{"id":"F2006B05167","name":"AD/CESSNA 188/31 Amdt 1 - Vented Fuel Caps","slug":"ad-cessna-188-31-amdt-1-vented-fuel-caps","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":45291,"registerId":"commonwealth-F2006B05167-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 188/31 Amdt 1 - Vented Fuel Caps","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nCessna 188 (Agwagon) Series Aeroplanes\n\nAD/CESSNA 188/31\n\nAmdt 1\n\n  \nVented Fuel Caps 8/80\n\nApplicability: Models 188 and A188 (with wing fuel tanks) with S/Nos. 653, 18800446 to 18800572 and 18800573 to 18800762.\n\nRequirement: Install vented fuel cap(s) in accordance with Cessna SL No. SE77-6;\n\nNote: FAA AD 79-10-14, Amendment 39-3475 refers.\n\nNote: Installation of a placard is not an acceptable alternative to installation of vented fuel caps.\n\nCompliance: Within 100 hours time in service after 31 August 1979 or before 1 January 1980 whichever is the later.\n\nBackground: To guard against the possibility of either an obstructed primary vent or sticking of the fuel tank vent valve it has been found necessary to provide secondary venting in the form of vented fuel caps. Due to some misinterpretation of this Directive a NOTE has now been added to disallow the fitting of a placard.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The amendment narrows acceptable compliance options by adding an explicit Note that disallows fitting a placard as an alternative to installing vented fuel caps. The underlying Requirement — installation of vented fuel caps per Cessna SL No. SE77-6 for the listed serial numbers within the stated timeframe — remains, but the added Note removes the previously misinterpreted alternative and therefore reduces the set of actions that satisfy the Directive. (Requirement; Note; Background)"},"complexity_factors":["Specific serial-number filtering of applicability (models 188 and A188 with specified S/N ranges)","Mandatory physical modification that references an external document (Cessna SL No. SE77-6) rather than containing full technical detail","Fixed compliance window tied to service hours and calendar dates","Explicit prohibition of an alternative compliance method (placard), which removes flexibility","Cross-reference to an external FAA AD for related context"],"plain_english_summary":"What this instrument does\n\n- This Airworthiness Directive (AD) requires owners/operators of certain Cessna 188 and A188 aeroplanes (wing fuel tank versions, specific serial number ranges listed) to install vented fuel caps. (Applicability; Requirement)\n- The installation must follow the instructions in Cessna Service Letter No. SE77-6. (Requirement)\n- Fitting a placard instead of installing vented caps is explicitly not acceptable. (Note)\n- The work must be completed within 100 hours time in service after 31 August 1979 or before 1 January 1980, whichever is later. (Compliance)\n\nWhy the change was made (official rationale)\n\n- The AD states the purpose is to provide secondary venting via vented fuel caps to reduce the risk that an obstructed primary vent or a sticking fuel tank vent valve will prevent proper venting of the wing tanks. (Background)\n- The Background also explains that a NOTE was added because some people misinterpreted the Directive and thought a placard could be used as an alternative. That misunderstanding prompted the explicit prohibition of a placard. (Background; Note)\n\nWho is affected and who pays\n\n- Aircraft owners/operators of the listed Cessna 188/A188 serial numbers must have the vented fuel caps installed and therefore will bear the direct cost of obtaining parts and paying for installation or maintenance labour. (Applicability; Requirement)\n- Maintenance organisations or technicians authorised to carry out Cessna Service Letter work will perform the installations and receive the related business. (Requirement)\n\nMechanical effect and implementation\n\n- The mechanical effect is a change to the aircraft: removal/alteration or addition of fuel caps so that wing tank fuel caps provide secondary venting as specified in Cessna SL No. SE77-6. (Requirement)\n- Compliance is time-limited: installations must be completed within the specified service hours/date window. (Compliance)\n- The AD cross-references FAA AD 79-10-14 (Amendment 39-3475) but requires compliance with the Cessna Service Letter named in this AD. (Note)\n\nCosts, incentives, trade-offs and risks (source-grounded observations)\n\n- Cost and compliance burden: Owners/operators pay for parts and labour to meet the Requirement within the stated compliance window. (Requirement; Compliance)\n- Flexibility loss: The AD removes one informal alternative (placing a placard) by stating that a placard is not acceptable, reducing choice in how to demonstrate compliance. (Note)\n- Incentives for service providers: The Requirement channels maintenance work toward providers able to perform the service letter procedure, creating demand for that work. (Requirement)\n- Implementation risk and ambiguity: A prior misinterpretation of the Directive (some thought a placard acceptable) prompted the added Note; that history indicates a risk that the AD could be misunderstood without the explicit prohibition. (Background; Note)\n- Administrative discretion: The AD is a binding regulatory requirement issued by the Civil Aviation safety authority under the Part 39 schedule; the text prescribes the method (follow Cessna SL No. SE77-6) rather than leaving method to individual operators. (Requirement)\n\nNet procedural effect\n\n- Operators of the listed aircraft must follow a specified service instruction within a fixed timeframe and cannot rely on a placard as an administrative workaround. (Applicability; Requirement; Compliance; Note)\n\nSource references: Applicability; Requirement; Note; Compliance; Background."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a targeted safety directive for a specific aircraft type. The amendment merely clarifies compliance requirements (rejecting placards as an alternative) without expanding the scope beyond the original safety purpose of preventing fuel system venting failures."},"complexity_factors":["Very short document (under 300 words)","Only 4 defined elements: applicability (specific models/serial numbers), requirement (single action), compliance deadline, and background","No cross-references to other legislation sections — only references to external Cessna service letter and FAA directive for context","Simple conditional logic: one deadline calculation ('whichever is the later')","Single amendment adding one clarifying note about placards not being acceptable"],"plain_english_summary":"This is an **Airworthiness Directive** — essentially a mandatory safety order for aircraft owners and operators. It applies to specific **Cessna 188 Agwagon agricultural aircraft** (crop dusters) built with certain serial numbers.\n\n**What it requires:**\n- Owners must replace standard fuel caps with **vented fuel caps** on these planes\n- This must be done following Cessna's Service Letter SE77-6\n- The work must be completed within 100 flight hours after 31 August 1979, or before 1 January 1980 — whichever gives more time\n\n**Why it matters:**\n- The original fuel system had a design flaw: if the main vent got blocked or the vent valve stuck, pressure could build up in the tank\n- This could cause fuel flow problems or even tank damage — dangerous when you're flying low over crops\n- The \"Amendment 1\" (update) clarifies that simply putting a warning sticker (placard) on the plane is **not good enough** — the physical vented caps must be installed\n\n**Who needs to act:**\n- Anyone operating the affected Cessna 188 models with wing fuel tanks and serial numbers in the listed ranges\n- Maintenance organisations servicing these aircraft"}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-188-31-amdt-1-vented-fuel-caps","history":"/api/acts/ad-cessna-188-31-amdt-1-vented-fuel-caps/history","analysis":"/api/acts/ad-cessna-188-31-amdt-1-vented-fuel-caps/analysis","conflicts":"/api/acts/ad-cessna-188-31-amdt-1-vented-fuel-caps/conflicts","importantCases":"/api/acts/ad-cessna-188-31-amdt-1-vented-fuel-caps/important-cases","documents":"/api/acts/ad-cessna-188-31-amdt-1-vented-fuel-caps/documents"}}