve/documents"}}